bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of particles attachment to multi-sized dust grains present in electrostatic sheaths of discharge plasmas
Authors: Zaham B. , Tahraoui A. , Benlemdjaldi D. , Chekour S.
Published: December 2014

The loss of electrons and ions due to their attachment to a Gauss-distributed sizes of dust grains present in electrostatic sheaths of discharge plasmas is investigated. A uni-dimensional, unmagnetized, and stationary multi-fluid model is proposed. Forces acting on the dust grain along with its charge are self-consistently calculated, within the limits of the orbit motion limited model. The dynamic analysis of dust grains shows that the contribution of the neutral drag force in the net force acting on the dust grain is negligible, whereas the contribution of the gravity force is found considerable only for micrometer particles. The dust grains trapping is only possible when the electrostatic force is balanced by the ion drag and the gravity forces. This trapping occurs for a limited radius interval of micrometer dust grains, which is around the most probable dust grain radius. The effect of electron temperature and ion density at the sheath edge is also discussed. It is shown that the attachment of particles reduces considerably the sheath thickness and induces dust grain deceleration. The increase of the lower limit as well as the upper limit of the dust radius reduces also the sheath thickness.
Molybdenum oxide MoOx: A versatile hole contact for silicon solar cells
Authors: Bullock James , Cuevas Andres , Allen Thomas , Battaglia Corsin
Published: December 2014

This letter examines the application of transparent MoOx (x < 3) films deposited by thermal evaporation directly onto crystalline silicon (c-Si) to create hole-conducting contacts for silicon solar cells. The carrier-selectivity of MoOx based contacts on both n- and p-type surfaces is evaluated via simultaneous consideration of the contact recombination parameter J0c and the contact resistivity ρc. Contacts made to p-type wafers and p+ diffused regions achieve optimum ρc values of 1 and 0.2 mΩ·cm2, respectively, and both result in a J0c of ∼200 fA/cm2. These values suggest that significant gains can be made over conventional hole contacts to p-type material. Similar MoOx contacts made to n-type silicon result in higher J0c and ρc with optimum values of ∼300 fA/cm2 and 30 mΩ·cm2 but still offer significant advantages over conventional approaches in terms of contact passivation, optical properties, and device fabrication.
Three layers of skyrmions in the magnetic triple-layer structure without the Dzyaloshinsky-Moriya interaction
Authors: Xie Kaixuan , Sang Hai
Published: December 2014

The skyrmionic state is an exciting realm of study and the skyrmions are being explored as the promising candidates of information carriers. In most systems, the skyrmions originate from the Dzyaloshinsky–Moriya interaction (DMI). However, in this work, it is demonstrated that in the triple-layer CoPt/Co/CoPt structure, the skyrmion-like state can be formed not only in the CoPt layers but also in the middle Co layer, without DMI. In this new structure, the skyrmion-like state in Co layer can exist in a large CoPt thickness range with thick Co. It can be very stable even against the external field from −500 to 200 mT along Z axis. The skyrmion number (S) in Co (SCo) can be as large as 0.9. These advanced properties make it high application potential for the future information-processing and storage devices.
Communication: Time- and space-sliced velocity map electron imaging
Authors: Lee Suk Kyoung , Lin Yun Fei , Lingenfelter Steven , Fan Lin , Winney Alexander H. , Li Wen
Published: December 2014

We develop a new method to achieve slice electron imaging using a conventional velocity map imaging apparatus with two additional components: a fast frame complementary metal-oxide semiconductor camera and a high-speed digitizer. The setup was previously shown to be capable of 3D detection and coincidence measurements of ions. Here, we show that when this method is applied to electron imaging, a time slice of 32 ps and a spatial slice of less than 1 mm thick can be achieved. Each slice directly extracts 3D velocity distributions of electrons and provides electron velocity distributions that are impossible or difficult to obtain with a standard 2D imaging electron detector.
The effect of the hole injection layer on the performance of single layer organic light-emitting diodes
Authors: Wenjin Zeng , Ran Bi , Hongmei Zhang , Wei Huang
Published: December 2014

