Academic literature on the topic 'Biological psychology not elsewhere classified'

One hundred Vietnam-era male veterans in a Veterans Administration. 28-day inpatient alcohol treatment program were classified into combat and noncombat groups according to whether they served in Vietnam or elsewhere during the Vietnam conflict. The MMPI scores of the two groups were compared according to a diagnostic decision-rule developed by Keane, Malloy, and Fairbank in 1984 for posttraumatic stress disorder. Chi-squared analysis showed that the combat group passed the decision-rule in significantly higher numbers than the noncombat group. The results provide evidence that the F-2-8 decision-rule to determine this diagnosis applies to alcoholic as well as nonalcoholic populations.

AbstractBaron has provided some examples of nonconsequentialism in decision making and describes them as biases; these may be the remnants of the biological origin of decision making. One may argue that decisions are made on the basis not of rationality but affective processes. Behavior follows the trend toward maximizing pleasure. This mechanism might explain apparent nonconsequentialism.

Abstract The purpose of the study was to compare the visuospatial decision-making error scores related to the perception of biological motion of individuals categorized as field dependent or field independent. A sample of 69 participants aged 18-27 years (M = 21.91, SD = 2.39) that included 33 males and 36 females completed the experiment. Cognitive style was assessed using the Group Embedded Figure Test. Perception of biological motion was evaluated using two different point-light stimuli developed from video images of a ballet dancer’s performance of a correct and incorrect turn in the fifth position. The results showed that individuals classified as field independent made significantly fewer visuospatial processing errors. The findings are considered and discussed in relation to theoretical perspectives associated with both cognitive processing and cognitive style.

Cognitive neuroscience is challenging the Anglo-American approach to criminal responsibility. Critiques, in this issue and elsewhere, are pointing out the deeply flawed psychological assumptions underlying the legal tests for mental incapacity. The critiques themselves, however, may be flawed in looking, as the tests do, at the psychology of the offender. Introducing the strategic structure of punishment into the analysis leads us to consider the psychology of the punisher as the critical locus of cognition informing the responsibility rules. Such an approach both helps to make sense of the counterfactual assumptions about offender psychology embodied in the law and provides a possible explanation for the human conviction of the existence of free will, at least in others.

The biopsychosocial model treats pain as resulting from a complex interaction of biological, psychological, and social factors. Individual differences in approaches to coping with pain-related symptoms are important determinants of pain-related outcomes, and are often classified under the “psychological” category within the biopsychosocial model. However, engagement in various cognitive, affective, and behavioral pain-coping strategies appears to exert biological effects, which we review here. Pain-coping activities such as catastrophizing, distracting oneself from pain sensations, or reappraisal of pain may exert effects on activity in a variety of pain-processing and pain-modulatory circuits within the brain, as well affect the functioning of neuromuscular, immune, and neuroendocrine systems. The interface between pain-related neurobiology and the use of specific pain-coping techniques represents an important avenue for future pain research.

“Minimal cognition” is used in certain sectors of the cognitive sciences to make a kind of ontological claim that may be unique in the biological sciences: that a function operating in organisms living today is not a fully fledged version of that function (the nature of which remains unspecified), but, rather, exhibits the minimal requirements for whatever it is, properly conceived. Evidence suggests that elsewhere in the life sciences, deployment of minimizing qualifiers relative to a biological function appears largely restricted to two scenarios: first, attenuated functioning and, second, evolution of the function, real or synthetic. The article argues that “minimal cognition” and “proto-cognitive” were introduced at the turn of this century by cognitive researchers seeking to learn directly from evolved behavior, ecology and physiology. A terminological straitjacket imposed on the central object of cognitive science at its beginning necessitated the move. An alternative terminology is proposed, based on a phyletically neutral definition of cognition as a biological function; a candidate mechanism is explored; and a bacterial example presented. On this story, cognition is like respiration: ubiquitously present, from unicellular life to blue whales and every form of life in between, and for similar reasons: staying alive requires it.

