bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase coherence and energy relaxation in epitaxial graphene under microwave radiation
Authors: Eless V. , Yager T. , Spasov S. , Lara-Avila S. , Yakimova R. , Kubatkin S. , Janssen T. J. B. M. , Tzalenchuk A. , Antonov V.
Published: August 2013

We have performed low-temperature magnetotransport measurements on monolayer epitaxial graphene under microwave radiation and extracted the radiation-induced effective temperatures, energy relaxation, and the dephasing times. We established that the response of the graphene sample is entirely bolometric at least up to 170 GHz. Dynamic dephasing, i.e., the time-reversal symmetry breaking effect of the ac electromagnetic field rather than mediated by heating, may become significant in the terahertz frequency range and in samples with longer phase coherence time.
Time structure of fast domain wall creation by localized fields in a magnetic nanowire
Authors: Bocklage Lars , Stein Falk-Ulrich , Martens Michael , Matsuyama Toru , Meier Guido
Published: August 2013

We have investigated the generation of magnetic domain walls by nanosecond magnetic field pulses of a strip line. Domain wall creation is sensitive to an externally applied field concerning wall type and threshold amplitudes. The domain wall creation is stochastic similar to domain wall depinning. In the experiment reliable domain wall generation require up to 8 ns long pulses at the threshold field amplitude. The required pulse length can be reduced by higher field amplitudes. Time-resolved measurements and micromagnetic simulations show that the domain wall is generated within three nanoseconds. The creation proceeds via vortex core formation under the strip line.
Electrical characterization of ensemble of GaN nanowires grown by the molecular beam epitaxy technique
Authors: Kolkovsky Vl. , Zytkiewicz Z. R. , Sobanska M. , Klosek K.
Published: August 2013

High quality Schottky contacts are formed on GaN nanowires (NWs) structures grown by the molecular beam epitaxy technique on Si(111) substrate. The current-voltage characteristics show the rectification ratio of about 103 and the leakage current of about 10−4 A/cm2 at room temperature. From the capacitance-voltage measurements the free carrier concentration in GaN NWs is determined as about 1016 cm−3. Two deep levels (H200 and E280) are found in the structures containing GaN NWs. H200 is attributed to an extended defect located at the interface between the substrate and SiNx or near the sidewalls at the bottom of the NWs whereas E280 is tentatively assigned to a gallium-vacancy- or nitrogen interstitials-related defect.
Defects in 6LiInSe2 neutron detector investigated by photo-induced current transient spectroscopy and photoluminescence
Authors: Cui Yunlong , Bhattacharya Pijush , Buliga Vladimir , Tupitsyn Eugene , Rowe Emmanuel , Wiggins Brenden , Johnstone Daniel , Stowe Ashley , Burger Arnold
Published: August 2013

6LiInSe2 is a promising thermal neutron semiconductor detector material. The performance of the detector is affected by the carrier mobility-lifetime products. Therefore, defects that function as carrier recombination centers need to be identified. In this letter, characterization of defect levels in 6LiInSe2 by photo-induced current transient spectroscopy (PICTS) and photoluminescence is reported. PICTS measurements revealed electron-related defects located at 0.22, 0.36, and 0.55 eV and hole-related defects at 0.19, 0.30, and 0.73 eV. Free exciton and donor-acceptor pairs (DAP) emissions were observed. The PICTS defect level values are consistent with those extracted from DAP transitions.
3d-4f spin interaction induced giant magnetocaloric effect in zircon-type DyCrO4 and HoCrO4 compounds
Authors: Midya A. , Khan N. , Bhoi D. , Mandal P.
Published: August 2013

We have investigated the influence of 3d-4f spin interaction on magnetic and magnetocaloric properties of DyCrO4 and HoCrO4 compounds by magnetization and heat capacity measurements. Both the compounds exhibit complicated magnetic properties and huge magnetic entropy change around the ferromagnetic transition due to the strong competition between ferromagnetic and antiferromagnetic superexchange interactions. For a field change of 8 T, the maximum values of magnetic entropy change (ΔSMmax), adiabatic temperature change (ΔTad), and refrigerant capacity (RC) reach 29 J kg−1 K−1, 8 K, and 583 J kg−1, respectively, for DyCrO4 whereas the corresponding values for HoCrO4 are 31 J kg−1 K−1, 12 K, and 622 J kg−1. ΔSMmax, ΔTad, and RC are also quite large for a moderate field change. The large values of magnetocaloric parameters suggest that the zircon-type DyCrO4 and HoCrO4 could be the potential magnetic refrigerant materials for liquefaction of hydrogen.
Anisotropic permittivity of ultra-thin crystalline Au films: Impacts on the plasmonic response of metasurfaces
Authors: Campbell Sawyer D. , Ziolkowski Richard W. , Cao Jiangrong , Laref Slimane , Muralidharan Krishna , Deymier Pierre
Published: August 2013

It has been determined by density functional theory (DFT) simulations that the extracted permittivities of ultra-thin crystalline gold (Au) films exhibit large anisotropies which are not predicted by classical models or previous experimental determinations of the dielectric function. The optical scattering characteristics of a periodic array of Au discs are simulated with the DFT extracted permittivity and contrasted against those obtained with several commonly used Au permittivity models. It is demonstrated that the DFT-based transmittance spectra for these plasmonic metasurfaces lead to significantly redshifted results when compared to those predicted by standard Drude and Johnson-Christy permittivity models.
Enhanced thermal stability of extreme ultraviolet multilayers by balancing diffusion-induced structural changes
Authors: Nyabero S. L. , van de Kruijs R. W. E. , Yakshin A. E. , Bijkerk F.
Published: August 2013

