bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Construction of the Anechoic Chamber at Queen Mary College
Authors: Ellison A. J. , Miller B. B.
Published: December 2015

A number of anechoic chambers are at present being built, or are projected, in various parts of Great Britain. The present paper, after briefly discussing the basic principles of anechoic-chamber design, sketches the background to the recently completed chamber at Queen Mary College. A fairly detailed description of the design and construction of the chamber is then given, followed by details and results of its commissioning.

Emphasis is laid on the mechanical construction.
Instruction in Internal Combustion Engines
Authors: Davies S. J.
Published: December 2015

Internal combustion engines, forming part of a degree or similar course in thermodynamics, are treated in the order: ideal cycles, cycles using actual working substances in ideal engines, consideration in detail of spark-ignition and compression-ignition engines, petrol and oil engines being taken as the representative types. The progressive or historical development of the subject is emphasized and considerable reference is made to laboratory work. Lastly, comments are offered on post-graduate work.

For the petrol engine, the combustion processes are studied at length, based on the work of Ricardo, Tizard, and Pye, which led to an understanding of detonation and to the octane number as a criterion of fuel quality. For the compression-ignition engine, the combustion processes are similarly studied, the basic work of Le Mesurier and Stansfield and of Boerlage and Broeze, leading to the cetane number, receiving particular attention. Several kinds of comparison are drawn between the characteristics of spark-ignition and compression-ignition engines. For both types of engine, the combustion processes are considered in relation to the performance of engines in the laboratory.

The selection of material in view of the restricted time of the course is touched upon. In appendixes will be found recommended laboratory equipment and suggested works of reference of value to an instructor.
Wire Rope Transmission Losses
Authors: Hind E. C.
Published: December 2015

Transmission losses are determined for 20 wire ropes commonly used in crane and hoist practice. The apparatus and procedure used in determining the losses are described and the results are presented in the form of graphs. From these graphs the law governing the losses is established. The results of work done in Germany and Italy are used to show that the law holds for a large variety of rope types. These results allow conclusions to be drawn from tests on 81 ropes leading to the more specific form of the law. The losses are characterized by transmission loss coefficient K which is found to depend on type of rope construction, lay and finish. Values of K are given in Appendix I for a large variety of rope types.

The mean values of K are given for all bright steel ropes, for galvanized ropes, Lang lay ropes and for one-operation parallel laid ropes.

Using the mean value of K for all ropes a simplified form of the law is obtained. This simplified form will yield results which will probably be within 20 per cent of the actual losses for any type of rope.
Research into the Design of Grabs by Tests on Models
Authors: Wilkinson H. N.
Published: December 2015

Various lines of research into grab design have been tried since investigations started in 1953. It was finally decided to concentrate on the technique of using models. Laboratory apparatus was constructed consisting of one-twelfth scale clamshell and wide-span grabs which could be made to dig into suitably sized samples of iron ore, the ‘pick-up’ being measured and recorded.

The main conclusions are that existing grabs are proportioned in about the best way possible, and that extra weight increases the efficiency only with very lumpy materials, where the efficiency is, in any case, low. Also, weight for weight, the wide-span grab is more efficient than the clamshell.

Following analytical treatment of the grab mechanisms, results of further tests with model grabs suggest that for maximum pick-up the jaws should exert as high a torque as possible, especially towards the end of the grabbing cycle.
Oxides of Nitrogen in Diesel Engine Exhaust Gas: Their Formation and Control
Authors: McConnell G.
Published: December 2015

Interest in the emission of oxides of nitrogen in diesel engine exhaust gas stems largely from the air pollution problem which arises when diesel engines are operated in confined spaces. The author describes tests which have been carried out at the B.P. Research Centre, when oxides of nitrogen concentrations were measured on three engine types over a range of operating conditions. Based on the results of these tests, a theory is presented for the formation of nitrogen oxides in the engine cylinder, and general principles are laid down for their control.

The author concludes with recommendations concerning choice of engine type and operating conditions to ensure a minimum discharge of nitrogen oxides.
Dynamic Behaviour of Spur Gears
Authors: Gregory R. W. , Harris S. L. , Munro R. G.
Published: December 2015

In an earlier paper by one of the authors (9) a theoretical analysis suggested that, at certain speeds, large vibrations can occur in a pair of spur gears, without any manufacturing errors and without any external excitation, provided the damping is less than about 0·07 of critical. In this paper a summary is given of an extension to this theoretical analysis, but the main part is concerned with experimental observations on a back-to-back gear test rig. From these observations the maximum dynamic loads on the teeth have been deduced. It has been found that for all applied loads between zero and 1 1/4 times design load, the maximum dynamic load never exceeds twice the design load (the design load is the load which gives a constant transmission error at low speed). It should be noted that if the design load (for which the profile modification is specified) is appreciably greater than the applied load, the dynamic increment may be very large. Excessive profile modification should therefore be avoided. As the damping in the rig is only about 0·02 of critical, these figures are likely to be an upper limit for isolated, precision spur gears.
Influence of Intake Pressure and Temperature upon the Air Consumption of High-Speed Four-Stroke Compression-Ignition Engines, with Particular Reference to Supercharged Engines
Authors: Dicksee C. B.
Published: December 2015

In a previous paper the author showed that in the case of a particular high-speed compression-ignition engine the weight of air received varied directly with the absolute pressure and the three-fourths power of the absolute temperature of the air at the engine intake. Information obtained later from a number of engines of differing size and design showed that the three-fourths power held good in every case. From this it is concluded that the three-fourths power has general application to the high-speed compression-ignition engine.

