دانلود گزارش کارورزی و کار آموزی

 

 

چکیده :

The most important and effective measures against disease outbreaks in the absence of valid medicines orvaccine are quarantine and isolation strategies. In this paper optimal control theory is applied to a systemof ordinary differential equation describing a two-strain avian influenza transmission via the Pontrya-gin’s Maximum Principle. To this end, a pair of control variables representing the isolation strategies forindividuals with avian and mutant strains were incorporated into the transmission model. The infectionaverted ratio (IAR) and the incremental cost-effectiveness ratio (ICER) were calculated to investigate thecost-effectiveness of all possible combinations of the control strategies. The simulation results show thatthe implementation of the combination strategy during the epidemic is the most cost-effective strategyfor avian influenza transmission. This is followed by the control strategy involving isolation of individualswith the mutant strain. Also observed was the fact that low mutating and more virulent virus results inan increased control effort of isolating individuals with the avian strain; and high mutating with morevirulent virus results in increased efforts in isolating individuals with the mutant strain

 

چکیده : 

Myosins are typical molecular motor proteins, which convert the chemical energy of ATP into mechanicalwork. The fundamental mechanism of this energy conversion is still unknown. To explain the experimen-tal results observed in molecular motors, Masuda has proposed a theory called the “Driven by Detachment(DbD)” mechanism for the working principle of myosins. Based on this theory, the energy used during thepower stroke of the myosins originates from the attractive force between a detached myosin head andan actin filament, and does not directly arise from the energy of ATP. According to this theory, every stepin the myosin working process may be reproduced by molecular dynamics (MD) simulations, except forthe ATP hydrolysis step. Therefore, MD simulations were conducted to reproduce the docking process ofa myosin subfragment-1 (S1) against an actin filament. A myosin S1 directed toward the barbed end ofan actin filament was placed at three different positions by shifting it away from the filament axis. After30 ns of MD simulations, in three cases out of ten trials on average, the myosin made a close contact withtwo actin monomers by changing the positions and the orientation of both the myosin and the actin aspredicted in previous studies. Once the docking was achieved, the distance between the myosin and theactin showed smaller fluctuations, indicating that the docking is stable over time. If the docking was notachieved, the myosin moved randomly around the initial position or moved away from the actin fila-ment. MD simulations thus successfully reproduced the docking of a myosin S1 with an actin filament.By extending the similar MD simulations to the other steps of the myosin working process, the validityof the DbD theory may be computationally demonstrated.

 

 

چکیده : 

Controversy persists as to whether the acquisition of beneficial metabolic functions via endosymbiosiscan occur suddenly on an volutionary time scale. In this study, an early stage of endosymbiotic associa-tions, which evolved from previously unassociated auto (photo)- and heterotrophic unicellular organismswas analyzed using an experimental ecosystem model, called CET microcosm. This ecosystem modelwas composed of a green alga (Micractinium sp.; formerly described as Chlorella vulgaris), a bacterium(Escherichia coli), and a ciliate (Tetrahymena thermophila). Our previous study using a CET microcosm thatwas cultured 3–5 years revealed that fitness of the ciliate increased by harboring algal cells within itsown cells. This fact suggested three possibilities: (i) the ciliate evolved the ability to exploit intracellularalgal cells (“exploiter ciliate hypothesis”), (ii) the alga evolved the ability to benefit the host ciliate byproviding photosynthates (“cooperator alga hypothesis”), and (iii) a combination of (i) and (ii). To testthese hypotheses, two-by-two co-cultures were conducted between the ancestral or derived ciliate andthe ancestral or derived alga. The experimental results demonstrated that a cooperative alga evolved inthe microcosm, although the possibility remains that an exploitative genotype of the ciliate might alsoexist in the population as a polymorphism. Remarkably, an algal isolate prolonged the longevity of notonly the isolated ciliate, but also the ancestral ciliate. This result suggests that once a cooperative algalgenotype evolves in a local population, it can then be transmitted to other individuals of the prospectivehost species and spread rapidly beyond the local range due to its positive effect on the host fitness. Suchtransmission suggests the possibility of a sudden acquisition of beneficial autotrophic function by thepre-associated host.

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چکیده : 

Biodiversity is hierarchically structured both phylogenetically and functionally. Phylogenetic hierarchy

is understood as a product of branching organic evolution as described by Darwin. Ecosystem biologists

understand some aspects of functional hierarchy, such as food web architecture, as a product of

evolutionary ecology; but functional hierarchy extends to much lower scales of organization than those

studied by ecologists. We argue that the more general use of the term “evolution” employed by physicists

and applied to non-living systems connects directly to the narrow biological meaning. Physical evolution

is best understood as a thermodynamic phenomenon, and this perspective comfortably includes all of

biological evolution. We suggest four dynamical factors that build on each other in a hierarchical fashion

and set the stage for the Darwinian evolution of biological systems: (1) the entropic erosion of structure;

(2) the construction of dissipative systems; (3) the reproduction of growing systems and (4) the

historical memory accrued to populations of reproductive agents by the acquisition of hereditary mechanisms.