After a long debate there is now growing agreement that implicit and explicit achievement motivation can be seen as distinct constructs. One of their major differences lies in their predictive validity, which supposedly differs depending on the setting. Empirical evidence exists to the effect that different explicit measures based on different theoretical concepts build one construct. For implicit measures, however, such evidence is lacking. Thus, scores on three implicit and three explicit achievement motivation measures, an intelligence test, and a Big 5 questionnaire were obtained (N = 150) as well as two criteria. The explicit achievement motivation measures were classified as being based either on Murray’s or on McClelland’s theory. Results replicate the idea of a common construct for explicit measures but not for implicit measures. The assumed predictions did not occur for all tests and disappeared when controlling for intelligence.

AbstractObjective:To determine whether volumetric measures of the hippocampus, entorhinal cortex, and other cortical measures can differentiate between cognitively normal individuals and subjects with mild cognitive impairment (MCI).Method:Magnetic resonance imaging (MRI) data from 46 cognitively normal subjects and 50 subjects with MCI as part of the Boston University Alzheimer’s Disease Center research registry and the Alzheimer’s Disease Neuroimaging Initiative were used in this cross-sectional study. Cortical, subcortical, and hippocampal subfield volumes were generated from each subject’s MRI data using FreeSurfer v6.0. Nominal logistic regression models containing these variables were used to identify subjects as control or MCI.Results:A model containing regions of interest (superior temporal cortex, caudal anterior cingulate, pars opercularis, subiculum, precentral cortex, caudal middle frontal cortex, rostral middle frontal cortex, pars orbitalis, middle temporal cortex, insula, banks of the superior temporal sulcus, parasubiculum, paracentral lobule) fit the data best (R2= .7310, whole model test chi-square = 97.16,p< .0001).Conclusions:MRI data correctly classified most subjects using measures of selected medial temporal lobe structures in combination with those from other cortical areas, yielding an overall classification accuracy of 93.75%. These findings support the notion that, while volumes of medial temporal lobe regions differ between cognitively normal and MCI subjects, differences that can be used to distinguish between these two populations are present elsewhere in the brain.

AbstractIn the field of psychopathology there is still a lack of consensus on how mental disorders, such as depression, should be classified and explained. Many of our current classifications suffer from disorder heterogeneity and are conceptually vague. While some researchers have argued that mental disorders are better explained from a biological perspective, others have made the case for pluralistic and integrative explanations. Using depression as an extended example, we explore the challenges in classifying and explaining psychopathology. We begin by evaluating the current approaches to classification, including frameworks for what we consider a mental disorder. This is followed by a detailed summary of current explanatory perspectives in psychiatry. The relationship between classification and explanation presents unique theoretical challenges in understanding mental disorders. We suggest that by adjusting our focus from understanding syndromes to clinical phenomena we can advance our understanding of mental disorders.

The use of lipid profiles from the immobilised alga Selenastrum capricornuizim was investigated as a potential indicator of heavy metal pollution in freshwater environments. The toxicity of Cu", Zn 2 and Cd2t on algal growth was determined and the effective concentration inhibiting specific growth rate by 50 % (EC5 0) for each metal was found to be 124 pM Cu, 20 pM Zn and 5.7 pM Cd respectively. The Cu 24 EC50 value for immobilised cells was also shown to be 124 j.tM, suggesting that Cu exhibits similar toxic effects on growth in both free and immobilised cells. Studies of the effects of temperature and heavy metal exposure (Cu21, Zn 2 and Cd2 +) on S. caprzcornutum demonstrated that these factors altered the fatty acid and free sterol composition of free algal cells in batch culture. A shift in temperature from 25°C to 10°C led to an increase in the relative proportion of oleate and decrease in linoleate and parinate (18:4), together with a significant increase in the composition of ergostenol. Exposure to heavy metal ions led to an increase in oleate (with all three metals) and altered relative proportions of linoleate and parinate (changes being metal specific). Metal ion treatment also increased a22 desaturation of chondrillasterol. This characteristic lipid signature when S. capricornutum was exposed to heavy metal ions was significantly different from changes associated with other environmental factors. These changes in lipid composition upon heavy metal treatment were also observed during exposure of S. capricornuiwn to lower metal concentrations typically found in polluted environments. Studies of cells immobilised within alginate beads showed that gel confinement significantly affected the biochemistry and physiology of algal cells, with a reduction in growth rate and final cells numbers. Scanning electron microscopy demonstrated that growth was mainly limited to the bead periphery. Immobilisation altered the lipid of composition of cells as a consequence of alterations in membrane fluidity and membrane disruption. The Cu uptake from solution was greater in immobilised cells than free cells, thus gel confinement did not confer any protection to cells. The characteristic and significant changes within the lipid composition of free cells with Cu treatment were similarly observed in immobilised cells but were only apparent at 124 pM Cu. Thus lipid profiles, especially sterol composition of immobilised algal cells, may potentially be utilised as sensitive and novel indicators of heavy metal pollution in freshwater environments.