A multilayer design that compensates period thickness compaction at elevated temperatures is presented. The design is based on a reference multilayer that exhibits compaction upon thermal loading and includes an additional sub-structure, which expands upon thermal loading to compensate for the basic compaction. Using extreme ultraviolet reflecting multilayers as an example, the optimization of the ratio of the number of the expanding Mo/B4C periods to that of compacting B4C-barriered Mo/Si periods is demonstrated. Both the average periodicity and the centroid wavelength of the composite multilayer were preserved during annealing at 250 °C for 60 h.
Synthesis of Chiral 1,2-Dihydronaphtho[2,1-b]furans by Organocatalytic Domino Reactions Catalyzed with Multiple Catalysis
Authors: Pan Jin-Yun , Li Xin-Sheng , Xu Dong-Cheng , Xie Jian-Wu
Published: August 2013

A chiral multiple catalysis with two chiral units has been proved effective in the domino Friedel–Crafts alkylation of β-naphthols with α-bromonitroalkenes. This novel and efficient domino reaction affords chiral 1,2-dihydronaphtho[2,1-b]furans in good to high yields and enantioselectivities (up to 93 % yield, 91 % enantiomeric excess).
Mitochondrial SIRT5 is present in follicular cells and is altered by reduced ovarian reserve and advanced maternal age
Authors: Pacella-Ince Leanne , Zander-Fox Deirdre L. , Lane Michelle
Published: August 2013

Women with reduced ovarian reserve or advanced maternal age have an altered metabolic follicular microenvironment. As sirtuin 5 (SIRT5) senses cellular metabolic state and post-translationally alters protein function, its activity may directly impact on oocyte viability and pregnancy outcome. Therefore, we investigated the role of SIRT5 in relation to ovarian reserve and maternal age. Women (n = 47) undergoing routine IVF treatment were recruited and allocated to one of three cohorts based on ovarian reserve and maternal age. Surplus follicular fluid, granulosa and cumulus cells were collected. SIRT5 mRNA, protein and protein activity was confirmed in granulosa and cumulus cells via qPCR, immunohistochemistry, western blotting and desuccinylation activity. The presence of carbamoyl phosphate synthase I (CPS1), a target of SIRT5, was investigated by immunohistochemistry and follicular-fluid ammonium concentrations determined via microfluorometry. Women with reduced ovarian reserve or advanced maternal age had decreased SIRT5 mRNA, protein and desuccinylation activity in granulosa and cumulus cells resulting in an accumulation of follicular-fluid ammonium, presumably via alterations in activity of a SIRT5 target, CPS1, which was present in granulosa and cumulus cells. This suggests a role for SIRT5 in influencing oocyte quality and IVF outcomes.
Tapping unsustainable groundwater stores for agricultural production in the High Plains Aquifer of Kansas, projections to 2110
Authors: Steward David R. , Bruss Paul J. , Yang Xiaoying , Staggenborg Scott A. , Welch Stephen M. , Apley Michael D.
Published: August 2013

Significance

Society faces the multifaceted crossroads dilemma of sustainably balancing today’s livelihood with future resource needs. Currently, agriculture is tapping the High Plains Aquifer beyond natural replenishment rates to grow irrigated crops and livestock that augment global food stocks, and science-based information is needed to guide choices. We present new methods to project trends in groundwater pumping and irrigated corn and cattle production. Although production declines are inevitable, scenario analysis substantiates the impacts of increasing near-term water savings, which would extend the usable lifetime of the aquifer, increase net production, and generate a less dramatic production decline.
Money and trust among strangers
Authors: Camera Gabriele , Casari Marco , Bigoni Maria
Published: August 2013

What makes money essential for the functioning of modern society? Through an experiment, we present evidence for the existence of a relevant behavioral dimension in addition to the standard theoretical arguments. Subjects faced repeated opportunities to help an anonymous counterpart who changed over time. Cooperation required trusting that help given to a stranger today would be returned by a stranger in the future. Cooperation levels declined when going from small to large groups of strangers, even if monitoring and payoffs from cooperation were invariant to group size. We then introduced intrinsically worthless tokens. Tokens endogenously became money: subjects took to reward help with a token and to demand a token in exchange for help. Subjects trusted that strangers would return help for a token. Cooperation levels remained stable as the groups grew larger. In all conditions, full cooperation was possible through a social norm of decentralized enforcement, without using tokens. This turned out to be especially demanding in large groups. Lack of trust among strangers thus made money behaviorally essential. To explain these results, we developed an evolutionary model. When behavior in society is heterogeneous, cooperation collapses without tokens. In contrast, the use of tokens makes cooperation evolutionarily stable.
Learning-induced neural plasticity of speech processing before birth
Authors: Partanen Eino , Kujala Teija , Näätänen Risto , Liitola Auli , Sambeth Anke , Huotilainen Minna
Published: August 2013

