bluuebunny/crossref_metadata_2025 huggingface dataset:
Persistence of High Fertility in Tropical Africa: The Case of the Democratic Republic of the Congo
Authors: Romaniuk Anatole
Published: March 2011

The article explores how geography, history, and society have shaped childbearing behaviors over the last half‐century, and how they are now being reshaped by modernity and the exigencies of urban life, in the democratic Republic of the congo. the decline of prolonged postpartum abstinence and involuntary childlessness initially raised fertility to high levels (6–7 children per woman). more recently, socioeconomic differentials in fertility have emerged, suggesting that the country may be entering a phase of fertility decline. a full‐blown transition, however, seems still a remote prospect. Supported both by cultural traditions and by economic rationality, congo's people remain largely convinced of the benefts of many children for their own and their kin's security. while an eventual fertility transition may be taken for granted, the article examines the many hurdles, contradictions, and tensions that will have to be overcome to achieve that outcome.
Yearning, Learning, and Conceding: Reasons Men and Women Change Their Childbearing Intentions
Authors: Iacovou Maria , Tavares Lara Patrício
Published: March 2011

People's childbearing intentions change over the course of their reproductive lives. these changes have been conceptualized as occurring in response to the realization that an individual is unlikely to achieve his or her intended fertility, because of constraints such as the “biological clock” or lack of a partner. in this article we fnd that changes to child‐bearing plans are infuenced by a much wider range of factors than this. People change their plans in response to the wishes of their partners, in response to social norms, as the result of repartnering, and as the result of learning about the costs and benefts of parenthood; there are also differences between the factors that infuence men's and women's decisionmaking. in a departure from existing studies in this area, we use a fexible analytical framework that enables us to analyze increases in planned fertility separately from decreases. this allows us to uncover several complexities of the decisionmaking process that would otherwise be hidden, and leads us to conclude that the determinants of increases in planned fertility are not simply equal and opposite to the determinants of decreases.
MAGNETIC RESONANCE IMAGING OF NORMAL AND ABNORMAL BRAIN PERFUSION
Authors: TIDWELL AMY S. , ROBERTSON IAN D.
Published: March 2011

The brain is highly susceptible to injury from any process that deprives its cells of oxygen, glucose, and other essential nutrients, and is therefore critically dependent on blood flow or perfusion. With hypoperfusion or ischemia, blood flow to the brain may be diminished to a level incompatible with normal function, eventually leading to acute ischemic stroke. Magnetic resonance (MR) imaging is one of several imaging methods used to evaluate brain perfusion and stroke. Using a multisequence approach comprised of conventional spin echo, inversion recovery, and heme‐sensitive gradient echo pulse sequences, MR angiography, and diffusion and perfusion sensitive techniques, MR imaging is capable of identifying vascular lesions, measuring abnormal blood flow, and depicting the metabolic and structural consequences of ischemia. MR imaging objectives and strategies for the diagnosis of acute ischemic stroke in humans and animals, terminology, pathophysiology, and normal vascular anatomy are reviewed.
OPTIMAL MAGNETIC RESONANCE IMAGING OF THE SPINE
Authors: DENNIS RUTH
Published: March 2011

Magnetic resonance (MR) imaging is generally considered to be the best imaging modality for the spine because of its excellent tissue contrast and multiplanar imaging capability; however, good technique is vital in order to avoid nondiagnostic or even misleading images. The possibility of imaging in multiple planes and using many different pulse sequences means that judgment is required in order to gain maximum diagnostic information within a reasonable scanning time. Spinal MR imaging technique for small animals is reviewed with emphasis on technical aspects including patient positioning, selection of pulse sequences, and image planes.
IMAGING DOGS WITH SUSPECTED DISC HERNIATION: PROS AND CONS OF MYELOGRAPHY, COMPUTED TOMOGRAPHY, AND MAGNETIC RESONANCE
Authors: ROBERTSON IAN , THRALL DONALD E.
Published: March 2011

Myelography, computed tomography (CT), and magnetic resonance (MR) imaging are the diagnostic modalities currently used in the evaluation of dogs with suspected disc herniation. Where high‐field MR imaging is available, it is considered the optimal modality for any myelopathy in dogs, including those with disc disease. CT myelography may be the next best option, particularly in nonchondrodystrophoid dogs. In chondrodystrophoid dogs, in which extrusion of mineralized disc material is common, plain CT will enable diagnosis in most cases. Myelography is still considered adequate for diagnosis of disc herniation when MR and CT are unavailable.
Insect Herbivory and Leaf Disease in Natural and Human Disturbed Habitats: Lessons from Early‐SuccessionalHeliconiaHerbs
Authors: Santos Bráulio A. , Benítez‐Malvido Julieta
Published: March 2011