Despite improved knowledge and advanced treatments of high-grade gliomas, the overall survival rate of glioma patients remains low due to the recurrences and locations of the tumour. Evidence shows that the existence of a subpopulation of cells - cancer stem cells (CSCs) may be the major obstacle in treating gliomas. CD133 and nestin have been suggested as the markers of CSCs and natural stem cells. The primary focus of this study was to identify CD133+/nestin+ stem-like cells and discover their association with multidrug resistance (MDR) related genes, i.e. multiple drug resistance I (mdrl) gene and anti-apoptotic gene (bcl-2) in human glioma compared to normal brain tissues and cell lines. Glioma and normal astrocyte cell lines have been employed for CD133 isolating purposes to characterise the association with MDR related genotype and phenotype. The chemosensitivity of the isolated CD 133 population was investigated using chemosensitivity assay. Meanwhile, a serum deprivation method was established in this study to enrich and select CD 133+ CSCs in a glioma (GOS-3) cell line. As a secondary focus of this project, the possibility of immortalisation enzyme hTERT being a discriminative masker between normal and cancer brain stem cells and the transcriptional correlation between cd133 and bmi-lIc-myc oncogenes were investigated. For the first time, findings of the current study demonstrated that 1) there was an evident increase of CD133 gene expression in glioma compared to normal brain tissues where the latter expressed low levels of CD133, P-gp and Bcl-2 than glioma tissues, with an exception of nestin expression, 2) serum deprivation enriched CD133 expression and demonstrated a direct coexpression between CD133 and drug resistance in GOS-3 cells, 3) hTERT may not be a discriminative marker for normal and cancer brain stem cells, 4) although there was a strong transcriptional association between bmil and cmyc, there was an inverse transcriptional association between these genes and cd133 in serum deprived glioma cells, suggesting that bmil may not be essential for the maintenance of glioma stem cells, and 5) CD133+ glioma and normal brain cells showed a significantly high resistance towards chemotherapeutic drugs compared to the autologous CD133- cells. In conclusion, an improved understanding of molecules contributing to the maintenance of CSCs may lead to a combined treatment, targeting both CSCs and their protective MDR phenotypes leading eventually to attractive strategies for the treatment of gliomas.