On application of this factor to the supercharged engine it has been found to hold good here also. In this case, however, it is necessary to take into account the additional weight of air received by reason of the pressure in the clearance volume being raised to that at the engine intake. A factor for taking this into account is given for a range of compression ratios and intake conditions together with a method for calculating the air consumption under any given set of intake conditions.

In the case of a supercharged engine provided with a wide valve overlap the quantity of air which passes directly to the exhaust during the overlap period may be determined by calculating the quantity of air that will be retained within the cylinder for the prevailing conditions and subtracting this from the measured air consumption.
Events Leading to Erosion in the Steam Turbine
Authors: Gardner G. C.
Published: December 2015

A simple history is ascribed to the liquid water in. the low-pressure stages of the steam turbine which accounts, in a semi-quantitative manner, for many of the observed facts concerning erosion of moving blades. It is shown that supersaturation causes precipitation of fine water drops away from surfaces and that probably only a small number of these drops are collected by blading through impact and diffusional processes. Erosion is believed to be caused by comparatively large drops torn from the blades and by water which has been centrifuged to and is travelling along the casing.

Calculations are given which illustrate the acceleration of water drops in steam, for it is supposed that the normal component of the impact velocity causes erosion damage. Thus drops travelling at the steam velocity are relatively harmless. Calculation also shows that the normal velocity component will decrease towards the tip of long blades, which may be valuable in mitigating erosion. Finally, calculation indicates that most of the water flowing over the surface of moving blades is discharged from the tips, a factor of considerable importance in explaining the simpler aspects of the erosion pattern.
South African adolescents’ beliefs about depression
Authors: Aggarwal Shilpa , Berk Michael , Taljard Lian , Wilson Zane
Published: December 2015

Purpose:

This study explores the depression literacy in adolescents in South Africa.

Method:

A semi-structured questionnaire was administered to 2,050 students from disadvantaged secondary schools in Johannesburg region.

Result:

A total of 90.9% reported depression as an illness, and 41.4% considered it a sign of weakness. Parents and siblings followed by friends and teachers were the preferred support options. The indicators of depression identified were socialisation pattern changes (24.6%), sad mood (23.6%), sleeping and eating pattern changes (18.3%), irritable behaviour (12.5%) and other health risk behaviours (9.7%).

Conclusion:

The majority considered depression an illness. An improvement in adolescent mental health literacy will increase access to help when needed.
Examining Anxiety and Depression Comorbidity Among Chinese and European Canadian University Students
Authors: Chia Ai-Lan , Graves Roger
Published: December 2015

Clark and Watson’s tripartite model of comorbidity between anxiety and depression has been well-supported by empirical evidence among European descent samples in North America. Its applicability to Chinese biculturals remains to be challenged due to two Chinese-specific symptom reporting style in somatization and under-endorsement of positive affect. The current study began with an evaluation of a revised Clark and Watson’s tripartite model of comorbidity by adopting a comprehensive assessment of anxiety- and depression-specific component, and by incorporating cognitive aspects of symptomatology. The revised model’s applicability to a Chinese Canadian university sample was then empirically tested, followed by an investigation of the potential impact of cultural experiences on symptomatology. Item response theory (IRT)–informed statistical analyses were applied to each of the 14 anxiety and depression symptom measures that 251 European Canadian and 206 Chinese Canadian university student participants completed to remove items that functioned differentially across samples. Sample-specific exploratory factor analyses identified a two-factor structure (Affective-Somatic and Cognitive) among the Chinese Canadian sample, and a three-factor structure (Mixed, Cognitive, and Autonomic Hyperarousal) among the European Canadian sample. Worry and Autonomic Hyperarousal scales reflected the most between-group structural differences. These results indicated that different cultural groups responded differently to clinical assessment items commonly used in North America, and that applicability of the tripartite model of comorbidity across cultural groups was limited. Symptom factors were found related to specific (i.e., negative acculturative experiences and collective self-esteem) but not to generic indicators of acculturation (i.e., Chinese or Canadian Orientation).
A Multiple Goals Analysis of Families Attempting to Encourage U.S. Service Members to Seek Behavioral Health Care: Linking the GPA Model and Confirmation Theory
Authors: Wilson Steven R. , Hall Elizabeth Dorrance , Gettings Patricia E. , Pastor Rebekah G.
Published: December 2015