A particular level of evolution can underpin the emergence of higher levels, but evolutionary

processes persist at each level in the hierarchy. We also argue that particular evolutionary processes can

occur at any level of the hierarchy where they are not obstructed by material constraints. This theoretical

framework provides an extensive basis for understanding natural selection as a multilevel process. The

extensive literature on thermodynamics in turn provides an important advantage to this perspective on

the evolution of higher levels of organization, such as the evolution of altruism that can accompany the

emergence of social organization

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چکیده : 

Cognitive-behavioral models of paranoia have emphasized

the potential role of perseverative thinking styles, such as

rumination or worry, in the development, maintenance and

exacerbation of paranoid beliefs. This study aimed to

experimentally test the hypothesis that rumination may play

a role in the maintenance or exacerbation of state paranoid

ideation. Following a paranoia induction, 37 nonclinical

participants were randomly assigned to either a rumination

task or a distraction control condition. In accord with main

hypothesis, rumination was associated with maintained levels

of paranoia, whereas distraction was associated with a

decrease in levels of paranoia. These findings suggest that

perseverative thinking may play a role in the maintenance of

paranoid ideas, which may have implications for our

understanding of the maintenance of paranoia and persecutory

delusions in the clinical population. Furthermore, the

study used a novel experimental paradigm for inducing

paranoia, which may prove valuable for future research

aiming to elicit paranoid thoughts and feelings in vivo.

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چکیده : 

Mindfulness has been associated with anxiety and depression,

but the ways in which specific facets of mindfulness relate to

symptoms of anxiety and depression remains unclear. The

purpose of the current study was to investigate associations

between specific facets of mindfulness (e.g., observing, describing,

nonjudging, acting with awareness, and nonreactivity) and

dimensions of anxiety and depression symptoms (e.g., anxious

arousal, general distress-anxiety, general distress-depression,

and anhedonic depression) while controlling for shared

variance among variables. Participants were 187 treatmentseeking

adults.Mindfulness was measured using the Five Facet

Mindfulness Questionnaire and symptoms of depression and

anxiety were measured using theMood and Anxiety Symptom

Questionnaire. Bivariate correlations showed that all facets of

mindfulness were significantly related to all dimensions of

anxiety and depression, with two exceptions: describing

was unrelated to general distress-anxiety, and observing

was unrelated to all symptom clusters. Path analysis was

used to simultaneously examine associations between

mindfulness facets and depression and anxiety symptoms.

Significant and marginally significant pathways were

retained to construct a more parsimonious model and

model fit indices were examined. The parsimonious model

indicated that nonreactivity was significantly inversely

associated with general distress anxiety symptoms.Describing

was significantly inversely associated with anxious arousal,

while observing was significantly positively associated with it.

Nonjudging and nonreactivity were significantly inversely

related to general distress-depression and anhedonic depression

symptomatology. Acting with awareness was not

significantly associated with any dimensions of anxiety or

depression. Findings support associations between specific

facets of mindfulness and dimensions of anxiety and

depression and highlight the potential utility of targeting

these specific aspects of mindfulness in interventions for

anxiety and mood disorders.

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چکیده : 

Despite negative outcomes for depressed mothers and their

children, no treatment specifically designed to address

maternal depression in the context of home visitation has

emerged. In-Home Cognitive Behavioral Therapy (IH-CBT)

is an adapted treatment that is delivered in the home, focuses

on the needs of new mothers, and leverages ongoing home

visiting to optimize engagement and outcomes. This study

examined the efficacy of IH-CBT using a randomized

clinical trial. Subjects were 93 new mothers in a home visiting

program. Mothers with major depressive disorder identified

at 3 months postpartum were randomized into IH-CBT and

ongoing home visitation () or standard home visitation

(SHV; ) in which they received home visitation alone

and could obtain treatment in the community. Depression

was measured at pre- and posttreatment, and 3-month

follow-up using interviews, clinician ratings, and self-report.

Mothers receiving IH-CBT showed improvements in all

indicators of depression relative to the SHV condition

and these gains were maintained at follow-up. For example,

70.7% of mothers receiving IH-CBT were no longer

depressed at posttreatment in terms of meeting criteria for

major depressive disorder compared to 30.2% in the

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چکیده :

Empirical work has suggested relationships among suiciderelated

outcomes and several constructs related to affect

dysregulation, notably anxiety sensitivity (AS) and distress

tolerance (DT). However, important questions remain,

including the relative contributions of these affect regulation

variables as well as the direct contribution of DT on suicidal

ideation and prior attempts.The current study sought to better

elucidate the nature of these relationships by examining AS,

DT, and suicidal ideation and attempt in a clinical sample

(). Consistent with priorwork and prediction, findings

revealed a significant relationship between the AS cognitive

concerns subfactor and suicidal ideation and suicide attempt

history after accounting for the effects of DT, gender, and

depressive symptoms. In addition, depressive symptoms

significantly moderated the relationship between the AS

cognitive concerns subfactor and suicidal ideation. After

accounting for the influence of AS, analyses revealed that DT

approached significance in predicting suicidal ideation, but

did not significantly predict suicide attempt history. These

results suggest that elevated AS cognitive concerns are

particularly relevant to suicide in the context of depressive

symptoms. Clinicians may benefit from implementing AS

reduction strategies with individuals who endorse elevated

suicide risk as well as elevated AS cognitive concerns.