Добірка наукової літератури з теми "Excess factor"

The researcher intends to test the four carhart factor model of stock excess return in companies incorporated in Kompas 100 for the 2014-2016 period. Regression analysis was performed on four carhart factor models, namely market returns, firm size, book to market, and momentum towards excess return. The results of this study indicate that in the partial hypothesis testing market return, firm size, and book to market equty variables significantly influence the excess return, while the momentum variable does not significantly influence the magnitude of excess return.Keywords: Four factors, market returns, firm size, book to market equity, momentum, excess stock returns

This paper proposes a multilayer network risk factor pricing model to depict the impact of interactions between stocks on excess stock returns by constructing the network risk factor based on the stock multilayer network and introducing it to the traditional three-factor pricing model. According to China’s stock market data, we find that compared with the traditional three-factor model, the multilayer network risk factor pricing model can achieve higher fitting degree. Meanwhile, the multilayer network risk factor has a significant positive impact on the excess stock returns in most cases.

Empirical models of the supply of criminal offenses in the United States have shown a positive relationship between the proportion of the population that is non-white (RACE) and crime rates. Though non-whites in the United States possess more “criminal capital” than the average person, such studies do not take into consideration this excess criminal capital. Since RACE and the omitted excess criminal capital are correlated, it will pick up the influence of the excess criminal capital. Using cross-sectional data from Florida's municipalities, we show that after adjusting for excess criminal capital, RACE has no significant relationship with crime.

This study investigated the application of Machine Learning to portfolio selection by comparing the application of a Factor Based Investment strategy to one using a Support Vector Machine performing a classification task. The Factor Based Strategy uses regression in order to identify factors correlated to returns, by regressing excess returns against the factor values using historical data from the JSE. A portfolio-sort method is used to construct portfolios. The machine learning model was trained on historical share data from the Johannesburg Stock Exchange. The model was tasked with classifying whether a share over or under performed relative to the market. Shares were ranked according to probability of over-performance and divided into equally weighted quartiles. The excess return of the top and bottom quartiles was used to calculate portfolio payoff, which is the basis for comparison. The experiments were divided into time periods to assess the consistency of the factors over different market conditions. The time periods were defined as pre-financial crisis, during the financial crisis, post financial crisis and over the full period. The study was conducted in the context of the Johannesburg Stock Exchange. Historical data was collected for a 15-year period - from May 2003 to May 2018 - on the constituents of the All Share Index (ALSI). A rolling window methodology was used where the training and testing window was shifted with each iteration over the data. This allowed for a larger number of predictions to be made and for a greater period of comparison with the factorbased strategy. Fourteen factors were used individually as the basis for portfolio construction. While combinations of factors into Quality, Value and Liquidity and Leverage categories was used to investigate the effect of additional inputs into the model. Furthermore, experiments using all factors together were performed. It was found that a single factor FBI can consistently outperform the market, a multi factor FBI also provided consistent excess returns, but the SVM provided consistently larger excess returns with a wide range of factor inputs and beat the FBI in 12 of the 14 different experiments over different time periods.

This essay will compare the capital asset pricing model (CAPM), Fama and French threefactor model and Carhart´s four-factor model, to see which of these models that can explain portfolio excess returns best on the Swedish stock market. This thesis will tempt to validate the three and four-factor models because of the limited amount of research done on the Swedish stock market. The results indicate that the three-factor model improves explanatory power for portfolio returns in comparison to the CAPM, and the four-factor model gives a small improvement in the explanatory power compared to the three-factor model. The results also indicate that all models have a low explanatory power when the market is volatile.

During the last decade, investments into the Swedish mutual fund market have increased substantially. The increased popularity of actively managed Swedish equity funds among households and investment companies, correspondingly, funds need to deliver substantial results, raised the importance to evaluate these funds’ performance. This thesis adds to the scarce empirical literature on Swedish equity mutual fund performance. Employing the Fama-French three factor model, it analyzes whether actively managed Swedish equity mu- tual funds outperform the Fama-French benchmarks net- and gross of management fees. The study uses time-series data and constructs equally-weighted portfolios of the 42 Swe- dish based actively managed equity mutual funds investing in Sweden for the period 2003- 2013. The portfolios’ excess returns are calculated by estimating the Fama-French three factor model by means of ordinary least squares (OLS) regression analysis. The empirical results show that actively managed equity mutual funds over performed the Fama-French three factor benchmarks by an average annualized net- and gross excess return of 3.60 and 4.67 percent respectively. Sorting out the funds by the performance into deciles, the find- ings indicate that management fees influence the performance of the equity mutual funds in the sample of our study. The conclusion is made such that there is an indication that Swedish equity funds’ managers are able to add value above passive investing.

In 1996, Sloan identified the accruals anomaly, in which the negative relationship between the accruals component of current earnings and subsequent stock returns can be exploited to generate excess returns. One would expect the accruals anomaly to dissipate and ultimately disappear as investors take advantage of the now-public information. However, nearly two decades later, it persists as one of the most prominent and contentious anomalies; its magnitude of current and future excess returns still remain controversial. The main reason for its persistence is that extreme accrual firms possess characteristics that are unappealing to most investors. These characteristics, which include insufficient analyst coverage, high idiosyncratic volatility and the presence of institutional constraints, are generally more pronounced in firms with weak internal controls. This paper finds that the accruals anomaly persists at a higher magnitude in firms with weak internal controls. This higher magnitude of excess returns survives the Fama-French five-factor (2015), the Stambaugh-Yuan four-factor (2017) and the Hou, Xue, and Zhang (2015) q-factor models.

Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 05.09.03 – "Електротехнічні комплекси та системи". – Національний технічний університет "Харківський політехнічний інститут", Харків, 2019. У дисертаційній роботі вирішується важлива науково-технічна проблема підвищення якості електропостачання електротехнічних об'єктів, комплексів та систем і забезпечення їх електромагнітної сумісності шляхом розвитку математичного та апаратного забезпечення систем обліку електроенергії з урахуванням енергетичної ефективності режимів електроспоживання і виявлених порушень меж електромагнітної сумісності з боку постачальника електричної енергії або її споживача. У вступі визначено існуючу проблему і обґрунтовано актуальність теми дисертації, наведено зв'язок роботи з науковими програмами, планами, темами, сформульовано мету і завдання наукового дослідження, розглянуто об'єкт та предмет досліджень, наведено перелік методів дослідження, що застосовувалися для досягнення поставленої мети роботи. Викладено наукову новизну й практичну значущість отриманих результатів, наведено дані про публікації й апробацію результатів роботи, охарактеризовано особистий внесок здобувача, надано відомості про впровадження результатів роботи. У першому розділі на підставі вивчення та систематизації результатів аналізу матеріалів з відкритих джерел сформульовані основні недоліки існуючих методів оцінки якості електропостачання та нормативної бази, яка не дозволяє у повному обсязі вирішувати конфліктні ситуації при виникненні порушень меж електромагнітної сумісності у розрізі електропостачальник-споживач. Також розглянуті методи визначення відповідальності за погіршення якості електричної енергії та окремих її показників. У другому розділі проведено аналіз типової схеми електропостачання, що дозволило зробити висновки та отримати основні числові характеристики системи електропостачання трифазного електротехнічного об'єкту з напругою живлення 10 кВ. За допомогою комп’ютерної моделі показано взаємний вплив декількох споживачів на показники якості напруги у точці приєднання та проаналізовано вплив параметрів системи електропостачання ці показники. Показано, що визначення джерела вищих гармонік за напрямком складової потужності вищої гармоніки не дозволяє гарантовано виділити споживача з нелінійним навантаженням у разі якщо кількість таких споживачів більша за одного. Також проаналізовано сумісність стандартів EN 50160 та IEEE 519 з точки зору норми рівнів гармонійних складових у складі струму та напруги. Отримані результати дозволяють говорити про наявність окремих моментів в яких вищи гармонійні складові струму, що генерує споживач не порушуючи меж стандарту IEEE 519, можуть викликати наявність гармонік напруги що перевищують норми установлені EN 50160. Також зроблено висновки щодо встановлення обмежень генерації вищих гармонійних складових за допомогою нормованих значень опору системи. У третьому розділі запропоновано подальший розвиток математичного апарату визначення коефіцієнтів потужності та втрат, як показників якості електроспоживання, зокрема обґрунтовані визначення інтегральних коефіцієнтів втрат для трифазних трипровідних та чотирьохпровідних мереж. Отримала подальший розвиток теорія "еталонного" споживача. Показано, що в трифазній трипровідній мережі еталонним споживачем незалежно від параметрів напруги є симетричний трикутник постійних активних опорів. Показано, що в трифазній чьотирьохпровідній системі еталонним споживачем незалежно від параметрів напруги є поєднання симетричного трикутника постійних активних опорів і симетричної зірки, опір в гілках якої в стільки ж разів більше опорів трикутника, у скільки разів активний опір провіднику нейтралі більше опору фазних провідників. Вперше запропоновано математичний апарат виділення окремих складових із загальних коефіцієнтів потужностей та втрат за такими типами спотворень як несиметрія, нелінійність, реактивність та нестаціонарність. Запропоновано концепцію еталонного реактивного споживача з умов максимуму потужності або мінімуму втрат при рівності співвідношень перетоків потужності від і до споживача, що дозволяє реалізувати обчислення коефіцієнту реактивності та потужності при довільній формі напруги у однофазних та трифазних мережах. Показано, що при такій постановці еталонний реактивний споживач тяжіє до генерації вищих гармонік і не має зручного аналітичного або чисельного рішення для порівняння з поточним споживачем. Запропоновано концепцію середньореактивного споживача, у якого усі гармоніки мають рівне співвідношення перетікань потужності до і від споживача, що дозволяє реалізувати порівняння режиму електроспоживання поточного споживача з таким середньореактивним. Запропоновано методику оцінки коефіцієнтів втрат і потужності від несиметрії для трифазного споживача при довільній напрузі. Запропоновано методику оцінки співвідношення коефіцієнтів втрат від реактивності і нелінійності споживача шляхом поділу відповідних гармонік струму Фризе у напрямку активної складової. Запропоновано методику оцінки коефіцієнтів втрат і потужності від нестаціонарності споживання. У четвертому розділі проведено аналіз характеру комплексного опору електричної мережі в залежності від параметрів її елементів для типових випадків підключення споживачів на напрузі 10 КВ. Отримана залежність дозволяє говорити про можливе застосування нормованих значень для оцінки пропускної здатності мережі. Набув подальшого розвитку метод вимірювання електричних параметрів трифазної мережі заснований на апроксимації вхідного сигналу сумою гармонійних складових. Особливостями методу є автоматичне підстроювання по частоті і тривалості інтервалу спостереження у заданому діапазоні, використання повного набору напруг фаз (або лінійних) при визначенні частоти з урахуванням їх вагових значень, що дозволяє зменшити похибки вимірювання у складних умовах – при наявності несиметрії, вищих гармонік, аперіодичної складової або при відсутності напруги у окремій фазі. Крім того, метод вимірювання використовує постійну частоту квантування вхідних цифрових даних, що дозволяє спростити апаратну частину приладу. Запропоновано метод обчислення діючих значень з точною прив'язкою до періоду напруги, одержуваного попереднім методом, що дозволяє виключити частотну похибку при вимірюванні незалежно від розташування початку та закінчення інтервалу спостереження відносно відліків вхідного цифрового сигналу. Запропоновано систему обліку електричної енергії з використанням показників якості електричної енергії та ефективності електроспоживання. Особливістю системи є додатковий облік втрат на передачу електричної енергії шляхом порівняння характеристик електроспоживання поточного споживача з такими для еталонного споживача, тобто використання коефіцієнтів втрат або потужності. Такий метод обліку дозволяє коректно тарифікувати всі відхилення в режимах роботи навантаження, такі як реактивність, нелінійність і нестаціонарність. Запропоновано систему штрафних санкцій за погіршення якості електричної енергії, заснована на підрахунку "штрафної" енергії в разі, якщо споживач порушує норми електроспоживання і "нетарифікованої" енергії, в разі коли порушень з боку споживача немає, але якість електроенергії не відповідає нормам. Запропоновано основи тарифікації на базі даної системи обліку електроенергії. У п'ятому розділі експериментально отримані дані, що підтверджують теоретичні положення розділів 3 та 4. Зокрема були реалізовані оцінки якості електроспоживання шляхом порівняння з набором еталонних споживачів. Експеримент показав можливість успішного застосування виділення струму Фрізе і його подальшого аналізу з метою оцінки якості електроспоживання. При цьому можливе паралельне використання його трифазної і однофазної реалізацій для оцінки несиметрії, нелінійності і реактивності відповідно. Запропонована в розділі 3 методика порівняння з еталонним среднереактівним споживачем не виявила себе в якості ефективного інструменту аналізу і не представляється перспективною. У той же час поділ гармонійних складових струму Фрізе у напрямку їх активної складової дозволяє ефективно відстежувати джерело походження струмів вищих гармонік. Визначені вище методи з використанням моделі фрагменту енергосистеми з різними типами навантаження підтвердили коректність розроблених методів оцінки якості електроспоживання. Випробування за допомогою осцилограм, отриманих на реальних трифазних навантаженнях (тягової підстанції) також підтвердило працездатність та ефективність розроблених методів оцінки. В моделях з перевищенням допустимих режимів, використання математичного апарату розробленого в розділі 4 дозволило виявити джерело спотворень, навіть за умови коли одночасно декілька споживачів виступають в якості джерел цих спотворень.