Drawing on the goals-plans-action (GPA) model and confirmation theory, this study explores associations between family members’ primary and secondary goals, planning (i.e., subgoals related to accomplishing the primary goal), and messages encouraging military service members (SMs) to seek behavioral health care. Family members ( N = 244) of SMs who had been deployed to Iraq or Afghanistan described what they would say in a scenario where their SM was displaying mental health symptoms and provided importance ratings for primary and secondary goals as well as subgoals. Based on confirmation theory, messages were coded for levels of acceptance, challenge, and autonomy support. Primary goals predicted multiple dimensions of confirmation, both directly and indirectly through subgoals, but the direction of these effects often ran contrary to one another. Secondary goals also predicted confirmation after controlling for primary goal importance. Implications for the GPA model, confirmation theory, and programs that support military families are discussed.
‘An intensity around information’: the changing face of chemical information literacy
Authors: Bawden David , Robinson Lyn
Published: December 2015

The changing nature of chemical information literacy over 50 years is examined by a comparison of a number of guides to chemical literature and information. It is concluded that: an understanding of the world of information is the sole aspect to have remained important and essentially unchanged over time; that knowledge of sources, ability to access information and ability to organize information have been of importance throughout, but have changed their nature dramatically; and that evaluation of information has gained in importance since the advent of the World Wide Web. The link between chemical structure and corresponding substance information is the most significant threshold concept. Information literacy in chemistry is strongly subject-specific.
Nitric oxide inhalation reduces brain damage, prevents mortality, and improves neurological outcome after subarachnoid hemorrhage by resolving early pial microvasospasms
Authors: Terpolilli Nicole A , Feiler Sergej , Dienel Ari , Müller Frank , Heumos Nicole , Friedrich Benjamin , Stover John , Thal Serge , Schöller Karsten , Plesnila Nikolaus
Published: December 2015

Subarachnoid hemorrhage is a stroke subtype with particularly bad outcome. Recent findings suggest that constrictions of pial arterioles occurring early after hemorrhage may be responsible for cerebral ischemia and – subsequently – unfavorable outcome after subarachnoid hemorrhage. Since we recently hypothesized that the lack of nitric oxide may cause post-hemorrhagic microvasospasms, our aim was to investigate whether inhaled nitric oxide, a treatment paradigm selectively delivering nitric oxide to ischemic microvessels, is able to dilate post-hemorrhagic microvasospasms; thereby improving outcome after experimental subarachnoid hemorrhage. C57BL/6 mice were subjected to experimental SAH. Three hours after subarachnoid hemorrhage pial artery spasms were quantified by intravital microscopy, then mice received inhaled nitric oxide or vehicle. For induction of large artery spasms mice received an intracisternal injection of autologous blood. Inhaled nitric oxide significantly reduced number and severity of subarachnoid hemorrhage-induced post-hemorrhage microvasospasms while only having limited effect on large artery spasms. This resulted in less brain-edema-formation, less hippocampal neuronal loss, lack of mortality, and significantly improved neurological outcome after subarachnoid hemorrhage. This suggests that spasms of pial arterioles play a major role for the outcome after subarachnoid hemorrhage and that lack of nitric oxide is an important mechanism of post-hemorrhagic microvascular dysfunction. Reversing microvascular dysfunction by inhaled nitric oxide might be a promising treatment strategy for subarachnoid hemorrhage.
Dysfunction of brain pericytes in chronic neuroinflammation
Authors: Persidsky Yuri , Hill Jeremy , Zhang Ming , Dykstra Holly , Winfield Malika , Reichenbach Nancy L , Potula Raghava , Mukherjee Abir , Ramirez Servio H , Rom Slava
Published: December 2015

Brain pericytes are uniquely positioned within the neurovascular unit to provide support to blood brain barrier (BBB) maintenance. Neurologic conditions, such as HIV-1-associated neurocognitive disorder, are associated with BBB compromise due to chronic inflammation. Little is known about pericyte dysfunction during HIV-1 infection. We found decreased expression of pericyte markers in human brains from HIV-1-infected patients (even those on antiretroviral therapy). Using primary human brain pericytes, we assessed expression of pericyte markers (α1-integrin, α-smooth muscle actin, platelet-derived growth factor-B receptor β, CX-43) and found their downregulation after treatment with tumor necrosis factor-α (TNFα) or interleukin-1 β (IL-1β). Pericyte exposure to virus or cytokines resulted in decreased secretion of factors promoting BBB formation (angiopoietin-1, transforming growth factor-β1) and mRNA for basement membrane components. TNFα and IL-1β enhanced expression of adhesion molecules in pericytes paralleling increased monocyte adhesion to pericytes. Monocyte migration across BBB models composed of human brain endothelial cells and pericytes demonstrated a diminished rate in baseline migration compared to constructs composed only of brain endothelial cells. However, exposure to the relevant chemokine, CCL2, enhanced the magnitude of monocyte migration when compared to BBB models composed of brain endothelial cells only. These data suggest an important role of pericytes in BBB regulation in neuroinflammation.
Exploring the use of shape and texture descriptors of positron emission tomography tracer distribution in imaging studies of neurodegenerative disease
Authors: Klyuzhin Ivan S , Gonzalez Marjorie , Shahinfard Elham , Vafai Nasim , Sossi Vesna
Published: December 2015