The interaction of plants with insect herbivores and fungal pathogens can affect community dynamics, but there is little information on how this antagonistic interaction may be altered in human‐disturbed tropical systems. We examined whether the amount and quality of foliar damage on the pioneer herbsHeliconia latispathaandHeliconia collinsianaare distinct on road edges and secondary riparian vegetation compared with natural gaps in continuous forest (controls) in Mexico. We also investigated some physical and biological mechanisms that may jointly explain such differences. The overall insect damage inH. latispathawas similar between road edges and natural forest gaps (8.0% vs. 7.2% of leaf area). Damage by caterpillars, however, decreased from 4.2 percent in forest gaps to 0.5 percent on road edges, whereas damage by leaf‐cutting ants increased from 0 to 5.8 percent. In secondary riparian vegetation, where none of the leaves sampled were attacked by ants, overall herbivore damage inH. collinsianawas less than half that observed in forest gaps (3.0% vs. 6.7%), and driven mainly by differences in caterpillar damage (2.5% vs. 6.2%). By contrast, attack by leaf fungal pathogens was two to three times greater in both human‐disturbed habitats than in gaps (8.2–9.6% vs. 3.7–4.2%). Potential mechanisms underlying these differences involved human‐induced shifts in air and soil temperature driven by greater light availability, as well as changes in relative humidity, leaf toughness, foliar condensed tannins, and local abundance of herbivores. Our results indicate that human disturbance alters insect herbivory and may increase proliferation of leaf disease.

Abstract in Spanish is available in the online version of this article.
Uremic Toxins and Oral Adsorbents
Authors: Goto Shunsuke , Yoshiya Kunihiko , Kita Tomoyuki , Fujii Hideki , Fukagawa Masafumi
Published: March 2011

Uremic toxins are associated with various disorders in patients with end‐stage renal disease and it is difficult to remove some of these toxins by dialysis. Since some uremic toxins are generated by bacterial metabolites in the colon, oral adsorbents that interfere with the absorption of uremic toxins or their precursors are believed to prevent their accumulation in the body. AST‐120 adsorbs various uremic retention solutes in the gastrointestinal system and has potential for providing clinical benefit. Sevelamer hydrochloride binds some harmful compounds in addition to phosphate and seems to have pleiotropic effects that include lowering serum LDL cholesterol levels and reduction of inflammation. The effect of sevelamer hydrochloride on indoxyl sulfate and p‐cresol has been shown in an in vitro study; however, in vivo studies in mice or humans did not demonstrate this effect on protein‐binding uremic toxins. Oral adsorbents are thus one of the important modalities in the treatment of uremic syndrome.
EVALUATION OF NITROGENOUS COMPOUNDS IN LIGHT PRATO‐TYPE CHEESE WITH WHEAT FIBER, GELATIN AND ADJUNCT CULTURE (LACTOBACILLUS RHAMNOSUS) DURING RIPENING
Authors: VALDUGA EUNICE , RAUBER FERNANDA FÁTIMA , GHISLENI CILDA PICCOLI , TIGGEMANN LÍDIA , COLET ROSICLER , TREICHEL HELEN , CICHOSKI ALEXANDRE JOSÉ
Published: March 2011

The present study aimed to evaluate the effects of the addition of the gelatin, the wheat fiber and the Lactobacillus rhamnosus in the proteolysis of the light Prato‐type cheese during ripening (60 days). The total nitrogen values differed significantly (P < 0.05), with the decrease in casein nitrogen conten and showed a significant increase in amoniacal nitrogen, aminoacid nitrogen, total soluble nitrogen and nonprotein nitrogen (NNP) content, indicating the occurrence of proteolysis. The addition of probiotic culture (L. rhamnosus) in storage for 30 and 60 days over the NNP fraction presented a positive effect in the NNP fraction.

PRACTICAL APPLICATIONS

The industry of functional food has been increasingly exploiting new processes and broadening the diversity of product offerings, in consequence of the increasing interest of consumers towards their health, leading to the search of food that is not only healthy but also capable of preventing disease. The popularity of functional food containing probiotic is increasing in developed countries because of advances in the development of new products, resulting in the incorporation of probiotic to dairy products as well as to beverages, cereals and even to meet products. The literature is scarce in information regarding the employment of gelatin, wheat fiber and probiotic into dairy products, especially cheese.
EXTRACTION OF HYPERFORIN AND HYPERICIN FROM ST. JOHN'S WORT (HYPERICUM PERFORATUM L.) WITH DIFFERENT SOLVENTS
Authors: COSSUTA DÁNIEL , VATAI TÜNDE , BÁTHORI MÁRIA , HOHMANN JUDIT , KEVE TIBOR , SIMÁNDI BÉLA
Published: March 2011

The extraction of St. John's wort (Hypericum perforatum L.) was carried out with different solvents to obtain valuable components and natural agents rich extracts. Further aim of this study was to compare the raw materials that were gathered at the beginning and the end of the blossoming.

For the laboratory Soxhlet extraction of St. John's wort four different solvents (n‐hexane, ethyl acetate, 2‐propanol, ethanol) were applied. Increasing the polarity of solvents higher extraction yields were achieved (43–360 g/kg). Pilot plant experiments were performed in a 5·10
‐

3 m3 volume Soxhlet extractor with ethanol and in a 5·10
‐

3 m3 volume high‐pressure vessel at 313K and 45 MPa with supercritical CO2. The extract samples were analyzed by UV‐visible spectrophotometry and high‐performance liquid chromatography methods.