The dissertation on competition of a scientific degree of the doctor of technical sciences on a specialty 05.09.03 - "Electrotechnical complexes and systems". - National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2019. In the dissertation the important scientific and technical problem of increase of quality of power supply of electrotechnical objects, complexes and systems and maintenance of their electromagnetic compatibility by development of mathematical and hardware of systems of the account of the electric power taking into account energy efficiency of modes of power consumption and the revealed infringements of electromagnetic compatibility energy or its consumer. In the introduction the existing problem is defined and the urgency of the dissertation topic is substantiated, the connection of work with scientific programs, plans, themes is given, the purpose and tasks of scientific research are formulated, the object and subject of researches are considered, the list of research methods applied for achievement of the set purpose is given work. The scientific no velty and practical significance of the obtained results are stated, the data on publications and approbation of the results of the work are given, the personal contribution of the applicant is characterized, the information on the implementation of the results of the work is given. In the first section, based on the study and systematization of the results of analysis of materials from open sources, the main shortcomings of existing methods of assessing the quality of electricity supply and regulatory framework, which does not fully resolve conflict situations in violation of electromagnetic compatibility in terms of electricity supplier - consumer. Methods for determining the responsibility for the deterioration of electricity quality and its individual indicators are also considered. The second section analyzes the typical power supply scheme, which allowed to draw conclusions and obtain the main numerical characteristics of the power supply system of a three-phase electrical facility with a supply voltage of 10 kV. The computer model shows the mutual influence of several consumers on the quality indicators of the voltage at the point of connection and analyzes the influence of the parameters of the power supply system, these indicators. It is shown that the definition of the source of higher harmonics in the direction of the component power of the higher harmonic does not guarantee to allocate a consumer with a nonlinear load if the number of such consumers is greater than one. The compatibility of EN 50160 and IEEE 519 standards in terms of the norm of levels of harmonic components in the composition of current and voltage is also analyzed. The obtained results allow to speak about the presence of certain moments in which the higher harmonic components of the current generated by the consumer without violating the IEEE 519 standard can cause the presence of voltage harmonics exceeding the norms set by EN 50160. It is also concluded that the generation of higher harmonic components system resistance values. The third section proposes further development of the mathematical apparatus for determining power and loss coefficients as indicators of power consumption quality, in particular, the determination of integrated loss coefficients for three-phase three-wire and four-wire networks is substantiated. The theory of the "reference" consumer was further developed. It is shown that in a three-phase three-wire network the reference consumer, regardless of the voltage parameters, is a symmetrical triangle of constant active resistances. It is shown that in a three-phase four-wire system the reference consumer, regardless of voltage parameters, is a combination of a symmetric triangle of constant active resistances and a symmetric star, the resistance in the branches of which is as many times the resistance of the triangle as the active resistance of the neutral conductor. For the first time, a mathematical apparatus for selecting individual components from the total power and loss coefficients for such types of distortions as asymmetry, nonlinearity, reactivity and nonstationarity has been proposed. The concept of the reference reactive consumer from the conditions of maximum power or minimum losses at equality of ratios of power flows from and to the consumer is offered, that allows to realize calculation of coefficient of reactivity and power at any form of voltage in single-phase and three-phase networks. It is shown that in such a statement the reference reactive consumer tends to generate higher harmonics and does not have a convenient analytical or numerical solution for comparison with the current consumer. The concept of the average reactive consumer is proposed, in which all harmonics have an equal ratio of power flows to and from the consumer, which allows to compare the current consumption mode of the current consumer with such an average reactive one. A method for estimating the coefficients of loss and power from asymmetry for a three-phase consumer at arbitrary voltage is proposed. A method for estimating the ratio of the coefficients of losses from reactivity and nonlinearity of the consumer by dividing the corresponding harmonics of the Frieze current in the direction of the active component is proposed. A method for estimating the coefficients of losses and power from non-stationary consumption is proposed. In the fourth section the analysis of character of complex resistance of an electric network depending on parameters of its elements for typical cases of connection of consumers on voltage of 10 KV is carried out. The obtained dependence allows us to talk about the possible use of normalized values to estimate network bandwidth. The method of measuring the electrical parameters of a three-phase network based on the approximation of the input signal by the sum of harmonic components has been further developed. Features of the method are automatic adjustment of the frequency and duration of the observation interval in a given range, the use of a complete set of phase voltages (or linear) in determining the frequency taking into account their weight values, which reduces measurement errors in difficult conditions - in the presence of asymmetry, higher harmonics, aperiodic component or in the absence of voltage in a separate phase. In addition, the measurement method uses a constant quantization frequency of the input digital data, which simplifies the hardware of the device. A method of calculating the current values with a precise reference to the voltage period obtained by the previous method is proposed, which eliminates the frequency error in the measurement regardless of the location of the beginning and end of the observation interval relative to the input digital signal. The system of the account of electric energy with use of indicators of quality of electric energy and efficiency of electric consumption is offered. A feature of the system is the additional accounting of losses for the transmission of electricity by comparing the characteristics of electricity consumption of the current consumer with those for the reference consumer, ie the use of loss factors or power. This method of accounting allows you to correctly rate all deviations in the modes of load, such as reactivity, nonlinearity and nonstationarity. A system of penalties for deterioration of electricity quality is proposed, based on the calculation of "penalty" energy if the consumer violates the norms of electricity consumption and "non-tariffed" energy, if there are no violations by the consumer, but the quality of electricity does not meet the norms. The basics of billing on the basis of this electricity metering system are proposed. In the fifth section, the data confirming the theoretical provisions of sections 3 and 4 were experimentally obtained. In particular, estimates of the quality of electricity consumption were implemented by comparison with a set of reference consumers. The experiment showed the possibility of successful application of Frieze current generation and its subsequent analysis to assess the quality of electricity consumption. At the same time parallel use of its three-phase and single-phase implementations for an estimation of asymmetry, nonlinearity and reactivity accordingly is possible. The method of comparison with the reference average reactive consumer proposed in section 3 has not proved to be an effective tool of analysis and does not seem promising. At the same time, the separation of the harmonic components of the Frieze current in the direction of their active component allows you to effectively track the source of currents of higher harmonics. The above methods using the model of a fragment of the power system with different types of load confirmed the correctness of the developed methods for assessing the quality of electricity consumption. Tests using oscillograms obtained on real three-phase loads (traction substation) also confirmed the efficiency and effectiveness of the developed assessment methods. In models with exceeding the permissible modes, the use of the mathematical apparatus developed in Section 4 allowed to identify the source of distortion, even if several consumers act as sources of these distortions at the same time.