Positron emission tomography (PET) data related to neurodegeneration are most often quantified using methods based on tracer kinetic modeling. In contrast, here we investigate the ability of geometry and texture-based metrics that are independent of kinetic modeling to convey useful information on disease state. The study was performed using data from Parkinson’s disease subjects imaged with 11C-dihydrotetrabenazine and 11C-raclopride. The pattern of the radiotracer distribution in the striatum was quantified using image-based metrics evaluated over multiple regions of interest that were defined on co-registered PET and MRI images. Regression analysis showed a significant degree of correlation between several investigated metrics and clinical evaluations of the disease ( p < 0.01). The best results were obtained with the first-order moment invariant of the radioactivity concentration values estimated over the full structural extent of the region as defined by MRI ( R2 = 0.94). These results demonstrate that there is clinically relevant quantitative information in the tracer distribution pattern that can be captured using geometric and texture descriptors. Such metrics may provide an alternate and complementary data analysis approach to traditional kinetic modeling.
Dietary fructose aggravates the pathobiology of traumatic brain injury by influencing energy homeostasis and plasticity
Authors: Agrawal Rahul , Noble Emily , Vergnes Laurent , Ying Zhe , Reue Karen , Gomez-Pinilla Fernando
Published: December 2015

Fructose consumption has been on the rise for the last two decades and is starting to be recognized as being responsible for metabolic diseases. Metabolic disorders pose a particular threat for brain conditions characterized by energy dysfunction, such as traumatic brain injury. Traumatic brain injury patients experience sudden abnormalities in the control of brain metabolism and cognitive function, which may worsen the prospect of brain plasticity and function. The mechanisms involved are poorly understood. Here we report that fructose consumption disrupts hippocampal energy homeostasis as evidenced by a decline in functional mitochondria bioenergetics (oxygen consumption rate and cytochrome C oxidase activity) and an aggravation of the effects of traumatic brain injury on molecular systems engaged in cell energy homeostasis (sirtuin 1, peroxisome proliferator-activated receptor gamma coactivator-1alpha) and synaptic plasticity (brain-derived neurotrophic factor, tropomyosin receptor kinase B, cyclic adenosine monophosphate response element binding, synaptophysin signaling). Fructose also worsened the effects of traumatic brain injury on spatial memory, which disruption was associated with a decrease in hippocampal insulin receptor signaling. Additionally, fructose consumption and traumatic brain injury promoted plasma membrane lipid peroxidation, measured by elevated protein and phenotypic expression of 4-hydroxynonenal. These data imply that high fructose consumption exacerbates the pathology of brain trauma by further disrupting energy metabolism and brain plasticity, highlighting the impact of diet on the resilience to neurological disorders.
Acute splenic responses in patients with ischemic stroke and intracerebral hemorrhage
Authors: Vahidy Farhaan S , Parsha Kaushik N , Rahbar Mohammad H , Lee MinJae , Bui Thanh-Tung , Nguyen Claude , Barreto Andrew D , Bambhroliya Arvind B , Sahota Preeti , Yang Bing , Aronowski Jaroslaw , Savitz Sean I
Published: December 2015

Animal models provide evidence of spleen mediated post-stroke activation of the peripheral immune system. Translation of these findings to stroke patients requires estimation of pre-stroke spleen volume along with quantification of its day-to-day variation. We enrolled a cohort of 158 healthy volunteers and measured their spleen volume over the course of five consecutive days. We also enrolled a concurrent cohort of 158 stroke patients, measured initial spleen volume within 24 h of stroke symptom onset followed by daily assessments. Blood samples for cytokine analysis were collected from a subset of patients. Using data from healthy volunteers, we fit longitudinal quantile regression models to construct gender and body surface area based normograms of spleen volume. We quantified day-to-day variation and defined splenic contraction. Based on our criteria, approximately 40% of stroke patients experienced substantial post-stroke reduction in splenic volume. African Americans, older patients, and patients with past history of stroke have significantly higher odds of post-stroke splenic contraction. All measured cytokine levels were elevated in patients with splenic contraction, with significant differences for interferon gamma, interleukin 6, 10, 12, and 13. Our work provides reference standards for further work, validation of pre-clinical findings, and characterization of patients with post-stroke splenic contraction.
Ketogenic diet decreases oxidative stress and improves mitochondrial respiratory complex activity
Authors: Greco Tiffany , Glenn Thomas C , Hovda David A , Prins Mayumi L
Published: December 2015