The effective extraction of both main compounds (hypericin and hyperforin) was achieved. The sample gathered at the end of the blossoming extracted with nonpolar solvent (sc‐CO2) at mild temperature (∼313K) provided stable hyperforin rich extract. The sample gathered at the begining of the blossoming extracted with polar solvent (ethanol) at mild temperature (∼313K) provided stable hypericin rich extract.

PRACTICAL APPLICATIONS

Hypericum perforatum (St. John's wort) is among the favorite herbal drugs, and is the only herbal alternative to classical synthetic antidepressants, in the therapy of mild‐to‐moderate depression. Several studies describe that the active ingredients in St. John's wort are hypericin and hyperforin, which inhibit the reuptake of monoamines, including serotonin, noradrenalin and dopamine, as well as the amino acid neurotransmitters γ‐aminobutiric acid and glutamate. The results from this study can be used for produce a stable hyperforin‐rich extract and a stable hypericin rich extract. These extracts can be utilized for a production of food supplement herbal preparations which standardized on both main compounds.
Valuing amenity: public perceptions of sustainable drainage systems ponds
Authors: Bastien N. R. P. , Arthur S. , McLoughlin M. J.
Published: March 2011

Understanding the potential concerns and needs of residents is key to achieving good acceptability of sustainable drainage systems (SuDS). This paper highlights, through the application of a structured questionnaire, the potential value to residents of living in close proximity to a SuDS pond. The results show that although the pond's characteristics are not the main factor influencing the choice to move into an area, its effect is markedly positive. Contingent valuation of the benefits is used to show that the additional value brought by SuDS amenity, when monetised, can offset a pond's initial construction costs and ongoing maintenance, hence ensuring the return on investment for developers. By building on existing research, this paper highlights major changes in the perception and valuation of pond structures.
What lies ahead for the proprotein convertases?
Authors: Seidah Nabil G.
Published: March 2011

Limited proteolysis of secretory proteins is performed by one or more of the nine‐membered proprotein convertase (PC) family: PC1/3, PC2, furin, PC4, PC5/6, PACE4, PC7, SKI‐1/S1P, and PCSK9. The first seven proteinases cleave proproteins at single or pairs of basic residues in the Golgi, secretory granules, cell surface, or endosomes. These comprise neural and endocrine hormones and their release/inhibiting factors, growth factors and their receptors, and adhesion molecules. The regulated neural and endocrine PC1/3 and PC2 generate multiple peptide hormones and neuropeptides, including the family of hypothalamic‐releasing/inhibiting factors. The ubiquitously expressed furin is the principal PC that processes constitutively secreted proteins. PC4 controls testicular and ovarian physiology. PC5/6 and PACE4 bind heparin sulfate proteoglycans and play critical roles during development by regulating body axis and polarity determinants. PC7 exerts unique functions in the brain. The members SKI‐1/S1P and PCSK9 do not require a basic residue at the cleavage site and play major roles in the regulation of cholesterol/lipid homeostasis. In vivo studies demonstrated that PCs play major roles in health and disease states.
Molecular genetics of hypothalamic–pituitary–adrenal axis activity and function
Authors: Mormede Pierre , Foury Aline , Barat Pascal , Corcuff Jean‐Benoit , Terenina Elena , Marissal‐Arvy Nathalie , Moisan Marie‐Pierre
Published: March 2011

The hypothalamic–pituitary–adrenocortical (HPA) axis is a major neuroendocrine system involved in the regulation of numerous physiological processes and in adaptation to stress. A wide range of variability can be observed in all the components of the system, and the contribution of genetic factors has been shown in the central regulation of the axis, the production of glucocorticoid hormones by the adrenal cortex, their bioavailability, and the efficiency of their action at the level of receptor and postreceptor mechanisms. Numerous molecular polymorphisms have been described that contribute to physiological variation as well as to HPA axis‐related pathological conditions. Although most studies focus on single gene polymorphisms, future studies should aim to integrate the different sources of variation into a systems genetic model to take into account the strong interdependence of the different components of the axis.
From GWAS to biology: lessons from FTO
Authors: Tung Yi‐Chun Loraine , Yeo Giles S. H.
Published: March 2011

Genome‐wide association studies have been very powerful, uncovering potentially new biology that would not have been possible using a candidate gene approach. A prime example of this is the gene FTO (fat mass and obesity associated), which first came to light in 2007, when single nucleotide polymorphisms in its first intron were robustly associated with body mass index and obesity. Subsequently, as it became clear that this association with body weight, and increasingly food intake, was replicable across multiple populations and different age groups, attention was turned to studying the biology of FTO, about which absolutely nothing was known. This review focuses on the genetic and biochemical approaches as well as animal models that have been used by us and others since 2007 to try and uncover the complex biology of FTO.
Adrenal peripheral oscillator in generating the circadian glucocorticoid rhythm
Authors: Chung Sooyoung , Son Gi Hoon , Kim Kyungjin
Published: March 2011