In the mammal, anaesthetics are known to act via two distinct mechanisms, either increasing inhibition via GABAA receptors (eg. Na-thiopentone) or decreasing excitation via NIvIDA receptors (eg. ketamine). The aim of this thesis is to investigate the effects of both increased inhibition and decreased excitation at the synaptic level within an invertebrate model system, something which cannot readily be done in vertebrate systems. This was achieved by carrying out experiments using both the above mentioned anaesthetics on the whole animal, isolated brain and cultured neurons. In invertebrates it has been shown that GABA and Glutamate can be both excitatory and inhibitory, and injection of GABA into Lymnaea has been shown to result in behavioural changes in feeding, locomotion, escape reactions, male mating and respiration. Injection of Na-thiopentone into the whole animal was carried out in this investigation, in order to establish the anaesthetic response of the animal model to this barbiturate. The presence of gamma-aminobutyric acid (GABA) receptors has been demonstrated in a respiratory interneuron (RPeD1) both electrophysiologically and via molecular techniques, however inmiunostaining has proved negative in RPeD1 and follower cells VD2/3 (unidirectional excitatory synapse) and VD4 (mutual inhibitory synapse). This suggests that these neurons are not themselves GABAergic, although this investigation shows the responses of these neurons to bath and direct application of GABA. Na-thiopentone did not reliably anaesthetise Lymnaea upon injection into the sole of the foot, suggesting that Na-thiopentone binds to proteins within the snail, andlor has a low affininty for the GABAA receptor in Lymnaea. Other anaesthetic studies using propofol and ketaniine have also demonstrated a lack of anaesthetic response. RPeD1 hyperpolarised and became quiescent in response to the application of high concentrations of GABA (10 3-104M), however at lower doses (1O 8-1O 5M), no effect was observed (p < 0.05). Under these conditions simultaneous recordings from VD4 showed hyperpolarisation in response to the application of GABA, whereas VD2 and VD3 exhibited excitatory responses. Presynaptic picoinjection of GABA also resulted in hyperpolarisation and quiescence in RJeD1, but the simultaneous response in VD3 was not observed. Postsynaptic application of GABA directly to 'VD2, and VD4 however, resulted in responses similar to those seen in the whole brain. VD2 and 3 also receive input 2, which hyperpolarises RPeD1 and elicits an excitatory EPSP in VD2 and 3 as this is similar to the response observed in this experiment it is possible that the effects of input 2 on RPeD1 and VD2 & 3 are mediated by GABA. As RPeDI does not stain positively for GABA and hyperpolarises in response to the drug, it seems unlikely that the postsynaptie effects are due to presynaptic release of GABA. RPeD1 has been shown to form reciprocal synapses with VD4 both in vivo and in vitro. When perfused with GABA (lmJ'i4), both cells hyperpolarised reversibly. The postsynaptic response could be due to the action of GABA presynaptically inhibiting RPeDI, or directly on postsynaptic GABA receptors. However VD4 forms connections with other cells in the brain such as input 3 which may also have resulted in this inhibitory response. RPeD1 would however have received a simultaneous excitatory input from this interneuron. Attempts were made to establish the nature of the RPeD1JVD4 synapse in these experiments, but no synapses were evident. These experiments therefore confirm the presence of GABA receptors in RPeD1 and suggest theft presence in VD2, and VD4. This investigation confirms the findings of previous studies, that injection and bath perfusion of barbiturates does not lead to responses in Lymnaea comparable to that of the mammal. In addition to it's main target site, ketamine (a frequently used intravenous anaesthetic) has also been shown to act at cholinergic receptors. The effects of ketamine on learning and memory and apoptosis in the mammalian CNS are well recognised. Within the Lymnaea CNS, VD4 and LPeD1 form a unidirectional excitatory cholinergic synapse, and this was chosen to investigate the effects of ketamine on excitatory synaptic transmission, short term potentiation and synapse formation in the invertebrate animal model. Ketamine decreased synaptic transmission between VD4 and LPeD1 in a concentration dependent manner, but did not significantly affect short term synaptic plasticity (pc0.05). While neurite outgrowth remained extensive, actual sprouting was diminished by all doses of ketamine. Cells exhibited extensive veiling, which was not present in control cells. Percentage chemical synapse formation was reduced by all doses of ketamine, and in some cases inappropriate inhibitory chemical synapses were formed. Furthermore acute, clinically relevant levels of ketamine reduce excitatory cholinergic transmission between VD4 and LPeD1, but short term plasticity is unaffected. Nerve regeneration was seriously compromised, and formation of appropriate chemical synapses greatly reduced. This data has serious implications for the clinical - use of ketamine, particularly in pregnant women, children or critical care patients where nerve regeneration and synapse formation are of great importance and long term exposure common practice. In conclusion, this work supports that of other studies which have showed that invertebrates appear to be relatively insensitive to barbiturates, whereas ketamine appears to effect excitation in a manner similar to that in the mammal.