Cerebral metabolism of ketones after traumatic brain injury (TBI) improves neuropathology and behavior in an age-dependent manner. Neuroprotection is attributed to improved cellular energetics, although other properties contribute to the beneficial effects. Oxidative stress is responsible for mitochondrial dysfunction after TBI. Ketones decrease oxidative stress, increase antioxidants and scavenge free radicals. It is hypothesized that ketogenic diet (KD) will decrease post-TBI oxidative stress and improve mitochondria. Postnatal day 35 (PND35) male rats were given sham or controlled cortical impact (CCI) injury and placed on standard (STD) or KD. Ipsilateral cortex homogenates and mitochondria were assayed for markers of oxidative stress, antioxidant expression and mitochondrial function. Oxidative stress was significantly increased at 6 and 24 h post-injury and attenuated by KD while inducing protein expression of antioxidants, NAD(P)H dehydrogenase quinone 1 (NQO1) and superoxide dismutase (SOD1/2). Complex I activity was inhibited in STD and KD groups at 6 h and normalized by 24 h. KD significantly improved Complex II–III activity that was reduced in STD at 6 h. Activity remained reduced at 24 h in STD and unchanged in KD animals. These results strongly suggest that ketones improve post-TBI cerebral metabolism by providing alternative substrates and through antioxidant properties, preventing oxidative stress-mediated mitochondrial dysfunction.
Hemichannel-mediated release of lactate
Authors: Karagiannis Anastassios , Sylantyev Sergiy , Hadjihambi Anna , Hosford Patrick S , Kasparov Sergey , Gourine Alexander V
Published: December 2015

In the central nervous system lactate contributes to the extracellular pool of readily available energy substrates and may also function as a signaling molecule which mediates communication between glial cells and neurons. Monocarboxylate transporters are believed to provide the main pathway for lactate transport across the membranes. Here we tested the hypothesis that lactate could also be released via opening of pannexin and/or functional connexin hemichannels. In acute slices prepared from the brainstem, hippocampus, hypothalamus and cortex of adult rats, enzymatic amperometric biosensors detected significant tonic lactate release inhibited by compounds, which block pannexin/connexin hemichannels and facilitated by lowering extracellular [Ca2+] or increased PCO2. Enhanced lactate release triggered by hypoxia was reduced by ∼50% by either connexin or monocarboxylate transporter blockers. Stimulation of Schaffer collateral fibers triggered lactate release in CA1 area of the hippocampus, which was facilitated in conditions of low extracellular [Ca2+], markedly reduced by blockade of connexin hemichannels and abolished by lactate dehydrogenase inhibitor oxamate. These results indicate that lactate transport across the membranes may occur via mechanisms other than monocarboxylate transporters. In the central nervous system, hemichannels may function as a conduit of lactate release, and this mechanism is recruited during hypoxia and periods of enhanced neuronal activity.
Hypoxic preconditioning enhances neural stem cell transplantation therapy after intracerebral hemorrhage in mice
Authors: Wakai Takuma , Narasimhan Purnima , Sakata Hiroyuki , Wang Eric , Yoshioka Hideyuki , Kinouchi Hiroyuki , Chan Pak H
Published: December 2015

Previous studies have shown that intraparenchymal transplantation of neural stem cells ameliorates neurological deficits in animals with intracerebral hemorrhage. However, hemoglobin in the host brain environment causes massive grafted cell death and reduces the effectiveness of this approach. Several studies have shown that preconditioning induced by sublethal hypoxia can markedly improve the tolerance of treated subjects to more severe insults. Therefore, we investigated whether hypoxic preconditioning enhances neural stem cell resilience to the hemorrhagic stroke environment and improves therapeutic effects in mice. To assess whether hypoxic preconditioning enhances neural stem cell survival when exposed to hemoglobin, neural stem cells were exposed to 5% hypoxia for 24 hours before exposure to hemoglobin. To study the effectiveness of hypoxic preconditioning on grafted-neural stem cell recovery, neural stem cells subjected to hypoxic preconditioning were grafted into the parenchyma 3 days after intracerebral hemorrhage. Hypoxic preconditioning significantly enhanced viability of the neural stem cells exposed to hemoglobin and increased grafted-cell survival in the intracerebral hemorrhage brain. Hypoxic preconditioning also increased neural stem cell secretion of vascular endothelial growth factor. Finally, transplanted neural stem cells with hypoxic preconditioning exhibited enhanced tissue-protective capability that accelerated behavioral recovery. Our results suggest that hypoxic preconditioning in neural stem cells improves efficacy of stem cell therapy for intracerebral hemorrhage.
The role of the mesolimbic dopamine system in the formation of blood-oxygen-level dependent responses in the medial prefrontal/anterior cingulate cortex during high-frequency stimulation of the rat perforant pathway
Authors: Helbing Cornelia , Brocka Marta , Scherf Thomas , Lippert Michael T , Angenstein Frank
Published: December 2015