The mammalian circadian timing system is organized into hierarchical structures with a central clock in the suprachiasmatic nucleus (SCN) and subsidiary peripheral oscillators. After the discovery of the local clockwork in peripheral organs and tissues, which have a molecular makeup similar to the central pacemaker SCN, uncovering the roles of the peripheral clock in the rhythmic physiology has been an emerging goal in chronobiology. Glucocorticoid (GC) is a multifunctional adrenal steroid hormone that shows a robust circadian rhythm. The daily GC rhythm has long been thought to be governed by the SCN via the hypothalamus–pituitary–adrenal neuroendocrine axis. Recent findings, however, indicate that multiple regulatory mechanisms, including the adrenal intrinsic mechanism by the peripheral clock, are also involved. GC regulates diverse physiological processes and acts as a signal for resetting peripheral clocks, which suggests the importance of the GC rhythm in harmonizing overall circadian physiology and behavior. Therefore, in this review, we will discuss the important role of the adrenal peripheral clockwork in the circadian regulation of GC and its physiological relevance in the circadian timing system.
C. elegans homologs of insect clock proteins: a tale of many stories
Authors: Temmerman Liesbet , Meelkop Ellen , Janssen Tom , Bogaerts Annelies , Lindemans Marleen , Husson Steven J. , Beets Isabel , Schoofs Liliane
Published: March 2011

As a consequence of the Earth's axial rotation, organisms display daily recurring rhythms in behavior and biochemical properties, such as hormone titers. The neuronal system controlling such changes is best studied in the fruit fly Drosophila melanogaster. In the nematode worm Caenorhabditis elegans, most homologs of these genes function in the heterochronic pathway controlling the (timing of) developmental events. Recent data indicate that in the worm at least one of the genes involved in developmental timing is also active in circadian rhythm control, thereby opening up new perspectives on a central (neuronal) timer interfering with many processes. Also, new neuropeptidergic clock homologs have been identified in nematodes, supporting the idea of a broad range of clock‐regulated targets. We will describe the current knowledge on homologous clock genes in C. elegans with a focus on the recently discovered pigment dispersing factor gene homologs. Similarities between developmental and daily timing are discussed.
Sufficient Vitamin D from Casual Sun Exposure?
Authors: de Gruijl Frank R.
Published: March 2011

Next to the adverse effects of solar UV exposure, the beneficial effects mediated by vitamin D3 have come into the limelight. The question then is “how much sun exposure do we actually need?” Estimates have been made, but the data are not quite adequate. The groups of Drs. Rhodes and Webb bridged the gap between experiments and everyday life by a study in which 109 volunteers were exposed in mid‐winter to simulated solar UV radiation in summertime clothing at dosages of 1.3 SED three times a week. Thus, 90% reached sufficiently high vitamin D statuses (>50 nmol L−1). In this issue, these researchers transpose these experimental exposures in a cabinet to summertime noon exposures of people walking around for about half an hour in open terrain on a clear day in Manchester, UK. This result is an improvement over earlier estimates and shows that casual mid‐day summer sun exposure should indeed suffice.
On the Binding of BODIPY‐GTP by the Photosensory Protein YtvA from the Common Soil Bacterium Bacillus subtilis†
Authors: Nakasone Yusuke , Hellingwerf Klaas J.
Published: March 2011

The YtvA protein, which is one of the proteins that comprises the network carrying out the signal transfer inducing the general stress response in Bacillus subtilis, is composed of an N‐terminal LOV domain (that binds a flavin [FMN]) and a C‐terminal STAS domain. This latter domain shows sequence features typical for a nucleotide (NTP) binding protein. It has been proposed (FEBS Lett., 580 [2006], 3818) that BODIPY‐GTP can be used as a reporter for nucleotide binding to this site and that activation of the LOV domain by blue light is reflected in an alteration of the BODIPY‐GTP fluorescence. Here we confirm that BODIPY‐GTP indeed binds to YtvA, but rather nonspecifically, and not limited to the STAS domain. Blue‐light modulation of fluorescence emission of YtvA‐bound BODIPY‐GTP is observed both in the full‐length YtvA protein and in a truncated protein composed of the LOV‐domain plus the LOV‐STAS linker region (YtvA1–147) as a light‐induced decrease in fluorescence emission. The isolated LOV domain (i.e. without the linker region) does not show such BODIPY‐GTP fluorescence changes. Dialysis experiments have confirmed the blue‐light‐induced release of BODIPY‐GTP from YtvA.
The Democratization of Leisure and the Modernities of Space and Place in Theodor Fontane's Berlin Novels
Authors: Johnson David S.
Published: March 2011

This paper calls for a new reading of Fontane's Berlin novels, one that critically examines how the author's portrayals of such leisure sites as Tiergarten, Stralau, Treptow, Hankels Ablage, and Halensee reflect a democratization of leisure in which all Berliners, regardless of class, have access to a growing number of opportunities for recreation, pleasure, and relaxation. Resulting tensions between these locations as places of comfort and refuge and as urban spaces of crowds, chaos, and modern articulations of consumer society highlight these texts' representations of the dynamic and modern city. As a result, Fontane's Berlin novels reveal a spectrum of experience that is very much intricately tied to the vicissitudes of modern city life. From despair to acceptance and from celebration to mockery, the novels use the experience of leisure at these sites to strike various tones that ultimately capture the ambivalent and unpredictable character of life in the modern metropolis of Berlin.
Fantasies of White Masculinity in Arthur Schnitzler's Andreas Thameyers letzter Brief (1900)
Authors: Boehringer Michael
Published: March 2011