Significance

Learning, the foundation of adaptive and intelligent behavior, is based on changes in neural assemblies and reflected by the modulation of electric brain responses. In infancy, long-term memory traces are formed by auditory learning, improving discrimination skills, in particular those relevant for speech perception and understanding. Here we show direct neural evidence that neural memory traces are formed by auditory learning prior to birth. Our findings indicate that prenatal experiences have a remarkable influence on the brain’s auditory discrimination accuracy, which may support, for example, language acquisition during infancy. Consequently, our results also imply that it might be possible to support early auditory development and potentially compensate for difficulties of genetic nature, such as language impairment or dyslexia.
Comparative genomics boosts target prediction for bacterial small RNAs
Authors: Wright Patrick R. , Richter Andreas S. , Papenfort Kai , Mann Martin , Vogel Jörg , Hess Wolfgang R. , Backofen Rolf , Georg Jens
Published: August 2013

Significance

This study presents a unique approach (CopraRNA, for Comparative Prediction Algorithm for sRNA Targets) towards reliably predicting the targets of bacterial small regulatory RNAs (sRNAs). These molecules are important regulators of gene expression. Their detailed analysis thus far has been hampered by the lack of reliable algorithms to predict their mRNA targets. CopraRNA integrates phylogenetic information to predict sRNA targets at the genomic scale, reconstructs regulatory networks upon functional enrichment and network analysis, and predicts the sRNA domains for target recognition and interaction. Our results demonstrate that CopraRNA substantially improves the bioinformatic prediction of target genes and opens the field for the application to nonmodel bacteria.
Cone photoreceptor types in zebrafish are generated by symmetric terminal divisions of dedicated precursors
Authors: Suzuki Sachihiro C. , Bleckert Adam , Williams Philip R. , Takechi Masaki , Kawamura Shoji , Wong Rachel O. L.
Published: August 2013

Significance

Color vision requires multiple types of cone photoreceptors, each with peak sensitivity to a specific wavelength. How different cone types are generated in vivo is not clear. We show that there are precursor cells individually dedicated to producing a single cone type. We tracked cone genesis in vivo in transgenic zebrafish in which red cones and their progenitors express fluorescent protein driven by the thyroid hormone receptor β2 promoter. We discovered that red cones are generated by symmetric terminal divisions of a red-cone precursor. Moreover, UV, blue, and green cones also have their own dedicated precursors. Thyroid hormone receptor β2 expression in cone precursors is required to produce pure red cones, whereas expression after cell division results in cones with mixed opsins.
Eddy current and coupled landscapes for nonadiabatic and nonequilibrium complex system dynamics
Authors: Zhang Kun , Sasai Masaki , Wang Jin
Published: August 2013

Physical and biological systems are often involved with coupled processes of different time scales. In the system with electronic and atomic motions, for example, the interplay between the atomic motion along the same energy landscape and the electronic hopping between different landscapes is critical: the system behavior largely depends on whether the intralandscape motion is slower (adiabatic) or faster (nonadiabatic) than the interlandscape hopping. For general nonequilibrium dynamics where Hamiltonian or energy function is unknown a priori, the challenge is how to extend the concepts of the intra- and interlandscape dynamics. In this paper we establish a theoretical framework for describing global nonequilibrium and nonadiabatic complex system dynamics by transforming the coupled landscapes into a single landscape but with additional dimensions. On this single landscape, dynamics is driven by gradient of the potential landscape, which is closely related to the steady-state probability distribution of the enlarged dimensions, and the probability flux, which has a curl nature. Through an example of a self-regulating gene circuit, we show that the curl flux has dramatic effects on gene regulatory dynamics. The curl flux and landscape framework developed here are easy to visualize and can be used to guide further investigation of physical and biological nonequilibrium systems.
Cognitive emotion regulation fails the stress test
Authors: Raio Candace M. , Orederu Temidayo A. , Palazzolo Laura , Shurick Ashley A. , Phelps Elizabeth A.
Published: August 2013

Cognitive emotion regulation has been widely shown in the laboratory to be an effective way to alter the nature of emotional responses. Despite its success in experimental contexts, however, we often fail to use these strategies in everyday life where stress is pervasive. The successful execution of cognitive regulation relies on intact executive functioning and engagement of the prefrontal cortex, both of which are rapidly impaired by the deleterious effects of stress. Because it is specifically under stressful conditions that we may benefit most from such deliberate forms of emotion regulation, we tested the efficacy of cognitive regulation after stress exposure. Participants first underwent fear-conditioning, where they learned that one stimulus (CS+) predicted an aversive outcome but another predicted a neutral outcome (CS−). Cognitive regulation training directly followed where participants were taught to regulate fear responses to the aversive stimulus. The next day, participants underwent an acute stress induction or a control task before repeating the fear-conditioning task using these newly acquired regulation skills. Skin conductance served as an index of fear arousal, and salivary α-amylase and cortisol concentrations were assayed as neuroendocrine markers of stress response. Although groups showed no differences in fear arousal during initial fear learning, nonstressed participants demonstrated robust fear reduction following regulation training, whereas stressed participants showed no such reduction. Our results suggest that stress markedly impairs the cognitive regulation of emotion and highlights critical limitations of this technique to control affective responses under stress.
Arginase regulates red blood cell nitric oxide synthase and export of cardioprotective nitric oxide bioactivity
Authors: Yang Jiangning , Gonon Adrian T. , Sjöquist Per-Ove , Lundberg Jon O. , Pernow John
Published: August 2013