Does the 4-factor model have a higher degree of explanation than CAPM and the 3-factor model on the Swedish stock market? The purpose of this thesis is to investigate whether the 4-factor model's ability to explain the systematic risk on the Swedish stock market is better than CAPM and the 3-factor model. Furthermore, we want to investigate whether it is possible to create portfolios based on the 4-factor model that generates excess returns. In addition, we will also compare our results with the results of previous international studies to see what results we get in the Swedish market.

Investors constantly seek information that provides an edge over the market. One of the conventional methods is to find factors which can predict asset returns. In this study we improve the Fama and French Five-Factor model with Regime-Switches, student's t distributions and copula dependencies. We also add price momentum as a sixth factor and add a one-day lag to the factors. The Regime-Switches are obtained from a Hidden Markov Model with conditional Student's t distributions. For the return process we use factor data as input, Student's t distributed residuals, and Student's t copula dependencies. To fit the copulas, we develop a novel approach based on the Expectation-Maximisation algorithm. The results are promising as the quantiles for most of the portfolios show a good fit to the theoretical quantiles. Using a sophisticated Stochastic Programming model, we back-test the predictive power over a 26 year period out-of-sample. Furthermore we analyse the performance of different factors during different market regimes.

Subject background and discussion: In recent decades, issues of human rights, labor and environmental change has been hot topics world wide, which also has influenced the financial market. More and more investors use socially responsible investing (SRI) screens when constructing their portfolios. One form of SRI screen is to choose companies that have satisfied employees. Existing theory says that employee satisfaction is an intangible asset to the firm that will positively affect a firm’s performance in the future. Intangible assets are often unrecognized by the market and thereby not incorporated in the stock price. The efficient market hypothesis has been studied and debated for several decades. Proponents of the EMH argue that all available information is incorporated in the stock price, thus it is not possible to systematically beat the market. However, EMH is controversial, since research has shown different results regarding the possibility to make abnormal return from various investing strategy. Research question: Is it possible to make abnormal returns by investing in a portfolio of worldwide firms with top scores on the SRI screen employee satisfaction? Purpose: The main purpose of this study is to examine investor’s possibility to make abnormal return with controls for multiple risk factors by investing in worldwide firms with top scores in employee satisfaction. One sub-purpose is to examine how the market values intangibles depending on the degree of market efficiency. Another sub-purpose of the study is to test two different portfolio weighting methodologies, equally- and value weighted, and observe the differences between them. Theory: This study deals with the efficient market hypothesis and the concepts of SRI, employee satisfaction, intangible assets and several risk-adjusted measurements. Method: We have chosen to perform a quantitative study with a deductive approach to answer our research question. We used a sample size of 696 firms based on “Great Place to Works”- lists of companies with high employee satisfaction to construct sex portfolios with different holding periods and strategies. These portfolios have been explored and tested significantly with both equally and value weighted methods. Result/Analysis: The study finds significant evidence of an average annual abnormal return of 3,66% and 2,43% for our main portfolio over the market for equally- and value weighted, respectively, using the three-factor model. When adjusting for momentum, thus employing the four-factor model, all the predictive variables still identify strong persistence in the abnormal return, with statistical significance. Conclusion: The results show that it is possible to make abnormal returns, during the observed time period, regardless of the weighing methodology, although the equally weighted received higher abnormal returns. Thus, the market efficiency appears to be in weak form and does not fully value intangibles.

The textbook presents mathematical research methods and models of economic objects and processes designed for the analysis and prediction of economic factors and develop control solutions as in the deterministic conditions, and in conditions of some uncertainty, and dynamics. Each Chapter of the book consists of a theoretical framework, discussed in detail several examples and tasks for independent work. As workbench simulation uses standard office the program Excel and Mathcad. Tutorial focused on independent performance of students individual tasks on disciplines "Economic-mathematical methods" and "Econometrics". Meets the requirements of Federal state educational standard of higher education of the last generation. The publication is intended for students and postgraduate students in economic disciplines. It can also be useful as they perform final qualifying works. The book will be useful for practitioners engaged in the analysis of the current financial and economic condition and future development of firms and businesses.

In an accessible form, the textbook presents the theoretical foundations of physical and mathematical modeling; considers the modeling of mass, heat and momentum transfer processes, the relationship and analogy between them; studies the theory of similarity, its application in modeling, models of the structure of flows in apparatuses. Experimental-statistical and experimental-analytical modeling methods are also described, which include "black box" methods, planning passive, active full and fractional factor experiments, and adjusting models based on the results of the experiment. At the same time, modeling of chemical reactors, methods of optimization of chemical-technological processes, their selection, comparison and application examples are considered. Examples of modeling and optimization of processes in chemical, petrochemical and biotechnology on a computer in Excel and MathCAD environments are given. The appendices provide the basics of working in the MathCAD environment and elements of matrix algebra. Meets the requirements of the Federal state educational standards of higher education of the latest generation. It is intended for bachelors who are trained for the chemical, petrochemical, food, textile and light industries. It can be useful for specialists and undergraduates, as well as for scientists, engineers and postgraduates dealing with the problem under consideration.

NOx formation during the combustion process occurs mainly through the oxidation of nitrogen in the combustion air (thermal NOx) and through oxidation of nitrogen with the fuel (prompt NOx). The present study aims to investigate numerically the problem of NOx pollution using a model of combustion chamber with 200 kW swirl burner utilizing propane as fuel. The importance of this problem is mainly due to its relation to the pollutants produced by boiler furnaces and gas turbines, which used widely in thermal industrial plants. Governing conservation equations of mass, momentum and energy, and equations representing the transport of species concentrations, turbulence, combustion and radiation modeling in addition to NOx modeling equations were solved together to present temperature and OH distribution inside the combustion chamber, and the NOx concentration at the combustion chamber exit, at various operating conditions of fuel to air ratio. In particular, the simulation provided more insight on the correlation between the peak flame temperature and the thermal NOx concentration. The results have shown that the peak flame temperature and NOx concentration decrease as the excess air factor λ increases. When considering a fixed value of mass flow rate of fuel, the results show that increasing λ results in a maximum value of thermal NOx concentration at the exit of the combustion chamber at λ = 1.05. As the combustion air temperature increases, and the thermal NOx concentration increases sharply. However, when λ exceeds this value NOx concentration starts to decrease due to the combustion air temperature decrease.