While the notion of masculinity in crisis has become a commonplace in fin‐de‐siècle literary studies, Schnitzler's novella Andreas Thameyers letzter Brief has thus far been investigated primarily with respect to the (pathological) psychology of its protagonist and the contemporary medical discourses surrounding the theme of “maternal impression.” This essay seeks to reframe the text, placing it within historical discourses on masculinity, the body, and heterosexuality, and their intersections with colonial discourses on race and whiteness. Such a reading illuminates the complex construction of and multiple threats to urban bourgeois masculinity, masculine hegemony and the control of women, and the influence of colonial discourses on this empire without colonies. Re‐contextualized within its historical discourses, the essay proposes that the novella needs to be understood as a damning indictment of white western masculinity in fin‐de‐siècle Austria.
The Elusive Experience of Agency
Authors: Briscoe Robert E.
Published: March 2011

I here present some doubts about whether Mandik’s (2010) proposed intermediacy and recurrence constraints are necessary and sufficient for agentive experience. I also argue that in order to vindicate the conclusion that agentive experience is an exclusively perceptual phenomenon (Prinz, 2007), it is not enough to show that the predictions produced by forward models of planned motor actions are conveyed by mock sensory signals. Rather, it must also be shown that the outputs of “comparator” mechanisms that compare these predictions against actual sensory feedback are also coded in a perceptual representational format.
Semantics and Metaphysics in Informatics: Toward an Ontology of Tasks
Authors: Figdor Carrie
Published: March 2011

This article clarifies three principles that should guide the development of any cognitive ontology. First, that an adequate cognitive ontology depends essentially on an adequate task ontology; second, that the goal of developing a cognitive ontology is independent of the goal of finding neural implementations of the processes referred to in the ontology; and third, that cognitive ontologies are neutral regarding the metaphysical relationship between cognitive and neural processes.
Toward a Unified View of Cognitive Control
Authors: Salvucci Dario D. , Taatgen Niels A.
Published: March 2011

Allen Newell (1973) once observed that psychology researchers were playing “twenty questions with nature,” carving up human cognition into hundreds of individual phenomena but shying away from the difficult task of integrating these phenomena with unifying theories. We argue that research on cognitive control has followed a similar path, and that the best approach toward unifying theories of cognitive control is that proposed by Newell, namely developing theories in computational cognitive architectures. Threaded cognition, a recent theory developed within the ACT‐R cognitive architecture, offers promise as a unifying theory of cognitive control that addresses multitasking phenomena for both laboratory and applied task domains.
The Evolutionary Origins of Cognitive Control
Authors: Hills Thomas T.
Published: March 2011

The question of domain‐specific versus domain‐general processing is an ongoing source of inquiry surrounding cognitive control. Using a comparative evolutionary approach, Stout (2010) proposed two components of cognitive control: coordinating hierarchical action plans and social cognition. This article reports additional molecular and experimental evidence supporting a domain‐general attentional process coordinating hierarchical action plans, with the earliest such control processing originating in the capacity of dynamic foraging behaviors—predating the vertebrate‐invertebrate divergence (c. 700 million years ago). Further discussion addresses evidence required for additional, domain‐specific, cognitive control processes, noting that proposed social processes may simply provide emotionally valenced representational information to the above hierarchical process.
Why Reject a Sensory Imagery Theory of Control Consciousness?
Authors: Mylopoulos Myrto I.
Published: March 2011

Mandik (2010) defends a motor theory of control consciousness according to which nonsensory states, like motor commands, directly contribute to the awareness we have of ourselves as being in control of our actions. Along the way, he argues that his theory is to be preferred over Prinz’s (2007) sensory imagery theory, which denies that nonsensory states play any direct role in the generation of control consciousness. I argue that Mandik’s criticisms of Prinz’s theory fall short, but that nonetheless there are reasons to favor a motor theory of control consciousness over a sensory imagery theory.
Commentary: Performance Audit of PPPs – Getting the Basics Right
Authors: Barrett Pat
Published: March 2011

Performance auditing (PA) is an important vehicle for assessing Value for Money (VFM) of Public‐Private Partnerships (PPPs), as well as providing assurance to the Parliament and to the public about the accountability for the supporting strategic and operational frameworks. Experience to date with PPPs in Australia has been limited and mixed in terms of results. Few projects have reached the mature stage, let alone been completed. It has been suggested that we can learn from the audit approaches and systems developed by the National Audit Office in the UK. Australian Audit Offices need to ensure that they have robust PA/VFM auditing systems, analytical methodologies and tools in place to undertake quality evaluations at various stages of a PPP, but experience to date at federal and state levels also indicates that there is still a lot to do to get the basis elements of PPPs “right”.
Contribution of astrocytic glutamate and GABA uptake to corticostriatal information processing
Authors: Goubard Valérie , Fino Elodie , Venance Laurent
Published: March 2011