Significance

Nitric oxide from endothelial cells is important for regulating cardiovascular function. Recent data suggest that red blood cells are a source for nitric oxide. We examined the function of red blood cell nitric oxide and the regulation of its formation by the enzyme arginase. We show that red blood cells contain arginase that inhibits nitric oxide export. The function was tested in a heart model subjected to ischemia. The recovery of heart function after ischemia was improved following inhibition of red blood cell arginase. This effect depended on the specific protein producing nitric oxide. The results demonstrate an important function by red blood cells in regulating heart function during ischemia via nitric oxide production under tight control by arginase.
Structure of the transition state for the binding of c-Myb and KIX highlights an unexpected order for a disordered system
Authors: Giri Rajanish , Morrone Angela , Toto Angelo , Brunori Maurizio , Gianni Stefano
Published: August 2013

Significance

A considerable fraction of proteins, although functional, does not display a well-ordered native state, posing the structure–function dogma into question. Although different models have been described, the role of protein disorder is still shrouded in mystery. Here, we investigate the mechanism of recognition between an intrinsically unstructured protein and its partner. Unexpectedly, we found the binding to occur with a very high degree of geometrical precision, suggesting that a potential value of disorder is not, in this case, to be searched in the speeding up of the reaction thanks to an increased capture radius. Given that in the cell disordered polypeptides may be more vulnerable than folded domains, the advantage in being natively unfolded remains a conundrum.
Complement modulates the cutaneous microbiome and inflammatory milieu
Authors: Chehoud Christel , Rafail Stavros , Tyldsley Amanda S. , Seykora John T. , Lambris John D. , Grice Elizabeth A.
Published: August 2013

Significance

Healthy skin is colonized by a diversity of microbiota. Little is known regarding how the host immune response influences the skin microbiota. We demonstrate a role for complement, a key component of innate immunity, in host–microbe interactions of the skin. Inhibiting a key component of the complement cascade reduced diversity and altered composition of the skin microbiota, parallel to a reduction in skin inflammatory cell infiltration and downregulation of skin defense and immune gene expression. Further, we find that the commensal skin microbiota regulates the expression of complement genes in the skin. These results suggest an interactive role between complement and the microbial ecosystem of the skin and could have important implications for inflammatory and/or infectious skin disorders.
Overlapping gene coexpression patterns in human medullary thymic epithelial cells generate self-antigen diversity
Authors: Pinto Sheena , Michel Chloé , Schmidt-Glenewinkel Hannah , Harder Nathalie , Rohr Karl , Wild Stefan , Brors Benedikt , Kyewski Bruno
Published: August 2013

Significance

The ability of the immune system to distinguish self from foreign (“self-tolerance”) is largely established in the thymus, a primary lymphoid organ where T cells develop. Intriguingly, T cells encounter most tissue-specific constituents already in the thymus, thus imposing a broad scope of tolerance before T cells circulate through the body. This preemption of the “immunological self” is afforded by the “promiscuous” expression of numerous tissue-specific antigens in medullary thymic epithelial cells. Here, we identified principles by which promiscuous gene expression at the single-cell level adds up to the full diversity of self-antigens displayed at the population level.
Expanding the primate body schema in sensorimotor cortex by virtual touches of an avatar
Authors: Shokur Solaiman , O’Doherty Joseph E. , Winans Jesse A. , Bleuler Hannes , Lebedev Mikhail A. , Nicolelis Miguel A. L.
Published: August 2013

The brain representation of the body, called the body schema, is susceptible to plasticity. For instance, subjects experiencing a rubber hand illusion develop a sense of ownership of a mannequin hand when they view it being touched while tactile stimuli are simultaneously applied to their own hand. Here, the cortical basis of such an embodiment was investigated through concurrent recordings from primary somatosensory (i.e., S1) and motor (i.e., M1) cortical neuronal ensembles while two monkeys observed an avatar arm being touched by a virtual ball. Following a period when virtual touches occurred synchronously with physical brushes of the monkeys' arms, neurons in S1 and M1 started to respond to virtual touches applied alone. Responses to virtual touch occurred 50 to 70 ms later than to physical touch, consistent with the involvement of polysynaptic pathways linking the visual cortex to S1 and M1. We propose that S1 and M1 contribute to the rubber hand illusion and that, by taking advantage of plasticity in these areas, patients may assimilate neuroprosthetic limbs as parts of their body schema.
Structural insights into the interaction of IL-33 with its receptors
Authors: Liu Xi , Hammel Michal , He Yanfeng , Tainer John A. , Jeng U-Ser , Zhang Linqi , Wang Shuying , Wang Xinquan
Published: August 2013

Significance

Interleukin (IL)-33 exerts its biological effects by binding to its specific primary receptor ST2 and the coreceptor IL-1 receptor accessory protein (IL-1RAcP). Through determining the crystal structure of IL-33 with ST2, we define the molecular basis for their specific recognition and propose that surface-charge complementarity is critical in determining ligand-binding specificity of IL-1 primary receptors. Small-angle X-ray–scattering studies also reveal that ST2 possesses significant interdomain flexibility, which is not present in the coreceptor IL-1RAcP. These molecular features are consistent with their respective roles in ligand binding and signal transduction on cell surface. Small-angle X-ray–scattering results also support and extend a detailed stepwise model for ligand–receptor assembly and activation in the IL-1 family.
The transcription factor Interferon Regulatory Factor 4 is required for the generation of protective effector CD8
+
T cells
Authors: Raczkowski Friederike , Ritter Josephine , Heesch Kira , Schumacher Valéa , Guralnik Anna , Höcker Lena , Raifer Hartmann , Klein Matthias , Bopp Tobias , Harb Hani , Kesper Dörthe A. , Pfefferle Petra I. , Grusdat Melanie , Lang Philipp A. , Mittrücker Hans-Willi , Huber Magdalena
Published: August 2013