Borderline hypertension causes mortality and morbidity rates similar to those associated with estabilished hypertension. However, there is no univocal guideline for its therapeutic management. Hypercoagulability in hypertension has been demonstrated. The aim of our study was to evaluate some coagulation factors in agroup of patients affected by borderlinehypertension. The following tests were carried out: PT and PTT, Factor VIII coagulant activity, FVIII antigen and FVIII ristocetin cofactor, Factor XII and Factor XI activities. These tests were selected for their relationship to the contact coagulative activation near the vascular wall. In our patients statistically significant higher FVIII and FXII coagulant activities than normal control subjects were found. Moreover, an evident even though not statistically significant PTT shortening was seen. Other tests taken into consideration were all within normal limits. Our results suggest that an increased FVIII and FXII synthesis and/or release is present, and an activated coagulation system exists in borderline hypertension. Furthermore, it is not clear why an excess of FVIII:C over FVIIIR:Ag and FVIIIR:RCof was found in our patients. In conclusion, an activation of haemostatic mechanism was found in borderline hypertension. The young age of patients and the absence of evident hypertensive angiopathy are in agreement with an overactivity of blood vessel tone. Haemostatic activation could be an useful marker in favour of the precious management of patients with borderline hypertension.

Standard salinity management theory, derived from blending thermodynamic and semi- empirical considerations leads to an erroneous perception regarding compensative interaction among salinity stress factors. The current approach treats matric and osmotic components of soil water potential separately and then combines their effects to compute overall response. With deficit water a severe yield decrease is expected under high salinity, yet little or no reduction is predicted for excess irrigation, irrespective of salinity level. Similarly, considerations of competition between chloride and nitrate ions have lead to compensation hypothesis and to application of excess nitrate under saline conditions. The premise of compensative interaction of growth factors behind present practices (that an increase in water application alleviates salinity stress) may result in collateral environmental damage. Over-irrigation resulting in salinization and elevated ground water threatens productivity on a global scale. Other repercussions include excessive application of nitrate to compensate for salinity, unwillingness to practice deficit irrigation with saline water, and under-utilization of marginal water. The objectives for the project were as follows: 1) To develop a database for model parameterization and validation by studying yield and transpiration response to water availability, excessive salinity and salt composition. 2) To modify the root sink terms of an existing mechanism-based model(s) of water flow, transpiration, crop yield, salt transport, and salt chemistry. 3) To develop conceptual and quantitative models of ion uptake that considers the soil solution concentration and composition. 4) To develop a conceptual and quantitative models of effects of NaCl and boron accumulation on yield and transpiration. 5) To add a user interface to the water flow, transpiration, crop yield, salt transport, chemistry model to make it easy for others to use. We conducted experiments in field plots and lysimeters to study biomass production and transpiration of com (Zeamays cv. Jubilee), melon (Cucumismelo subsp. melo cv. Galia), tomato (Lycopersiconesculentum Mill. cv. 5656), onion (Alliumcepa L. cv. HA 944), and date palms (Phoenix Dactylifera L. cv. Medjool) under salinity combined with water or with nitrate (growth promoters) or with boron (growth inhibitor). All factors ranged from levels not limiting to plant function to severe inhibition. For cases of combined salinity with water stress, or excess boron, we observed neither additive nor compensative effects on plant yield and transpiration. In fact, yield and transpiration at each combination of the various factors were primarily controlled by one of them, the most limiting factor to plant activity. We proposed a crop production model of the form Yr = min{gi(xi), where Yr = Yi ym-1 is relative yield,Ym is the maximum yield obtained in each experiment, Xi is an environmental factor, gi is a piecewise-linear response function, Yi is yield of a particular treatment. We selected a piecewise-linear approach because it highlights the irrigation level where the response to one factor ceases and a second factor begins. The production functions generate response "envelopes" containing possible yields with diagonal lines represent response to Xi alone and the lines parallel to the X-axis represent response to salinity alone. A multiplicative model was also derived approximating the limiting behaviour for incorporation in a hydrochemical model. The multiplicative model was selected because the response function was required to be continuous. The hydrochemical model was a better predictor of field-measured water content and salt profiles than models based on an additive and compensative model of crop response to salinity and water stress.