Non‐technical summary  The striatum is a part of the basal ganglia that receives input from the cerebral cortex, extracts relevant information from background noise and relays that information to other parts of the basal ganglia. It is largely composed of nerve cells known as medium‐sized spiny neurons (MSNs), and neurons from the cerebral cortex make synaptic connections with them. This study investigates the function of astrocytes at this synaptic connection, where their role is to remove the neurotransmitters glutamate and GABA that spills out from the synaptic cleft. It appears that astrocytes, via the uptake of neurotransmitters, increase the strength of filtering operated by MSNs.
Probing glycine receptor stoichiometry in superficial dorsal horn neurones using the spasmodic mouse
Authors: Graham B. A. , Tadros M. A. , Schofield P. R. , Callister R. J.
Published: March 2011

Non‐technical summary  Glycine receptors (GlyRs) play an important role in inhibiting neurone activity in the spinal cord. Until recently adult GlyRs were thought to comprise α1 and β subunits. A new form of the receptor containing α3 subunits has been discovered in the superficial dorsal horn (SDH), a region of the spinal cord important for pain. This raises questions about the precise subunit composition of GlyRs and glycinergic synapses in the SDH. We used the spasmodic mouse, where α1 subunit containing GlyRs have altered agonist sensitivity and electrophysiological properties, to ask how α1 and α3 subunits are assembled to form GlyRs on SDH neurones. We found most (∼75%) GlyRs and glycinergic synapses in the SDH contain α1 subunits and few are composed exclusively of α3 subunits. Therefore, future efforts to design pain drugs that target the α3 subunit must consider the potential interaction between α1 and α3 subunits in the GlyR.
Stochastic Stability and Stabilization of Uncertain Jump Linear Delay Systems via Delay Decomposition
Authors: Wang Jun-Wei , Wu Huai-Ning , Luo Yue-Sheng
Published: March 2011

This paper studies the problem of robustly stochastic stability and stabilization for a class of uncertain Markov jump linear systems with time delay. A new stochastic Lyapunov–Krasovskii functional (LKF) is constructed for the stability analysis and stabilization, in which the delay is uniformly divided into multiple segments. Based on this LKF and using an improved Jensen's integral inequality, the improved delay-dependent stochastic stability criteria are first derived in terms of linear matrix inequalities (LMIs). Then, an LMI approach to the design of stabilizing controllers via delayed state feedback is developed. The previous stability criteria are extended to give the delay-dependent stabilization conditions in terms of LMIs. Furthermore, an LMI optimization algorithm is proposed to find the maximum allowable delay of the system. Finally, numerical examples show that the proposed results are effective and much less conservative than some existing results.
From Chip to Cooling Tower Data Center Modeling: Influence of Server Inlet Temperature and Temperature Rise Across Cabinet
Authors: Breen Thomas J. , Walsh Ed J. , Punch Jeff , Shah Amip J. , Bash Cullen E.
Published: March 2011

To achieve reductions in the power consumption of the data center cooling infrastructure, the current strategy in data center design is to increase the inlet temperature to the rack, while the current strategy for energy-efficient system thermal design is to allow increased temperature rise across the rack. Either strategy, or a combination of both, intuitively provides enhancements in the coefficient of performance of the data center in terms of computing energy usage relative to cooling energy consumption. However, this strategy is currently more of an empirically based approach from practical experience, rather than a result of a good understanding of how the impact of varying temperatures and flow rates at rack level influences each component in the chain from the chip level to the cooling tower. The aim of this paper is to provide a model to represent the physics of this strategy by developing a modeling tool that represents the heat flow from the rack level to the cooling tower for an air cooled data center with chillers. This model presents the performance of a complete data center cooling system infrastructure. After detailing the model, two parametric studies are presented that illustrate the influence of increasing rack inlet air temperature, and temperature rise across the rack, on different components in the data center cooling architecture. By considering the total data center, and each component’s influence on the greater infrastructure, it is possible to identify the components that contribute most to the resulting inefficiencies in the heat flow from chip to cooling tower and thereby identify the components in need of possible redesign. For the data center model considered here it is shown that the strategy of increasing temperature rise across the rack may be a better strategy than increasing inlet temperature to the rack.
Supercavitating Vehicles With Noncylindrical, Nonsymmetric Cavities: Dynamics and Instabilities
Authors: Nguyen Vincent , Balachandran Balakumar
Published: March 2011

Cavity-wall interactions play an important role in determining the dynamics of supercavitating vehicles. To date, supercavitating vehicle system models make use of constant cylindrical cavities. As a further step, in this work, a dive-plane model with noncylindrical and nonsymmetric cavity shapes is developed. Cavitator angle of attack effects are considered, and a noncylindrical planing force model is incorporated. The system dynamics is examined in terms of nonlinear instabilities and the tail-slap phenomenon, and it is shown that the cavity shape plays a critical role in determining the system dynamics. The effectiveness of feedback control strategies with fin and cavitator inputs to achieve vehicle stability is also discussed.
Design and Prototyping of a Force-Reflecting Hand-Controller for Ultrasound Imaging
Authors: Najafi Farshid , Sepehri Nariman
Published: March 2011