Several human functional magnetic resonance imaging studies point to an activation of the mesolimbic dopamine system during reward, addiction and learning. We previously found activation of the mesolimbic system in response to continuous but not to discontinuous perforant pathway stimulation in an experimental model that we now used to investigate the role of dopamine release for the formation of functional magnetic resonance imaging responses. The two stimulation protocols elicited blood-oxygen-level dependent responses in the medial prefrontal/anterior cingulate cortex and nucleus accumbens. Inhibition of dopamine D1/5 receptors abolished the formation of functional magnetic resonance imaging responses in the medial prefrontal/anterior cingulate cortex during continuous but not during discontinuous pulse stimulations, i.e. only when the mesolimbic system was activated. Direct electrical or optogenetic stimulation of the ventral tegmental area caused strong dopamine release but only electrical stimulation triggered significant blood-oxygen level-dependent responses in the medial prefrontal/anterior cingulate cortex and nucleus accumbens. These functional magnetic resonance imaging responses were not affected by the D1/5 receptor antagonist SCH23390 but reduced by the N-methyl-D-aspartate receptor antagonist MK801. Therefore, glutamatergic ventral tegmental area neurons are already sufficient to trigger blood-oxygen-level dependent responses in the medial prefrontal/anterior cingulate cortex and nucleus accumbens. Although dopamine release alone does not affect blood-oxygen-level dependent responses it can act as a switch, permitting the formation of blood-oxygen-level dependent responses.
Drugs of abuse and blood-brain barrier endothelial dysfunction: A focus on the role of oxidative stress
Authors: Sajja Ravi K , Rahman Shafiqur , Cucullo Luca
Published: December 2015

Psychostimulants and nicotine are the most widely abused drugs with a detrimental impact on public health globally. While the long-term neurobehavioral deficits and synaptic perturbations are well documented with chronic use of methamphetamine, cocaine, and nicotine, emerging human and experimental studies also suggest an increasing incidence of neurovascular complications associated with drug abuse. Short- or long-term administration of psychostimulants or nicotine is known to disrupt blood-brain barrier (BBB) integrity/function, thus leading to an increased risk of brain edema and neuroinflammation. Various pathophysiological mechanisms have been proposed to underlie drug abuse-induced BBB dysfunction suggesting a central and unifying role for oxidative stress in BBB endothelium and perivascular cells. This review discusses drug-specific effects of methamphetamine, cocaine, and tobacco smoking on brain microvascular crisis and provides critical assessment of oxidative stress-dependent molecular pathways focal to the global compromise of BBB. Additionally, given the increased risk of human immunodeficiency virus (HIV) encephalitis in drug abusers, we have summarized the synergistic pathological impact of psychostimulants and HIV infection on BBB integrity with an emphasis on unifying role of endothelial oxidative stress. This mechanistic framework would guide further investigations on specific molecular pathways to accelerate therapeutic approaches for the prevention of neurovascular deficits by drugs of abuse.
Measuring the geography of opportunity
Authors: Lens Michael C.
Published: December 2015

Quantitative segregation research focuses almost exclusively on the spatial sorting of demographic groups. This research largely ignores the structural characteristics of neighborhoods – such as crime, job accessibility, and school quality – that likely help determine important household outcomes. This paper summarizes the research on segregation, neighborhood effects, and concentrated disadvantage, and argues that we should pay more attention to neighborhood structural characteristics, and that the data increasingly exist to include measures of spatial segregation and neighborhood opportunity. The paper concludes with a brief empirical justification for the inclusion of data on neighborhood violence and a discussion on policy applications.
Limiting shape of profile due to dual-mode fretting wear in contact with an elastomer
Authors: Mao Xinyu , Liu Wei , Ni Yuanzhi , Popov Valentin L
Published: December 2015

We consider fretting wear due to superimposed normal and tangential oscillations of two contacting bodies, one of which is an elastomer with a linear rheology. Similarly to the contact of elastic bodies, at small oscillation amplitudes, the wear occurs only in a circular slip zone at the border of the contact area and the wear profile tends to a limiting form, in which no further wear occurs. It is shown that under assumption of a constant coefficient of friction at the contact interface, the limiting form of the wear profile does depend neither on the particular wear criterion nor on the rheology of the elastomer and can be calculated analytically in a general form. The general calculation procedure and explicit analytic solutions for two initial forms, parabolic and conical, are presented for various combinations of frequencies and phases of normal and tangential oscillations as well as for various linear rheologies of the elastomer.
Large eddy simulation of turbulent axially rotating pipe and swirling jet flows
Authors: Castro Nicolas D , Demuren Ayodeji O
Published: December 2015

Fully-developed, turbulent rotating pipe flow and swirling jet flow, emitted from the pipe, into open quiescent ambient are investigated numerically using large eddy simulation. Simulations are performed at various rotation rates and Reynolds numbers. Time-averaged large eddy simulation results are compared to experimental and simulation data from previous studies. Pipe flow results show deformation of the turbulent mean axial velocity profile towards the laminar-type Poiseuille profile, with increased rotation. The Reynolds stress anisotropy tensor experiences a component-level redistribution due to pipe rotation. Turbulent energy is transferred from the axial component to the tangential component as rotation is increased. The Reynolds stress anisotropy invariant map also shows a movement away from the one-component limit in the buffer layer, with increased rotation. Exit conditions for the pipe flow simulation are utilized as inlet conditions for the jet flow simulation. Jet flow without swirl and at a swirl rate of S = 0.5 are investigated. Swirl is observed to change the characteristics of the jet flow field, leading to increased jet spread and velocity decay, and a corresponding decrease in the length of the jet potential core. The Reynolds stress anisotropy invariant map shows that the turbulent stress field, with or without rotation straddles the axi-symmetric limit.
Wearing their chains willingly: Athlete burnout and the case of adolescent Gaelic footballers in Ireland
Authors: Hughes Lynette , Hassan David
Published: December 2015