Antiulcer agents, notably inhibitors of gastric acid secretion, have been the most successful category of drugs to be discovered in recent years; and moreover, there are currently four such agents in the world list of top 25 best selling drugs. Histamine H2 antagonists have been the number one selling pharmaceutical product for more than a decade and inhibitors of the parietal cell HIC-ATPase, so called "proton pump inhibitors" (PPI), look set to continue this success. The proposed study was designed to establish the relative efficacy and mechanisms of action of three novel agents using both in vitro and in vivo models. The three compounds namely AG-1749 (Lansoprazole), PD-136450 and transforming growth factor alpha (TGF(x) were studied to evaluate their antisecretory and antiulccr activities. Lansoprazole, the second PPI to be developed for clinical use, is a non-competitive inhibitor of the H1C-ATPase and has recently been launched in a number of countries. PD-136450 is a competitive antagonist of central and peripheral cholecystokinin-B (CCK-B) receptors (gastrin receptor) and it under clinical development as an anxiolytic but which has actions on the stomach and pancreas. Anxiolytic drug is otherwise known as anti-anxiety drugs, which are used to treat anxiety disorders, like depression, panic disorders, phobias and many personality disorders. TOFu is a polypeptide growth factor, which acts at the EGF receptor and displays potent mitogenic and antisecretory activity. The initial study deals with the comparison of the three compounds with omeprazole and ranitidine in terms of their ability to inhibit acid secretion and their activity in a range of experimental ulcer models. Potency, duration of action and activity against a range of stimulants of acid secretion (histamine, pentagastrin and basal) was determined in anaesthetized rat models by establishing dose-response relationships. The compounds represent a spectrum of activities in as much as lansoprazole is a potent, long acting inhibitor, PD-136450 is an orally active but selective inhibitor, while TOFu has a very short duration and is only active after parenteral administration. In a view to find out the mechanism of action of these drugs on gastric acid secretion, isolated gastric glands from rabbits were employed as an in vitro technique using radiolabeled 14C-aminopyrine as a marker. The results show that lansoprazole was the most potent antisecretory agent compared to other two drugs. The second phase of the study deals with the activity of the three compounds against gastric ulcers induced by acid hypersecretion, indomethacin and stress. This study enabled us to assess the extent to which antisecretory activity per se compared with other actions such as wound healing (TGFa) or anxiolytic activity (PD-136450) contribute to ulcer healing. As other workers already established that prostaglandins and nitric oxide are involved in the cytoprotective activity, the present study investigated the influence of prostaglandin and nitric oxide by using indomethacin and L-NAME pretreatment on the cytoprotective activity of lansoprazole, PD-136450 and TGFcz. Moreover, the three drugs were tested for their activities on the mucus and bicarbonate production in the stomach. It was found that lansoprazole and TGFc increased the gastric mucus secretion while PD-136450 did not show any change. Moreover it was evidenced from this study that the protective activity of PD-136450 is associated with the influence of bicarbonate secretion from the pancreas. In conclusion, the results of this study have indicated that lansoprazole, PD- 136450 and TGFct are potent antisecretory and antiulcer agents which have great therapeutic importance.