1.1 Macroeconomic summary Economic recovery has consistently outperformed the technical staff’s expectations following a steep decline in activity in the second quarter of 2020. At the same time, total and core inflation rates have fallen and remain at low levels, suggesting that a significant element of the reactivation of Colombia’s economy has been related to recovery in potential GDP. This would support the technical staff’s diagnosis of weak aggregate demand and ample excess capacity. The most recently available data on 2020 growth suggests a contraction in economic activity of 6.8%, lower than estimates from January’s Monetary Policy Report (-7.2%). High-frequency indicators suggest that economic performance was significantly more dynamic than expected in January, despite mobility restrictions and quarantine measures. This has also come amid declines in total and core inflation, the latter of which was below January projections if controlling for certain relative price changes. This suggests that the unexpected strength of recent growth contains elements of demand, and that excess capacity, while significant, could be lower than previously estimated. Nevertheless, uncertainty over the measurement of excess capacity continues to be unusually high and marked both by variations in the way different economic sectors and spending components have been affected by the pandemic, and by uneven price behavior. The size of excess capacity, and in particular the evolution of the pandemic in forthcoming quarters, constitute substantial risks to the macroeconomic forecast presented in this report. Despite the unexpected strength of the recovery, the technical staff continues to project ample excess capacity that is expected to remain on the forecast horizon, alongside core inflation that will likely remain below the target. Domestic demand remains below 2019 levels amid unusually significant uncertainty over the size of excess capacity in the economy. High national unemployment (14.6% for February 2021) reflects a loose labor market, while observed total and core inflation continue to be below 2%. Inflationary pressures from the exchange rate are expected to continue to be low, with relatively little pass-through on inflation. This would be compatible with a negative output gap. Excess productive capacity and the expectation of core inflation below the 3% target on the forecast horizon provide a basis for an expansive monetary policy posture. The technical staff’s assessment of certain shocks and their expected effects on the economy, as well as the presence of several sources of uncertainty and related assumptions about their potential macroeconomic impacts, remain a feature of this report. The coronavirus pandemic, in particular, continues to affect the public health environment, and the reopening of Colombia’s economy remains incomplete. The technical staff’s assessment is that the COVID-19 shock has affected both aggregate demand and supply, but that the impact on demand has been deeper and more persistent. Given this persistence, the central forecast accounts for a gradual tightening of the output gap in the absence of new waves of contagion, and as vaccination campaigns progress. The central forecast continues to include an expected increase of total and core inflation rates in the second quarter of 2021, alongside the lapse of the temporary price relief measures put in place in 2020. Additional COVID-19 outbreaks (of uncertain duration and intensity) represent a significant risk factor that could affect these projections. Additionally, the forecast continues to include an upward trend in sovereign risk premiums, reflected by higher levels of public debt that in the wake of the pandemic are likely to persist on the forecast horizon, even in the context of a fiscal adjustment. At the same time, the projection accounts for the shortterm effects on private domestic demand from a fiscal adjustment along the lines of the one currently being proposed by the national government. This would be compatible with a gradual recovery of private domestic demand in 2022. The size and characteristics of the fiscal adjustment that is ultimately implemented, as well as the corresponding market response, represent another source of forecast uncertainty. Newly available information offers evidence of the potential for significant changes to the macroeconomic scenario, though without altering the general diagnosis described above. The most recent data on inflation, growth, fiscal policy, and international financial conditions suggests a more dynamic economy than previously expected. However, a third wave of the pandemic has delayed the re-opening of Colombia’s economy and brought with it a deceleration in economic activity. Detailed descriptions of these considerations and subsequent changes to the macroeconomic forecast are presented below. The expected annual decline in GDP (-0.3%) in the first quarter of 2021 appears to have been less pronounced than projected in January (-4.8%). Partial closures in January to address a second wave of COVID-19 appear to have had a less significant negative impact on the economy than previously estimated. This is reflected in figures related to mobility, energy demand, industry and retail sales, foreign trade, commercial transactions from selected banks, and the national statistics agency’s (DANE) economic tracking indicator (ISE). Output is now expected to have declined annually in the first quarter by 0.3%. Private consumption likely continued to recover, registering levels somewhat above those from the previous year, while public consumption likely increased significantly. While a recovery in investment in both housing and in other buildings and structures is expected, overall investment levels in this case likely continued to be low, and gross fixed capital formation is expected to continue to show significant annual declines. Imports likely recovered to again outpace exports, though both are expected to register significant annual declines. Economic activity that outpaced projections, an increase in oil prices and other export products, and an expected increase in public spending this year account for the upward revision to the 2021 growth forecast (from 4.6% with a range between 2% and 6% in January, to 6.0% with a range between 3% and 7% in April). As a result, the output gap is expected to be smaller and to tighten more rapidly than projected in the previous report, though it is still expected to remain in negative territory on the forecast horizon. Wide forecast intervals reflect the fact that the future evolution of the COVID-19 pandemic remains a significant source of uncertainty on these projections. The delay in the recovery of economic activity as a result of the resurgence of COVID-19 in the first quarter appears to have been less significant than projected in the January report. The central forecast scenario expects this improved performance to continue in 2021 alongside increased consumer and business confidence. Low real interest rates and an active credit supply would also support this dynamic, and the overall conditions would be expected to spur a recovery in consumption and investment. Increased growth in public spending and public works based on the national government’s spending plan (Plan Financiero del Gobierno) are other factors to consider. Additionally, an expected recovery in global demand and higher projected prices for oil and coffee would further contribute to improved external revenues and would favor investment, in particular in the oil sector. Given the above, the technical staff’s 2021 growth forecast has been revised upward from 4.6% in January (range from 2% to 6%) to 6.0% in April (range from 3% to 7%). These projections account for the potential for the third wave of COVID-19 to have a larger and more persistent effect on the economy than the previous wave, while also supposing that there will not be any additional significant waves of the pandemic and that mobility restrictions will be relaxed as a result. Economic growth in 2022 is expected to be 3%, with a range between 1% and 5%. This figure would be lower than projected in the January report (3.6% with a range between 2% and 6%), due to a higher base of comparison given the upward revision to expected GDP in 2021. This forecast also takes into account the likely effects on private demand of a fiscal adjustment of the size currently being proposed by the national government, and which would come into effect in 2022. Excess in productive capacity is now expected to be lower than estimated in January but continues to be significant and affected by high levels of uncertainty, as reflected in the wide forecast intervals. The possibility of new waves of the virus (of uncertain intensity and duration) represents a significant downward risk to projected GDP growth, and is signaled by the lower limits of the ranges provided in this report. Inflation (1.51%) and inflation excluding food and regulated items (0.94%) declined in March compared to December, continuing below the 3% target. The decline in inflation in this period was below projections, explained in large part by unanticipated increases in the costs of certain foods (3.92%) and regulated items (1.52%). An increase in international food and shipping prices, increased foreign demand for beef, and specific upward pressures on perishable food supplies appear to explain a lower-than-expected deceleration in the consumer price index (CPI) for foods. An unexpected increase in regulated items prices came amid unanticipated increases in international fuel prices, on some utilities rates, and for regulated education prices. The decline in annual inflation excluding food and regulated items between December and March was in line with projections from January, though this included downward pressure from a significant reduction in telecommunications rates due to the imminent entry of a new operator. When controlling for the effects of this relative price change, inflation excluding food and regulated items exceeds levels forecast in the previous report. Within this indicator of core inflation, the CPI for goods (1.05%) accelerated due to a reversion of the effects of the VAT-free day in November, which was largely accounted for in February, and possibly by the transmission of a recent depreciation of the peso on domestic prices for certain items (electric and household appliances). For their part, services prices decelerated and showed the lowest rate of annual growth (0.89%) among the large consumer baskets in the CPI. Within the services basket, the annual change in rental prices continued to decline, while those services that continue to experience the most significant restrictions on returning to normal operations (tourism, cinemas, nightlife, etc.) continued to register significant price declines. As previously mentioned, telephone rates also fell significantly due to increased competition in the market. Total inflation is expected to continue to be affected by ample excesses in productive capacity for the remainder of 2021 and 2022, though less so than projected in January. As a result, convergence to the inflation target is now expected to be somewhat faster than estimated in the previous report, assuming the absence of significant additional outbreaks of COVID-19. The technical staff’s year-end inflation projections for 2021 and 2022 have increased, suggesting figures around 3% due largely to variation in food and regulated items prices. The projection for inflation excluding food and regulated items also increased, but remains below 3%. Price relief measures on indirect taxes implemented in 2020 are expected to lapse in the second quarter of 2021, generating a one-off effect on prices and temporarily affecting inflation excluding food and regulated items. However, indexation to low levels of past inflation, weak demand, and ample excess productive capacity are expected to keep core inflation below the target, near 2.3% at the end of 2021 (previously 2.1%). The reversion in 2021 of the effects of some price relief measures on utility rates from 2020 should lead to an increase in the CPI for regulated items in the second half of this year. Annual price changes are now expected to be higher than estimated in the January report due to an increased expected path for fuel prices and unanticipated increases in regulated education prices. The projection for the CPI for foods has increased compared to the previous report, taking into account certain factors that were not anticipated in January (a less favorable agricultural cycle, increased pressure from international prices, and transport costs). Given the above, year-end annual inflation for 2021 and 2022 is now expected to be 3% and 2.8%, respectively, which would be above projections from January (2.3% and 2,7%). For its part, expected inflation based on analyst surveys suggests year-end inflation in 2021 and 2022 of 2.8% and 3.1%, respectively. There remains significant uncertainty surrounding the inflation forecasts included in this report due to several factors: 1) the evolution of the pandemic; 2) the difficulty in evaluating the size and persistence of excess productive capacity; 3) the timing and manner in which price relief measures will lapse; and 4) the future behavior of food prices. Projected 2021 growth in foreign demand (4.4% to 5.2%) and the supposed average oil price (USD 53 to USD 61 per Brent benchmark barrel) were both revised upward. An increase in long-term international interest rates has been reflected in a depreciation of the peso and could result in relatively tighter external financial conditions for emerging market economies, including Colombia. Average growth among Colombia’s trade partners was greater than expected in the fourth quarter of 2020. This, together with a sizable fiscal stimulus approved in the United States and the onset of a massive global vaccination campaign, largely explains the projected increase in foreign demand growth in 2021. The resilience of the goods market in the face of global crisis and an expected normalization in international trade are additional factors. These considerations and the expected continuation of a gradual reduction of mobility restrictions abroad suggest that Colombia’s trade partners could grow on average by 5.2% in 2021 and around 3.4% in 2022. The improved prospects for global economic growth have led to an increase in current and expected oil prices. Production interruptions due to a heavy winter, reduced inventories, and increased supply restrictions instituted by producing countries have also contributed to the increase. Meanwhile, market forecasts and recent Federal Reserve pronouncements suggest that the benchmark interest rate in the U.S. will remain stable for the next two years. Nevertheless, a significant increase in public spending in the country has fostered expectations for greater growth and inflation, as well as increased uncertainty over the moment in which a normalization of monetary policy might begin. This has been reflected in an increase in long-term interest rates. In this context, emerging market economies in the region, including Colombia, have registered increases in sovereign risk premiums and long-term domestic interest rates, and a depreciation of local currencies against the dollar. Recent outbreaks of COVID-19 in several of these economies; limits on vaccine supply and the slow pace of immunization campaigns in some countries; a significant increase in public debt; and tensions between the United States and China, among other factors, all add to a high level of uncertainty surrounding interest rate spreads, external financing conditions, and the future performance of risk premiums. The impact that this environment could have on the exchange rate and on domestic financing conditions represent risks to the macroeconomic and monetary policy forecasts. Domestic financial conditions continue to favor recovery in economic activity. The transmission of reductions to the policy interest rate on credit rates has been significant. The banking portfolio continues to recover amid circumstances that have affected both the supply and demand for loans, and in which some credit risks have materialized. Preferential and ordinary commercial interest rates have fallen to a similar degree as the benchmark interest rate. As is generally the case, this transmission has come at a slower pace for consumer credit rates, and has been further delayed in the case of mortgage rates. Commercial credit levels stabilized above pre-pandemic levels in March, following an increase resulting from significant liquidity requirements for businesses in the second quarter of 2020. The consumer credit portfolio continued to recover and has now surpassed February 2020 levels, though overall growth in the portfolio remains low. At the same time, portfolio projections and default indicators have increased, and credit establishment earnings have come down. Despite this, credit disbursements continue to recover and solvency indicators remain well above regulatory minimums. 1.2 Monetary policy decision In its meetings in March and April the BDBR left the benchmark interest rate unchanged at 1.75%.