The aim of this article is to challenge the widespread acceptance of player burnout as an athlete’s personal inability to deal with the situational demands of sporting competition. Adapting Coakley’s earlier assertion that burnout is ‘a social problem rooted in the social organization of high performance sport itself’, the interactions between Gaelic athletes and the social world in which they exist are unpacked within an Irish context. Linking findings to Gramsci’s theory of hegemony, ‘dominant power relations’ within the competitive sport setting are identified and critically analysed. It is argued that Gaelic players are exploited within a competitive culture in which they feel entrapped, because their actions are informed by the cultural norms of the Gaelic Athletic Association, the sport’s National Governing Body, and dependent upon relationships with coaches and others in positions of authority in the federation. As such, Gaelic footballers are not voluntary agents, somehow acting independently of the constraints of the complex structures in which they compete. Instead, and aware of the often very intricate interdependencies that exist within the sport, it is argued that player burnout in Gaelic football is best explained through the deployment of a Coakley’s ‘vocabulary of empowerment’.
A personal perspective from the UK: ageing and psychiatrists
Authors: Benbow Susan Mary
Published: December 2015

Objective:

Psychiatrists appointed to National Health Service (NHS) consultant posts in the United Kingdom before a specific date in 1995 qualified for early retirement and this has implications for workforce planning.

Methods:

The author reflects on the implications this has for ageing psychiatrists and for relationships between psychiatrists and patients and families using mental health services, from the perspective of a psychiatrist who took advantage of the opportunity to retire early from a consultant post in the NHS and to develop a new career.

Results:

Older psychiatrists continuing to practise after retirement from consultant roles may bring disadvantages and advantages.

Conclusions:

Older psychiatrists may be a valuable resource for future mental health services, and they may be in a position to try out new ways of working which might be relevant to their younger colleagues in the uncertain future faced by mental health services at a time of austerity.
Man/Computer versus Automatic Scheduling
Authors: Haider S. Wali , Buck James R. , Moodie Colin L.
Published: December 2015

Automatic scheduling was compared with man/computer interactive scheduling for a simulated job shop in experimental sessions. Factors of the job stream were controlled and those factors which contributed to improved man/computer scheduling versus automatic scheduling were identified. Results show that man/computer scheduling generally was superior to automatic scheduling; very significantly in several job stream situations but in one situation the automatic method was best.
Tracking in Two Dimensions as a Function of Dimension Priorities and Tracking Difficulty
Authors: Gopher Daniel , Navon David , Chillag Nela
Published: December 2015

The present paper develops the argument that an effective evaluation of performance under time-sharing conditions requires a joint manipulation of tasks difficulty and operator's resources allocation. An experiment is presented in which each of the dimensions in a two dimensional pursuit tracking task was manipulated and controlled seperately. Single and dual task conditions were created by presenting one dimension or two dimensions simultaneously. Time-sharing efficiency was assessed under a joint manipulation of tracking difficulty on each dimension and their relative priorities. Subjects' tracking ability was individually calibrated by adaptive procedures. Regression equations and performance functions were obtained to describe the joint effects of the experimental variables. Results are discussed in terms of their implications to the problem of measuring capacity, and their contribution to the understanding of tracking behavior.
Assessment of Reduction in Job Heaviness in a Printing Department through Automation
Authors: Lucas Richard L.
Published: December 2015

Initial concerns of management for the level of work required in a printing department spurred the initiation of a work physiology study to assess the heaviness of this work. Resulting figures showed a slight excess in demands made by the job over the capacities of the employees assigned to this department. Anticipating several weeks of even heavier work on special orders, the company purchased a new delivery system for two presses for use during the upcoming heavy job. Additional job cost studies were made during the special order run with the new equipment in operation. It was found that the difficult operation required substantially less effort and manpower than would have been needed without the new device in operation.
Facial Recognition: Effects of Changing Accessories
Authors: Laughery Kenneth R. , Fowler Richard H.
Published: December 2015

A facial recongition study examined effects of accessories changes between initial exposure to a target person and that person's appearance in a recognition task. Three accessories were manipulated; glasses and beards (present or absent) and hair style (long or short). Changes in both directions had marked negative effects upon recognition, with hit rates dropping as much as 42 percent. The various accessories had differential effects; glasses producing the smallest decrement and beards the largest. False positive errors were also increased by accessory changes. The results have implications for criminal identification systems.
Testing Influences on Human Understanding of Software
Authors: Sheppard S. B. , Love L. T.
Published: December 2015

Eight experienced programmers were each given three FORTRAN programs to memorize and reproduce functionally, without notes. Three levels of complexity of control flow and three levels of mnemonic variable names were independently manipulated. The experimental design was an incomplete split-plot factorial where each programmer was given one version of each program and all levels of the two primary independent variables.