Mature skeletal muscle fibres can be classified as type I, type IIa, type IIx or type IIb fibres according to the myosin heavy chain (MHC) isoform that they express. More broadly, type I fibres are classified as slow fibres and type IIa, IIx and IIb fibres as fast fibres. However, the phenotype of an adult skeletal muscle fibre is not fixed: it displays plasticity being capable of adapting to changing activity and loading levels by either transition towards a slower phenotype or transition towards a faster phenotype. Overall, the aims of these studies were to further investigate and define the signal transduction pathways implicated in the control of skeletal muscle fibre phenotype. The ability of a fast muscle to undergo a transition towards a slower phenotype in response to chronic low-frequency stimulation (CLFS) was assessed, via metabolic enzyme activity assays and NADH-TR staining, following blockade of the calcineurin signalling pathway. Metabolic enzyme assays and northern blots were employed to assess the changes in enzyme activities and MEC isoform expression levels following blockade of the calcineurin and ERK1/2 signalling pathways in primary cultures of rat myotubes. Differences in the levels of various signal transduction proteins/transcription factors between slow and fast muscle were investigated using western blotting. The nuclear translocation kinetics of NFAT and NF-κB in response to treatment with the calcium ionophore A23187 were investigated in L6 myotubes using immunocytochernistry. Calcineurin blockade using cyclosporin A failed to prevent a decrease in lactate dehydrogenase activity and an increase in NADH-TR staining intensity, both characteristics of a transition towards a slower phenotype, following CLFS of the fast rat tibialis anterior muscle. Blockade of the ERK1/2 pathway in primary cultures of rat myotubes using U0126 significantly decreased MHC Iβ mRNA levels and significantly increased MIHC IIx, MEC IIb and perinatal MHC mRNA levels. Calcineurin blockade significantly decreased MHC Iβ and embryonal mRNA levels and significantly increased MHC IIx mRNA levels. Calcineurin blockade also significantly increased the activities of lactate dehydrogenase and creatine kinase while ERK1/2 blockade significantly increased the activities of lactate dehydrogenase, creatine kinase, hexokinase, malate dehydrogenase and β-hydroxyacyl-CoA deydrogenase. ERK1/2 and NF-κB levels were found to be higher in slow muscle compared to fast muscle while calcineurin and p38α,β levels were higher in fast muscle compared to slow muscle. No nuclear translocation of NF-κB and only limited evidence for NFAT nuclear translocation was seen in L6 myotubes following treatment with A23187. Overall these studies further characterize the roles of the ERK1/2 and calcineurin pathways in the regulation of muscle phenotype suggesting that each pathway controls some, but not all, of the genes that are differentially expressed between slow and fast muscle fibres. Western blotting suggests further signal transduction protein/transcription factor targets, the functions of which may be explored in the future.

Research has consistently demonstrated that exposure to nature, as opposed to urban environments, can be beneficial to health and wellbeing. Among natural landscapes, aquatic (blue space) scenes are among the most preferred and psychologically restorative. Since such landscapes face an increasing range of demands, there is a need to understand how their restorative qualities arise and might be preserved, both in terms of the content of a scene and the psychological processes involved in its interpretation. This thesis examines the cognitive impact of placing artificial (human-made) objects in natural landscapes with and without water. It reports new findings regarding the importance of specific scene content for the restorative potential of blue space. The research also explores some of the underlying psychological processes, addressing novel questions about implicit (subconscious) attitudes towards natural landscapes. It compares implicit and explicit attitudes for the first time in this context. In four studies, methods from social and experimental psychology were used to investigate attitudes towards blue and green space with and without artificial objects. To examine the issues of both artificial objects and implicit attitudes, Study 1 used the Affect Misattribution Procedure (which measures implicit attitudes towards images) to assess whether implicit affect (subconscious positive or negative emotion) differed when the same natural scene was viewed with and without artificial objects. Results showed that introducing objects into natural scenes had a negative impact on implicit affect, particularly when the scene contained water. In order to be able to compare implicit and explicit attitudes, Study 2 examined explicit affective reactions to the images from Study 1 using questions adapted from the Perceived Restorativeness Scale (a measure of the restorative potential of environments). Blue space scenes were rated more highly than green space scenes on all components except aesthetics. The presence of artificial objects resulted in lower ratings on all measures for both blue and green scenes. Study 3 was motivated by an indication in the results from Study 1 that implicit attitudes towards blue and green space may differ. The Affect Misattribution Procedure was used to investigate this for natural landscapes without artificial objects. The study also examined whether implicit attitudes differ according to the type of blue or green environment. Viewing blue space scenes resulted in more positive implicit affect than green space, with sea views generating the most positive implicit affect of all. Following the discovery that artificial objects had a more negative impact on implicit attitudes to blue space than green space, Study 4 tested the possibility that this could be due to such objects being more disruptive to the conceptual coherence of aquatic scenes. The conceptual-semantic congruence of artificial objects was assessed using a lexical decision task, in which participants reacted to object words superimposed on scenes. Results did not support the hypothesis that artificial objects are less congruent in blue space than green space. Overall, the studies provide evidence that placing artificial objects in natural landscapes, particularly aquatic landscapes, adversely affects both implicit and explicit attitudes towards the scenes and may reduce their restorative potential. By successfully combining methods from social and experimental psychology, this research validates novel ways of formulating and addressing questions about why some environments have a more positive psychological impact than others. The new results reported here are not easily explained by current restorative theory, therefore might contribute to refining the theoretical framework within which restorative environments are studied.