According to federal law, routine commercial vehicles must adhere to certain limits on their load configuration in order to operate legally on interstate highways. However, states may allow for heavier or different load configurations provided that bridges on the state and county highway system are load rated and, if necessary, posted with vehicles that appropriately represent these loads. The state of Indiana allows several classes of vehicles to operate with loads that exceed federal limits, and, presently, several LFD design loads are used to represent these exceptions as state legal loads. This study evaluates the MBE rating loads for their ability to encompass Indiana’s exception vehicles and recommends a set of state rating loads which can replace the current state legal loads and, combined with the MBE rating loads, satisfactorily encompass the load effects due to these exceptions. Comparing moment and shear envelopes on a representative set of bridges, the MBE rating vehicles were found to be insufficient for representing Indiana’s exception vehicles. Three new rating loads are proposed which encompass the exception vehicles efficiently and represent realistic legal loads. Conversely, acceptable HS-20 rating factors are also provided as an alternative to the adoption of these new vehicles. These rating factors, all 1.0 or greater, can ensure a similar level of safety by requiring a specific amount of excess capacity for the HS-20 design load.

Review question / Objective: Gallbladder cancer is a rare tumor that is mostly advanced once detected. The efficacy of surgical treatment is still controversial. Therefore, primary prevention of gallbladder cancer is important. There are many studies on risk factors for gallbladder cancer, but at present it is difficult to identify independent risk factors for gallbladder cancer, except for a history of symptomatic chronic cholecystitis and malignant transformation of a single polyp. Laparoscopic cholecystectomy is popular worldwide and can be a preventive procedure for gallbladder cancer in addition to resolving benign lesions. This study makes a meta-analysis of the latest research results exploring the risk factors of gallbladder cancer in the last decade , expecting to provide evidence-based medical support for the prevention of gallbladder cancer at the clinical level, and to provide some ideas to guide the surgical indications for LC and future research related to gallbladder cancer. Subject of study: Gallbladder cancer. Study content: Risk factors. Type of study: case-control or cohort study. Extract the value: OR, HR, RR.

Latin American and Caribbean countries will face significant increases in future health expenditures. A variety of factors are responsible - population growth and aging, the epidemiological transition to noncommunicable diseases (NCDs), and economic growth and technology, among others. Increasing health expenditures are particularly concerning to countries in Latin America and the Caribbean (LAC) given growing levels of debt, insufficient fiscal revenues, and high out-of-pocket payments. The projected average annual per capita CHE growth rate from 2018-2050 is slightly higher in Latin American countries (3.2%) than in the Caribbean (2.4%). The share of health expenditure in GDP is projected to increase to 2030 in all LAC countries except for Guyana. The effect of demographics and epidemiology on health spending growth are more modest. Among strategies to control NCD risk factors, a focus on hypertension control generally had the strongest effect on restraining CHE growth except in countries where smoking is particularly prevalent. The main driver of health expenditure growth is economic growth and technology, demonstrating the importance of adopting policies such as explicit prioritization systems and benefit plans that establish common rules for payers and providers that encourage cost-effective decisions. The underlying model for making projections and analyzing alternative scenarios is publicly available.

A model of the energy balance of a transpiring crop in a greenhouse was developed in a format suitable for use in climate control algorithms aimed at dissipating excess heat during the warm periods. The model's parameters use external climatic variables as input. It incorporates radiation and convective transfer functions related to the operation of control devices like shading screens, vents, fans and enhanced evaporative cooling devices. The model identified the leaf boundary-layer resistance and the leaf stomatal and cuticular resistance as critical parameters regulating the temperature of the foliage. Special experiments evaluated these variables and established their relation to environmental factors. The research established that for heat load conditions in Mediterranean and arid climates transpiring crops maintained their foliage temperature within the range allowing high productivity. Results specify that a water supply ensuring minimum leaf resistance to remain below 100 s m-1, and a ventilation rate of 30 air exchanges per hour, are the conditions needed to achieve self cooling. Two vegetable crops, tomato and sweet pepper fulfilled maintained their leaf resistance within the prescribed range at maturity, i.e., during the critical warm season. The research evaluates the effects of additional cooling obtained from wet pad systems and spray wetting of foliage.