The participants correctly recalled significantly more statements when the complexity of control flow was reduced. Differences in recall for the three levels of mnemonic variable names were not significant.

A further analysis compared the percent of statements correctly recalled to Halstead's E, a measure of the effort required to code a program. The Pearson correlation coefficient was −0.81, over the 24 data points; thus indicating that Halstead's E is a powerful predictor of one's ability to understand a computer program.
Biorhythms: Fact and Fancy
Authors: Wright M. Lattimer
Published: December 2015

Biological rhythms in physical, emotional and intellectual states in humans are discussed. Both popular and scientific views of biorhythms are given and compared. The popular view is found to be inconsistent with scientifically-collected data. Data on real biological cycles and examples of individual biorhythms are given. The significance of accepting and using biorhythmic phenomena is briefly discussed.
Motion Sickness Incidence Induced by Complex Periodic Waveforms
Authors: Guignard J C , McCauley Michael E
Published: December 2015

Independent groups of male college student volunteers were exposed in a standard seated posture to one of 5 conditions of vertical (Z-axis) harmonic oscillation for two hours or until vomiting. A control condition, sinusoidal motion at 0.17 Hz with a root mean square acceleration of 0.13 g, served as the basis of comparison with the remaining four conditions, which were generated by the sum of two sinusoids, namely, the fundamental at 0.17 Hz plus the second (0.33 Hz) or third (0.50 Hz) harmonic. The experimental conditions differed either in the phase relationship or the relative acceleration level of the added harmonic. The predicted motion sickness incidence (MSI) was calculated for each sinusoid alone from a previously derived mathematical model and compared with the obtained MSIs. While the overall differences may have been due to chance, certain motion combinations provoked unexpectedly high MSI. No simple relationship between predicted MSI for single-frequency motion and the obtained complex-motion MSIs emerged from this study. Until further data are forthcoming, guidelines for motion sickness prevention based on the presumption of independence of action of component frequencies in a complex motion must be interpreted with caution.
Enhancement of Radar Imagery by Maximum Entropy Processing
Authors: Mancill Clanton E.
Published: December 2015

The maximum entropy spectrum (MES), a sampled data power spectrum estimator, is applied to the enhancement of imagery obtained by synthetic array radar (SAR) imaging systems. MES offers better frequency resolution than conventional Fourier transform methods for certain signal classes. Since azimuth ground resolution in SAR systems is obtained by doppler frequency measurement of the radar return, the method is capable of enhancing the resolution of SAR maps. The principal signal requirement is adequate signal-to-noise ratio. The maximum entropy method has been tested using data obtained by the Hughes FLAMR radar system. The super-resolution capabilities of the method are demonstrated using FLAMR images of corner reflector arrays.
The Event Related Cortical Potential as an Index of Task Workload
Authors: Wickens Christopher D. , Isreal Jack , Donchin Emanuel
Published: December 2015

This paper describes an investigation which assessed the feasibility of the event related brain potential (ERP) to provide an index of operator workload in adaptive man-machine systems. The characteristics and requirements of such systems are described and some limitations of secondary task workload measures enumerated. The results of an experiment are then presented in which ERPs were recorded from 10 subjects, while the difficulty of a concurrent tracking task was varied. Subjects performed either a one or a two dimensional compensatory tracking task, while ERP's were elicited by presenting discrete auditory stimuli. The amplitude of the P300 complex, a component of the ERP, elicited by the stimuli, decreased from the control condition (no tracking) to the tracking conditions. An ERP based measure of sequential processing of the stimuli was further affected as tracking difficulty was increased from 1 to 2 dimensions. An algorithm for obtaining an on-line ERP based measure of workload is then described.
Human Factors in Designing a Hand-Held Control Unit for a Single-Sideband CB Radio
Authors: Burnette James T.
Published: December 2015

Designing a hand-held control unit for a single-sideband citizens-band (CB) radio involved combining several research techniques and involved specialists from the areas of human factors, marketing, industrial design, and engineering. Task analysis and operational sequence studies were conducted, and expert and informed opinions were gathered from many people during the initial stage of the research. These were followed by a driving simulation to compare a hand-held control unit with a more conventional CB radio in terms of safety and to answer some basic questions about case and keyboard configurations. Four surveys were conducted during various stages of the control unit's development to collect consumer opinions on all aspects of the product. The entire research effort of approximately 4 months involved only one or two human factors specialists to provide the needed information in a timely manner.
Refinement of a Computer Simulation Model for Evaluating DAIS Display Concepts
Authors: Kuperman Gilbert G. , Hann Reuben L. , Berisford Kathleen Mazzella
Published: December 2015

Previously reported application of Systems Analysis of Integrated Networks of Tasks (SAINT) to the Digital Avionics Information System (DAIS) was refined against extensive empirical data produced in man-in-the-loop experiments. The current work demonstrates the process of abstracting task characteristics from human performance data. Emphasis is shown to be required in the areas of the organization of the data, task representation, and threshold levels. Four specific experimental conditions, representative of a dual-task study, are reported along with the corresponding SAINT simulation performance predictions.