Robust cytotoxic CD8
+
T-cell response is important for immunity to intracellular pathogens. Here, we show that the transcription factor IFN Regulatory Factor 4 (IRF4) is crucial for the protective CD8
+
T-cell response to the intracellular bacterium
Listeria monocytogenes
. IRF4-deficient (
Irf4

−/−

)
mice could not clear
L. monocytogenes
infection and generated decreased numbers of
L. monocytogenes
-specific CD8
+
T cells with impaired effector phenotype and function. Transfer of wild-type CD8
+
T cells into
Irf4

−/−

mice improved bacterial clearance, suggesting an intrinsic defect of CD8
+
T cells in
Irf4
−/−
mice. Following transfer into wild-type recipients,
Irf4
−/−
CD8
+
T cells became activated and showed initial proliferation upon
L. monocytogenes
infection. However, these cells could not sustain proliferation, produced reduced amounts of IFN-γ and TNF-α, and failed to acquire cytotoxic function. Forced IRF4 expression in
Irf4
−/−
CD8
+
T cells rescued the defect. During acute infection,
Irf4

−/−

CD8
+
T cells demonstrated diminished expression of B lymphocyte-induced maturation protein-1 (Blimp-1), inhibitor of DNA binding (Id)2, and T-box expressed in T cells (T-bet), transcription factors programming effector-cell generation. IRF4 was essential for expression of Blimp-1, suggesting that altered regulation of Blimp-1 contributes to the defects of
Irf4
−/−
CD8
+
T cells. Despite increased levels of B-cell lymphoma 6 (BCL-6), Eomesodermin, and Id3,
Irf4
−/−
CD8
+
T cells showed impaired memory-cell formation, indicating additional functions for IRF4 in this process. As IRF4 governs B-cell and CD4
+
T-cell differentiation, the identification of its decisive role in peripheral CD8
+
T-cell differentiation, suggests a common regulatory function for IRF4 in adaptive lymphocytes fate decision.
Contribution of solar radiation to decadal temperature variability over land
Authors: Wang Kaicun , Dickinson Robert E.
Published: August 2013

Significance

Global air temperature has become the primary metric for judging global climate change. The variability of global temperature on a decadal timescale is still poorly understood. This paper shows that surface incident solar radiation (Rs) over land globally peaked in the 1930s, substantially decreased from the 1940s to the 1970s, and changed little after that. The cooling effect of this reduction ofRsaccounts in part for the near-constant temperature from the 1930s into the 1970s. Since then, neither the rapid increase in temperature from the 1970s through the 1990s nor the slowdown of warming in the early twenty-first century appear to be significantly related to changes ofRs.
Protoribosome by quantum kernel energy method
Authors: Huang Lulu , Krupkin Miri , Bashan Anat , Yonath Ada , Massa Lou
Published: August 2013

Significance

The ribosome is essential to life as it functions as “the protein factory” that translates the genetic code into proteins. A universally conserved region around its major active site, where the nascent proteins are being created, was identified in all contemporary ribosomes. Thus, it seems to be a remnant of an entity from the prebiotic RNA world, hence called the “protoribosome.” Using quantum mechanics and crystal coordinates of this region, we aimed at answering the question of whether the putative protoribosome has properties essential to function as an evolutionary precursor to the modern ribosome. Our findings show that the necessary conditions that would characterize a practicable protoribosome, namely energetic structural stability and energetically stable attachment to substrates, are well satisfied.
Bidirectional communication between oocytes and ovarian follicular somatic cells is required for meiotic arrest of mammalian oocytes
Authors: Wigglesworth Karen , Lee Kyung-Bon , O’Brien Marilyn J. , Peng Jia , Matzuk Martin M. , Eppig John J.
Published: August 2013

Significance

The fertility of mammalian females depends upon the coordinated development of ovarian follicles and the developing eggs, called oocytes, contained within them. It has been known for many years that the somatic cells of follicles arrest the progression of meiosis in the oocyte until both the follicle and the oocyte are fully developed and ready for ovulation and fertilization. Here we show that, although the somatic compartment of ovarian follicles clearly plays an essential role in the maintenance of oocyte meiotic arrest, this function of the somatic cells is regulated by signals from the oocyte itself.
A history of bacterial meningitis from antiquity to modern times.
Authors: Christodoulides M.
Published: August 2013

This chapter outlines the history of bacterial meningitis, highlighting prevailing concepts during the period from Hippocrates to the Renaissance, and the major contributions of 18th- and 19th-century scientists (including Swiss and French scientists) toward understanding the signs, symptoms, pathogenesis, and bacterial aetiology of meningitis.
Evidence-based clinical examination of meningitis.
Authors: Curtis S.
Published: August 2013

This chapter describes the strength of evidence supporting the use of individual purported clinical features as diagnostic tests for meningitis, as used in the process of weighing an individual patient's risk of having the disease prior to the administration of the more definitive gold standard diagnostic test of cerebrospinal fluid analysis. The evidence is described in both children and adults, and recommendations for further research are given.
Streptococcus pneumoniae meningitis.
Authors: Klein M. , Hammerschmidt S. , Koedel U.
Published: August 2013