This paper presents detailed design, analysis, prototyping, and testing of a novel force-reflecting hand-controller allowing physicians to control a robotic wrist and perform ultrasound examinations on patients in remote locations. The proposed device is a four degree-of-freedom mechanism with a fixed center-of-motion and uses symmetric parallel mechanisms. All movements of the device are kinematically decoupled, i.e., the hand-controller has independent drive systems for each standard ultrasound motion. A technique has been adapted to statically balance the weight of the device over its entire workspace using a single tension spring. The prototype of the device has been constructed and evaluated for ultrasound imaging of kidney and spleen. Maximum and accuracy of the output force are analytically determined and performance of the device in terms of static balancing, static-friction break-away force, and maximum achievable impedances are experimentally evaluated.
Improved Packaging Design for Maximizing the Thermal Performance of Multifinger Collector-Up HBTs
Authors: Tseng Hsien-Cheng
Published: March 2011

Advanced collector-up (C-up) heterojunction bipolar transistors (HBTs) with the thermal-via configuration (TVC) have been analyzed using a genetic algorithm (GA). Novel packaging structures are presented and evaluated in detail. With careful optimization, the thermal performance can be maximized by improving the thermal resistance over 40%, and the conventional TVC can be further reduced by 35%. The proposed approach is demonstrated on the multifinger InGaP/GaAs C-up HBT, which is attractive as the active component in power amplifiers. A comparison of measured, finite-element-calculated, and GA-extracted results has been made. Consequently, it is shown that the remarkable thermal management can be achieved with a miniature heat-dissipation design, and the thermally stable InGaP/GaAs C-up HBT should be feasible for implementation in intelligent wireless communication systems.
Development of Criteria for Lamina Emergent Mechanism Flexures With Specific Application to Metals
Authors: Ferrell Devin B. , Isaac Yanal F. , Magleby Spencer P. , Howell Larry L.
Published: March 2011

This paper develops new design criteria for lamina emergent mechanism (LEM) flexures with particular application to sheet-metal-formed metal flexures. The LEM flexure design criteria are based on the relative performance between the LEM flexure and a section of lamina that is of the same overall length, width, and thickness as the LEM flexure. Novel metal revolute and torsional LEM flexures are presented and evaluated against the LEM flexure design criteria. Both flexures meet the proposed criteria, and their performance is evaluated in the design of a basic crank-slider mechanism. When compared with unformed flexures of the same dimensions, the revolute and torsional metal LEM flexures are found to improve the crank-slider performance.
Numerical Analysis of Entropy Generation in Array of Pin-Fin Heat Sinks for Some Different Geometries
Authors: Kamali Reza , Barari Bamdad , Abbasian Shirazi Ashkan
Published: March 2011

In this study, Numerical analysis has been used to investigate entropy generation for array of pin-fin heat sink. Technique is applied to study the thermodynamic losses caused by heat transfer and pressure drop in pin-fin heat sinks. A general expression for the entropy generation rate is obtained by considering the whole heat sink as a control volume and applying the conservation equations for mass and energy with the entropy balance. Analytical and empirical correlations for heat transfer coefficients and friction factors are used in the numerical modeling. Also effects of heat transfer and pressure drop in entropy generation in control volume over pin-fins have been studied. Numerical analysis has been used for three different models of pin-fin heat sinks. The models are different in cross section area. These cross section areas are circle, horizontal ellipse and vertical ellipse which mentioned in next sections. Reference velocity used in Reynolds number and pressure drop is based on the minimum free area available for the fluid flow. Also for numerical analysis in-line arrangement of fins has been investigated and their relative performance is compared. At the end, the performance of these three models has been compared.
Numerical Analysis of CH4 and Air Combustion Inside a Small Tube With a Temperature Gradient
Authors: Feng Liang , Liu Zhongliang , Li Yanxia
Published: March 2011

A numerical study on CH4 and air premixed combustion inside a small tube with a temperature gradient was undertaken to investigate the effects of inlet velocity, equivalence ratio and combustor size. The simulation results show that the inlet velocity has a significant influence on the reaction zone, and the flame front shifts downstream as the inlet velocity increases. The results also show that, the inlet velocity has no obvious effects on the flame temperature. The highest flame temperature is obtained if the equivalence ratio is set to 1. It is disclosed that the combustor size has a very strong effect on combustion characteristics. The smaller the combustor size is, the more difficult it is to maintain the steady combustion. The smallest combustor size that the stable flame can be sustained is determined mainly by the wall temperature of the microcombustor under the given conditions, and the higher the wall temperature is, the smaller the smallest combustor size. Therefore raising wall temperature is an effective way to realize flame stabilization for a given combustor size.
Lower Entropy Generation in Microchannels With Laminar Single Phase Flow
Authors: Galvis E. , Culham J. R.
Published: March 2011