In June 2014, Hambrey Consulting successfully responded to a call for tenders for research to undertake a pilot assessment of the potential economic and associated benefits of establishing minimum market landing size (MMLS) in excess of minimum legal landing size (MLS) for shellfish; and to evaluate if such an intervention could be undertaken at a regional level. The project was originally conceived as including 3 case studies, but the scope of the research led us to focus mainly on the trawl and creel fishery for Nephrops prosecuted by the fleet based in Skye and SW Ross. The basic framework for the assessment approach was to: Develop an economic profile of the case study area and its fishing fleet; Review and synthesise existing data on size profile of the catch, the factors that affect size, including costs associated with individual (vessel) actions or strategies to increase the size profile of the catch; Analyse market and market trends, and the prices for different sizes of product; Develop economic models of representative fishing enterprises, taking account of the relationships between costs and returns and the size profile of the catch; Use plausible scenarios to explore likely short term economic consequences of any changes in MMLS; Use yield and utility per recruit analysis to explore possible yield benefits associated with increased MMLS.

Our previous work indicated that suspension-cultured plant cells show remarkable flexibility in altering cell wall structure in response either to growth on saline medium or in the presence of the cellulose synthesis inhibitor 2,-6-dichlorobenzonitrile (DCB). We have continued to analyze the structure of these modified cell walls to understand how the changes modify wall strength, porosity, and ability to expand. The major load-bearing network in the walls of DCB-adapted dicot cells that lack a substantial cellulose-xyloglucan network is comprised of Ca2+-bridged pectates; these cells also have an unusual and abundant soluble pectic fraction. By contrast, DCB-adapted barley, a graminaceous monocot achieves extra wall strength by enhanced cross-linking of its non-cellulosic polysaccharide network via phenolic residues. Our results have also shed new light on normal wall stucture: 1) the cellulose-xyloglucan network may be independent of other wall networks in dicot primary walls and accounts for about 70% of the total wall strength; 2) the pectic network in dicot walls is the primary determinant of wall porosity; 3) both wall strength and porosity in graminaceous monocot primary walls is greatly influenced by the degree of phenolic cross-linking between non-cellulosic polysaccharides; and 4) the fact that the monocot cells do not secrete excess glucuronoarabinoxylan and mixed-linked glucan in response to growth on DCB, suggests that these two non-cellulosic polymers do not normally interact with cellulose in a manner similar to xyloglucan. We also attempted to understand the factors which limit cell expansion during growth of cells in saline medium. Analyses of hydrolytic enzyme activities suggest that xyloglucan metabolism is not repressed during growth on NaCl. Unlike non-adapted cells, salt-adapted cells were found to lack pectin methyl esterase, but it is not clear how this difference could relate to alterations in wall expansibility. Salt-adaped cell walls contain reduced hyp and secrete two unique PRPP-related proteins suggesting that high NaCl inhibits the cross-linking of these proteins into the walls, a finding that might relate to their altered expansibility.

The long-term goal of this research is to understand how pollen cope with stress, and identify genes that can be manipulated in crop plants to improve reproductive success during heat stress. The specific aims were to: 1) Compare heat stress dependent changes in gene expression between wild type pollen, and mutants in which pollen are heat sensitive (cngc16) or heat tolerant (apx2-1). 2) Compare cngc16 and apx2 mutants for differences in heat-stress triggered changes in ROS, cNMP, and Ca²⁺ transients. 3) Expand a mutant screen for pollen with increased or decreased thermo-tolerance. These aims were designed to provide novel and fundamental advances to our understanding of stress tolerance in pollen reproductive development, and enable research aimed at improving crop plants to be more productive under conditions of heat stress. Background: Each year crop yields are severely impacted by a variety of stress conditions, including heat, cold, drought, hypoxia, and salt. Reproductive development in flowering plants is highly sensitive to hot or cold temperatures, with even a single hot day or cold night sometimes being fatal to reproductive success. In many plants, pollen tube development and fertilization is often the weakest link. Current speculation about global climate change is that most agricultural regions will experience more extreme environmental fluctuations. With the human food supply largely dependent on seeds, it is critical that we consider ways to improve stress tolerance during fertilization. The heat stress response (HSR) has been intensively studied in vegetative tissues, but is poorly understood during reproductive development. A general paradigm is that HS is accompanied by increased production of reactive oxygen species (ROS) and induction of ROS-scavenging enzymes to protect cells from excess oxidative damage. The activation of the HSR has been linked to cytosolic Ca²⁺ signals, and transcriptional and translational responses, including the increased expression of heat shock proteins (HSPs) and antioxidative pathways. The focus of the proposed research was on two mutations, which have been discovered in a collaboration between the Harper and Miller labs, that either increase or decrease reproductive stress tolerance in a model plant, Arabidopsis thaliana (i.e., cngc16--cyclic nucleotide gated channel 16, apx2-1--ascorbate peroxidase 2,). Major conclusions, solutions, achievements. Using RNA-seq technology, the expression profiles of cngc16 and apx2 pollen grains were independently compared to wild type under favourable conditions and following HS. In comparison to a wild type HSR, there were 2,776 differences in the transcriptome response in cngc16 pollen, consistent with a model in which this heat-sensitive mutant fails to enact or maintain a normal wild-type HSR. In a comparison with apx2 pollen, there were 900 differences in the HSR. Some portion of these 900 differences might contribute to an improved HSR in apx2 pollen. Twenty-seven and 42 transcription factor changes, in cngc16 and apx2-1, respectively, were identified that could provide unique contributions to a pollen HSR. While we found that the functional HS-dependent reprogramming of the pollen transcriptome requires specific activity of CNGC16, we identified in apx2 specific activation of flavonol-biosynthesis pathway and auxin signalling that support a role in pollen thermotolerance. Results from this study have identified metabolic pathways and candidate genes of potential use in improving HS tolerance in pollen. Additionally, we developed new FACS-based methodology that can quantify the stress response for individual pollen in a high-throughput fashion. This technology is being adapted for biological screening of crop plant’s pollen to identify novel thermotolerance traits. Implications, both scientific and agricultural. This study has provided a reference data on the pollen HSR from a model plant, and supports a model that the HSR in pollen has many differences compared to vegetative cells. This provides an important foundation for understanding and improving the pollen HSR, and therefor contributes to the long-term goal of improving productivity in crop plants subjected to temperature stress conditions. A specific hypothesis that has emerged from this study is that pollen thermotolerance can be improved by increasing flavonol accumulation before or during a stress response. Efforts to test this hypothesis have been initiated, and if successful have the potential for application with major seed crops such as maize and rice.