This chapter reviews the pathogenesis of Streptococcus pneumoniae meningitis, illustrating that, in order to infect the central nervous system via the bloodstream, the pathogen has first to colonize and then cross the mucosa of the nasopharynx, survive and proliferate in the bloodstream, pass the blood-brain barrier and/or blood-cerebrospinal fluid barrier, and finally replicate in the subarachnoid space. The cytokines, chemokines, reactive oxygen species, reactive nitrogen species, matrix metalloproteinases, and other biomolecules involved in the inflammatory process are described. Novel treatment strategies for pneumococcal meningitis are discussed, including the use of non-bacteriolytic antibiotics, antioxidants, and antiinflammatory agents.
Escherichia coli meningitis.
Authors: Kim K. S.
Published: August 2013

This chapter reviews the role of the blood-brain barrier (BBB) in Escherichia coli meningitis; the mechanisms of E. coli translocation of the BBB; the relationship between the magnitude of bacteraemia and the development of E. coli meningitis; E. coli binding to and invasion of human brain microvascular endothelial cells (HBMECs); functional genomics of E. coli; and strategies for preventing E. coli penetration into the brain.
The pathophysiology of tuberculous meningitis.
Authors: Thwaites G.
Published: August 2013

This chapter reviews current understanding of Mycobacterium tuberculosis translocation from lung to brain, the role of the granuloma in M. tuberculosis dissemination, M. tuberculosis invasion of the central nervous system, and the immunopathology of tuberculous meningitis.
Neurosyphilis.
Authors: Ang Wim Ang Wim
Published: August 2013

This chapter reviews the clinical types, diagnosis, treatment, pathogenesis, and immunopathology (immune evasion and induction) of neurosyphilis. Genetic variation in Treponema pallidum is also described.
Meningitis in neuroborreliosis.
Authors: Cadavid D.
Published: August 2013

This chapter describes the clinical aspects and antibiotic treatment of meningitis associated with Lyme disease and relapsing fever. Pathogen virulence factors, host immune response, and brain tissue damage involved in Borrelia meningitis are also discussed. Findings from mouse models of Borrelia meningitis are summarized.
Person‐centred counsellors' experiences of working with clients in crisis: A qualitative interview study
Authors: Carrick Lorna
Published: August 2013

Aims: This study aims to explore and understand person‐centred therapists’ experiences and work with clients at the pivotal point of crisis. Specifically: how do person‐centred therapists experience working with clients in crisis? Do they identify differences in crisis intervention compared to non‐crisis work? What do they perceive as helpful to crisis clients? How relevant are therapists' own experiences of crisis? Method: Participants were all experienced person‐centred therapists. Qualitative, semi‐structured interviews were conducted and the data were analysed qualitatively using person‐centred/phenomenological methodology. Results: Respondents identified differences in their experiences. Typically, therapists described polarity in their experience of danger and opportunity, also heightened energy levels within themselves, perceived higher levels of engagement, faster pace of work, experiences of reaching ‘relational depth’ earlier, and the importance of assisting symbolisation of clients' experience in awareness. Clients were experienced as vulnerable, unable to access previous coping mechanisms, in a state of breakdown and disintegration, but also as wide open, having dropped their usual defences, and more available to engage in therapy and enter the process of change and potential post‐crisis growth. Discussion: The findings are discussed in relation to prevailing models of crisis intervention, person‐centred theory and theoretical developments in post‐traumatic growth in the aftermath of crisis.
Comparing Performance in Discrete and Continuous Comparison Tasks
Authors: Leibovich Tali , Henik Avishai
Published: August 2013

The approximate number system (ANS) theory suggests that all magnitudes, discrete (i.e., number of items) or continuous (i.e., size, density, etc.), are processed by a shared system and comply with Weber's law. The current study reexamined this notion by comparing performance in discrete (comparing numerosities of dot arrays) and continuous (comparisons of area of squares) tasks. We found that: (a) threshold of discrimination was higher for continuous than for discrete comparisons; (b) while performance in the discrete task complied with Weber's law, performance in the continuous task violated it; and (c) performance in the discrete task was influenced by continuous properties (e.g., dot density, dot cumulative area) of the dot array that were not predictive of numerosities or task relevant. Therefore, we propose that the magnitude processing system (MPS) is actually divided into separate (yet interactive) systems for discrete and continuous magnitude processing. Further subdivisions are discussed. We argue that cooperation between these systems results in a holistic comparison of magnitudes, one that takes into account continuous properties in addition to numerosities. Considering the MPS as two systems opens the door to new and important questions that shed light on both normal and impaired development of the numerical system.
Drebrin contains a cryptic F-actin–bundling activity regulated by Cdk5 phosphorylation
Authors: Worth Daniel C. , Daly Catherine N. , Geraldo Sara , Oozeer Fazal , Gordon-Weeks Phillip R.
Published: August 2013

Drebrin is an actin filament (F-actin)–binding protein with crucial roles in neuritogenesis and synaptic plasticity. Drebrin couples dynamic microtubules to F-actin in growth cone filopodia via binding to the microtubule-binding +TIP protein EB3 and organizes F-actin in dendritic spines. Precisely how drebrin interacts with F-actin and how this is regulated is unknown. We used cellular and in vitro assays with a library of drebrin deletion constructs to map F-actin binding sites. We discovered two domains in the N-terminal half of drebrin—a coiled-coil domain and a helical domain—that independently bound to F-actin and cooperatively bundled F-actin. However, this activity was repressed by an intramolecular interaction relieved by Cdk5 phosphorylation of serine 142 located in the coiled-coil domain. Phospho-mimetic and phospho-dead mutants of serine 142 interfered with neuritogenesis and coupling of microtubules to F-actin in growth cone filopodia. These findings show that drebrin contains a cryptic F-actin–bundling activity regulated by phosphorylation and provide a mechanistic model for microtubule–F-actin coupling.
Crawling cells feel the squeeze
Authors: Leslie Mitch
Published: August 2013