In this study the entropy generation minimization method is used to find the optimum channel dimensions in micro heat exchangers with a uniform heat flux. With this approach, pressure drop and heat transfer in the micro channels are considered simultaneously during the optimization analysis. A computational model is developed to find the optimum channel depth knowing other channel geometry dimensions and coolant inlet properties. The flow is assumed laminar and both hydrodynamically and thermally fully developed and incompressible. However, to take into account the effect of the developing length in the friction losses, the Hagenbach’s factor is introduced. The micro channels are assumed to have an isothermal or isoflux boundary condition, non-slip flow, and fluid properties have dependency on temperature accordingly. For these particular case studies, the pressure drop and heat transfer coefficient for the isoflux boundary condition is higher than the isothermal case. Higher heat transfer coefficient and pressure drop were found when the channel size decreased. The optimum channel geometry that minimizes the entropy generation rate tends to be a deep, narrow channel.
Three-Dimensional Aerodynamic Optimization for Axial-Flow Compressors Based Upon the Inverse Design and the Aerodynamic Variables
Authors: He Liu , Shan Peng
Published: March 2011

Integrating a genetic algorithm code with a response surface methodology code based upon the artificial neural network model, this paper develops an optimization system. By introducing a quasi-three dimensional through-flow design code and a design code of axial compressor airfoils with camber lines of arbitrary shape, and involving a three-dimensional computational fluid dynamics solver, this paper establishes a numerical aerodynamic optimization platform for the three-dimensional blades of axial compressors. The optimization in this paper mainly has four features. First, it applies the conventional inverse design method instead of the common computer aided design parameterization method to generate a three-dimensional blade. Second, it chooses aerodynamic parameters with physical meaning as optimization design variables instead of purely geometrical parameters. Third, it presents a stage-by-stage optimization strategy about the multistage turbomachinery optimization. Fourth, it introduces the visual sensitivity analysis method into optimization, which can adjust variation ranges of variables by analysing how great the variables influence the objective function. The above techniques were applied to the redesign of a single rotor row and two double-stage axial fans separately. The departure angles and work distributions in the inverse design were taken as design variables separately in optimizations of the single rotor and double-stage fans, and they were parametrically represented by means of Be´zier curves, whose parameters were used as the optimization variables in the practical operation. The three investigated examples elucidate that not only the techniques mentioned above are appropriate and effective in engineering, but also the design guidance for similar inverse design problems can be obtained from the optimization results.
Numerical Investigation of Turbulence Models for Minichannels
Authors: Deniz Emrah , Pehlivanoglu Nur
Published: March 2011

Due to having considerably small diameters compared to the macro channels; validation of conventional models and correlations and, examination of heat transfer and flow characteristics for mini/micro channels have been an attractive subject for last decades. In this study, classical turbulence models are compared and applicability of the conventional correlations is investigated for the flow through minichannels having diameter range between 1.2 and 0.25 mm. For the flow considered, fluid (R134a) enters the horizontal channel with a prescribed temperature and velocity, absorbs heat from the surrounding and then leaves the channel. Reynolds number is chosen in a range between 5000 and 20000 in order to cover the turbulent regime. For the first step of the study, in order to investigate the use of conventional turbulence models, Standard k-ε, RNG k-ε, Realizable k-ε, Standard k-w and Reynolds Stress models are employed to estimate friction factor and Nusselt number values for 0.5 mm diameter channel. These numerical results are compared with those calculated by conventional correlations existing in the literature. According to the comparison, none of the models create a dramatically deviation and Standard k-ε is determined as the model giving the closest results to the conventional values. As second step of the study, Standard k-ε model is applied for the flow through the minichannels having diameter of 1.2, 1, 0.8, 0.5 and 0.25 mm, respectively. Friction factor and Nusselt number values estimated numerically via Standard k-ε model are compared with those calculated by conventional correlations and existing relevant experimental data. According to the study, it is concluded that the numerical friction factor values are found to be close to the conventional values. The most discrepancy exists when diameter is less than and equal to 0.5 mm. Furthermore, numerical Nusselt number values are found to be close to conventional values estimated with the correlation proposed by Gnielinski (1976) while they are lower estimated for channels having diameter of 1.2, 1 and 0.8 mm and over estimated for 0.5 and 0.25 mm diameter channels. As a result, conventional correlations and turbulence models are found to be applicable for the diameter range and the flow investigated.
Instability in Parallel Channel System
Authors: Guo Yun , Xia Genglei , Zeng Heyi , Hu Miao
Published: March 2011

In this paper, the investigation on the instability in parallel channel system is summarized systematically. This phenomenon in parallel channel system is very typical, interesting and challengeable. The experiment data of a twin-channel system is used as the validation. Two typical methods are adopted to simulate this phenomenon for deciding the instability boundary. One is the integral method, which is based on the model of Clausse and Lahey and developed by Lee and Pan and GUO; the other is the classical system analysis code: Relap5/MOD3.4. In the experiment the influences of inlet resistance, system pressure and nonuniform heating are obtained. The influences of system pressure and inlet resistance can be simulated by both methods. However, there are some differences between the results of two methods. And for the effects of nonuniform heating and asymmetric inlet resistances, which are very popular in the nuclear power system, the results of numerical methods cannot get a good numerical agreement with those of experiment. It should be noticed in the practical engineering design. Finally, the typical “Ledinegg” instability phenomenon may occur in the parallel channel system according to the numerical results. Sometimes it will induce the burnout before the parallel channel instability. Both methods predict the same tendency. And a detailed explanation is given. The slope of the pressure drop-mass flux curve is the key to avoid the flow excursion phenomenon in parallel channel system.