Rapid growth of energy consumption and greenhouse gas emissions from fossil fuels have promoted extensive research on biofuels. Algal biofuels have been considered as a promising and environmentally friendly renewable energy source. However, several limitations have inhibited the development of cost-effective biofuel production, which includes unstable cultivation caused by invading organisms and high cost of lipid extraction. This dissertation aims to investigate photochemical approaches to prevent culture collapse caused by invading organisms and biological approaches for the development of cost-effective lipid extraction methods.

As a chemical-free water treatment technology, ultraviolet (UV) irradiation has been widely applied to inactivate pathogens but has not been used in algal cultivation to control invading organisms. To evaluate the potential of using UV irradiation to control invading algal species and minimize virus predation, Tetraselmis sp. and Paramecium bursaria Chlorella virus 1 (PBCV-1) were examined as challenge organisms to evaluate effectiveness of UV disinfection. The concentration of viable (reproductively/infectively active) cells and viruses were quantified by a most probable number (MPN) assay and a plaque assay. A low-pressure collimated-beam reactor was used to investigate UV₂₅₄ dose-response behavior of both challenge organisms. A medium-pressure collimated-beam reactor equipped with a series of narrow bandpass optical filters was used to investigate the action spectra of both challenge organisms. Both challenge organisms showed roughly five log₁₀ units of inactivation for UV₂₅₄ doses over 120 mJ/cm². the most effective wavelengths for inactivation of Tetraselmis were from 254 nm to 280 nm, in which the inactivation was mainly attributed to UV-induced DNA damage. On the contrary, the most effective wavelength for inactivation of PBCV-1 was observed at 214 nm, where the loss of infectivity was mainly attributed to protein damage. These results provide important information for design of UV reactors to minimize the impact of invading organisms in algal cultivation systems.

Additionally, a virus-assisted cell disruption method was developed for cost-effective lipid extraction from algal biomass. Detailed mechanistic studies were conducted to evaluate infection behavior of Chlorovirus PBCV-1 on Chlorella sp., impact of infection on mechanical strength of algal cell wall, lipid yield, and lipid distribution. Viral disruption with multiplicity of infection (MOI) of 10^-8 completely disrupted concentrated algal biomass in six days. Viral disruption significantly reduced the mechanical strength of algal cells for lipid extraction. Lipid yield with viral disruption increased more than three times compared with no disruption control and was similar to that of ultrasonic disruption. Moreover, lipid composition analysis showed that the quality of extracted lipids was not affected by viral infection. The results showed that viral infection is a cost-effective process for lipid extraction from algal cells as extensive energy input and chemicals required by existing disruption methods are no longer needed.

Overall, this dissertation provides innovative approaches for the development of cost-efficient algal biofuels. Application of UV disinfection and viral disruption significantly reduces chemical consumption and improves sustainability of algal biofuel production.

The goal of my dissertation is to take a step toward shifting the narrative in engineering from “surviving” to “thriving” so that more engineering students can reach their full potential in college and beyond. Many engineering students experience barriers such as the hardships of engineering culture, which are exacerbated for women and underrepresented racial/ethnic minorities(such as Black, Latinx, and Indigenous students). These barriers are well documented in research and well discussed in interventions to support engineering student success, under the assumption that helping students cope with these cultural and systemic barriers will, by itself, lead to their success. My research on engineering thriving challenges this assumption by asserting that the skills engineering students need to succeed academically, socially, and personally differ from the skills they need to “survive” cultural and systemic barriers.