Study finds that cells alter movement style in tight spaces.
CD4+ T cells are trigger and target of the glucocorticoid response that prevents lethal immunopathology in toxoplasma infection
Authors: Kugler David G. , Mittelstadt Paul R. , Ashwell Jonathan D. , Sher Alan , Jankovic Dragana
Published: August 2013

Synthetic glucocorticoids (GCs) are commonly used in the treatment of inflammatory diseases, but the role of endogenous GCs in the regulation of host-protective immune responses is poorly understood. Here we show that GCs are induced during acute Toxoplasma gondii infection and directly control the T cell response to the parasite. When infected with toxoplasma, mice that selectively lack GC receptor (GR) expression in T cells (GRlck-Cre) rapidly succumb to infection despite displaying parasite burdens indistinguishable from control animals and unaltered levels of the innate cytokines IL-12 and IL-27. Mortality in the GRlck-Cre mice was associated with immunopathology and hyperactive Th1 cell function as revealed by enhanced IFN-γ and TNF production in vivo. Unexpectedly, these CD4+ T lymphocytes also overexpressed IL-10. Importantly, CD4+ T cell depletion in wild-type or GRlck-Cre mice led to ablation of the GC response to infection. Moreover, in toxoplasma-infected RAG−/− animals, adoptive transfer of CD4+ T lymphocytes was required for GC induction. These findings establish a novel IL-10–independent immunomodulatory circuit in which CD4+ T cells trigger a GC response that in turn dampens their own effector function. In the case of T. gondii infection, this self-regulatory pathway is critical for preventing collateral tissue damage and promoting host survival.
Strawberry notch homologue 2 regulates osteoclast fusion by enhancing the expression of DC-STAMP
Authors: Maruyama Kenta , Uematsu Satoshi , Kondo Takeshi , Takeuchi Osamu , Martino Mikaël M. , Kawasaki Takumi , Akira Shizuo
Published: August 2013

Osteoclasts are multinucleated cells formed by fusion of mononuclear precursors in response to receptor activator of nuclear factor κB (NF-κB) ligand (RANKL). We found that RANKL induced expression of the DExD/H helicase family corepressor strawberry notch homologue 2 (Sbno2). Previous in vitro studies showed that Sbno2 is induced by IL-10 and is involved in NF-κB repression. However, the role of Sbno2 in vivo and its pleiotropic functions are unknown. Sbno2 gene targeting resulted in normal NF-κB activation by TLR ligands. However, Sbno2-deficient mice exhibited increased bone mass due to impaired osteoclast fusion. Expression of dendritic cell–specific transmembrane protein (DC-STAMP), a critical player in osteoclast fusion, was significantly attenuated, and cell fusion of Sbno2-deficient osteoclasts was rescued by DC-STAMP. Sbno2 directly bound to T cell acute lymphocytic leukemia 1 (Tal1) and attenuated its inhibition of DC-STAMP expression, leading to activation of the DC-STAMP promoter by microphthalmia-associated transcription factor (MITF). Thus, Sbno2 plays a pivotal role in bone homeostasis in vivo by fine-tuning osteoclast fusion.
Distribution of Lettuce Big-Vein Incidence Under Three Irrigation Systems
Authors: Hao J. J. , Subbarao K. V.
Published: August 2013

Spatial patterns of lettuce big-vein (LBV) incidence under furrow, sprinkler, and subsurface drip irrigation systems were determined. Because LBV pathogen is a virus and is vectored by the soilborne chytrid Olpidium brassicae, different irrigation systems likely affect the movement of the vector and were hypothesized to result in different distribution patterns and levels of the disease. Lettuce plants were mapped by recording the location of each LBV-infected or healthy plant in arbitrarily selected plots of sizes 16 by 30, 20 by 30, and 18 by 50 m in Salinas, Gonzales, and Santa Maria in California. Data were arrayed into different quadrat sizes by rearrangement, and disease incidence was calculated for each quadrat. Frequency distribution analysis and spatial autocorrelation analyses were performed on this data. LBV incidence was aggregated in all furrow-irrigated fields, four of five subsurface drip-irrigated fields, and two of three sprinkler-irrigated fields. The remaining fields had a random distribution. As the quadrat size increased, index of aggregation decreased, and vice versa. In fields under sprinkler irrigation, regardless of whether the spatial pattern of LBV was random or aggregated, no directional orientation occurred. However, under furrow or subsurface drip irrigation, the aggregation mostly occurred across the rows. Although irrigation type influenced LBV distribution pattern and incidence in lettuce fields, the differential effects of irrigation type on vector O. brassicae could not be discerned in this study. The sprinkler irrigation practiced in lettuce production until thinning may influence the vector distribution and the subsequent irrigation methods adapted for the remainder of the season in individual fields may play a significant role in disease incidence.
Moderate Hyperventilation during Intravenous Anesthesia Increases Net Cerebral Lactate Efflux
Authors: Grüne Frank , Kazmaier Stephan , Sonntag Hans , Stolker Robert Jan , Weyland Andreas
Published: August 2013

Background:

Hyperventilation is known to decrease cerebral blood flow (CBF) and to impair cerebral metabolism, but the threshold in patients undergoing intravenous anesthesia is unknown. The authors hypothesized that reduced CBF associated with moderate hyperventilation might impair cerebral aerobic metabolism in patients undergoing intravenous anesthesia.

Methods:

Thirty male patients scheduled for coronary surgery were included in a prospective, controlled crossover trial. Measurements were performed under fentanyl-midazolam anesthesia in a randomized sequence aiming at partial pressures of carbon dioxide of 30 and 50 mmHg. Endpoints were CBF, blood flow velocity in the middle cerebral artery, and cerebral metabolic rates for oxygen, glucose, and lactate. Global CBF was measured using a modified Kety–Schmidt technique with argon as inert gas tracer. CBF velocity of the middle cerebral artery was recorded by transcranial Doppler sonography. Data were presented as mean (SD). Two-sided paired t tests and one-way ANOVA for repeated measures were used for statistical analysis.

Results:

Moderate hyperventilation significantly decreased CBF by 60%, blood flow velocity by 41%, cerebral oxygen delivery by 58%, and partial pressure of oxygen of the jugular venous bulb by 45%. Cerebral metabolic rates for oxygen and glucose remained unchanged; however, net cerebral lactate efflux significantly increased from −0.38 (2.18) to −2.41(2.43) µmol min−1 100 g−1.

Conclusions:

Moderate hyperventilation, when compared with moderate hypoventilation, in patients with cardiovascular disease undergoing intravenous anesthesia increased net cerebral lactate efflux and markedly reduced CBF and partial pressure of oxygen of the jugular venous bulb, suggesting partial impairment of cerebral aerobic metabolism at clinically relevant levels of hypocapnia.
Short- and long-term conditioning of a temperate marine diatom community to acidification and warming
Authors: Tatters Avery O. , Roleda Michael Y. , Schnetzer Astrid , Fu Feixue , Hurd Catriona L. , Boyd Philip W. , Caron David A. , Lie Alle A. Y. , Hoffmann Linn J. , Hutchins David A.
Published: August 2013

Ocean acidification and greenhouse warming will interactively influence competitive success of key phytoplankton groups such as diatoms, but how long-term responses to global change will affect community structure is unknown. We incubated a mixed natural diatom community from coastal New Zealand waters in a short-term (two-week) incubation experiment using a factorial matrix of warming and/or elevated
p
CO
2
and measured effects on community structure. We then isolated the dominant diatoms in clonal cultures and conditioned them for 1 year under the same temperature and
p
CO
2
conditions from which they were isolated, in order to allow for extended selection or acclimation by these abiotic environmental change factors in the absence of interspecific interactions. These conditioned isolates were then recombined into ‘artificial’ communities modelled after the original natural assemblage and allowed to compete under conditions identical to those in the short-term natural community experiment. In general, the resulting structure of both the unconditioned natural community and conditioned ‘artificial’ community experiments was similar, despite differences such as the loss of two species in the latter.
p
CO
2
and temperature had both individual and interactive effects on community structure, but temperature was more influential, as warming significantly reduced species richness. In this case, our short-term manipulative experiment with a mixed natural assemblage spanning weeks served as a reasonable proxy to predict the effects of global change forcing on diatom community structure after the component species were conditioned in isolation over an extended timescale. Future studies will be required to assess whether or not this is also the case for other types of algal communities from other marine regimes.
The stunting effect of a high CO2ocean on calcification and development in sea urchin larvae, a synthesis from the tropics to the poles
Authors: Byrne Maria , Lamare Miles , Winter David , Dworjanyn Symon A. , Uthicke Sven
Published: August 2013

The stunting effect of ocean acidification on development of calcifying invertebrate larvae has emerged as a significant effect of global change. We assessed the arm growth response of sea urchin echinoplutei, here used as a proxy of larval calcification, to increased seawater acidity/pCO2and decreased carbonate mineral saturation in a global synthesis of data from 15 species. Phylogenetic relatedness did not influence the observed patterns. Regardless of habitat or latitude, ocean acidification impedes larval growth with a negative relationship between arm length and increased acidity/pCO2and decreased carbonate mineral saturation. In multiple linear regression models incorporating these highly correlated parameters,pCO2exerted the greatest influence on decreased arm growth in the global dataset and also in the data subsets for polar and subtidal species. Thus, reduced growth appears largely driven by organism hypercapnia. For tropical species, decreased carbonate mineral saturation was most important. No single parameter played a dominant role in arm size reduction in the temperate species. For intertidal species, the models were equivocal. Levels of acidification causing a significant (approx. 10–20+%) reduction in arm growth varied between species. In 13 species, reduction in length of arms and supporting skeletal rods was evident in larvae reared in near-future (pCO2800+ µatm) conditions, whereas greater acidification (pCO21000+ µatm) reduced growth in all species. Although multi-stressor studies are few, when temperature is added to the stressor mix, near-future warming can reduce the negative effect of acidification on larval growth. Broadly speaking, responses of larvae from across world regions showed similar trends despite disparate phylogeny, environments and ecology. Larval success may be the bottleneck for species success with flow-on effects for sea urchin populations and marine ecosystems.