Efficient single-layer organic light-emitting diodes (OLEDs) were reported based on a green fluorescent dye 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7–tetramethyl-1H,5H,11H-(1) benzopyropyrano (6,7-8-I,j)quinolizin-11-one (C545T). Herein, poly(3,4-ethylenedioxy thiophene) poly(styrene sulfonate) were, respectively, applied as the injection layer for comparison. The hole transport properties of the emission layer with different hole injection materials are well investigated via current-voltage measurement. It was clearly found that the hole injection layers (HILs) play an important role in the adjustment of the electron/hole injection to attain transport balance of charge carriers in the single emission layer of OLEDs with electron-transporting host. The layer of tris-(8-hydroxyquinoline) aluminum played a dual role of host and electron-transporting materials within the emission layer. Therefore, appropriate selection of hole injection layer is a key factor to achieve high efficiency OLEDs with single emission layer.
Physical deoxygenation of graphene oxide paper surface and facile in situ synthesis of graphene based ZnO films
Authors: Ding Jijun , Wang Minqiang , Zhang Xiangyu , Ran Chenxin , Shao Jinyou , Ding Yucheng
Published: December 2014

In-situ sputtering ZnO films on graphene oxide (GO) paper are used to fabricate graphene based ZnO films. Crystal structure and surface chemical states are investigated. Results indicated that GO paper can be effectively deoxygenated by in-situ sputtering ZnO on them without adding any reducing agent. Based on the principle of radio frequency magnetron sputtering, we propose that during magnetron sputtering process, plasma streams contain large numbers of electrons. These electrons not only collide with argon atoms to produce secondary electrons but also they are accelerated to bombard the substrates (GO paper) resulting in effective deoxygenation of oxygen-containing functional groups. In-situ sputtering ZnO films on GO paper provide an approach to design graphene-semiconductor nanocomposites.
Ultrafast free-carrier dynamics in Cu2ZnSnS4 single crystals studied using femtosecond time-resolved optical spectroscopy
Authors: Phuong L. Q. , Okano M. , Yamada Y. , Yamashita G. , Morimoto T. , Nagai M. , Ashida M. , Nagaoka A. , Yoshino K. , Kanemitsu Y.
Published: December 2014

We studied the dynamics of photogenerated carriers in Cu2ZnSnS4 (CZTS) single crystals using femtosecond transient reflectivity (TR) and optical pump-THz probe transient absorption (THz-TA) spectroscopy. The TR and THz-TA decay dynamics consistently showed that free carriers have long lifetimes of up to a few nanoseconds. The excitation-photon-energy-dependent TR measurements revealed a slow picosecond energy relaxation of free carriers to the band edge in CZTS. The relaxation and recombination dynamics of free carriers were affected by nonradiative recombinations at the surface. Our results revealed a global feature of energy relaxation and recombination processes of free carriers in CZTS single crystals.
Oscillating magnetocaloric effect of a multilayer graphene
Authors: Alisultanov Z. Z. , Paixão L. S. , Reis M. S.
Published: December 2014

The oscillating magnetocaloric effect of a multilayer graphene in Bernal and rhombohedral stacking is investigated to extend the previous knowledge of the effect on a single layer graphene. We started from results of a tight-binding model and obtained analytical expressions for the thermodynamic potential and for the entropy change. The last exhibits the same dependence on field and temperature observed for other diamagnetic systems; it oscillates with the inverse magnetic field and presents a maximum value at a given temperature. The amplitude of the oscillating entropy change decreases with the number of layers and the stacking sequence rules the magnetocaloric properties of the system.
High-power narrow-vertical-divergence photonic band crystal laser diodes with optimized epitaxial structure
Authors: Liu Lei , Qu Hongwei , Liu Yun , Zhang Yejin , Wang Yufei , Qi Aiyi , Zheng Wanhua
Published: December 2014

900 nm longitudinal photonic band crystal (PBC) laser diodes with optimized epitaxial structure are fabricated. With a same calculated fundamental-mode divergence, stronger mode discrimination is achieved by a quasi-periodic index modulation in the PBC waveguide than a periodic one. Experiments show that the introduction of over 5.5 μm-thick PBC waveguide contributes to only 10% increment of the internal loss for the laser diodes. For broad area PBC lasers, output powers of 5.75 W under continuous wave test and over 10 W under quasi-continuous wave test are reported. The vertical divergence angles are 10.5° at full width at half maximum and 21.3° with 95% power content, in conformity with the simulated angles. Such device shows a prospect for high-power narrow-vertical-divergence laser emission from single diode laser and laser bar.
Linear and nonlinear effect of sheared plasma flow on resistive tearing modes
Authors: Hu Qiming , Yu Q. , Hu Xiwei
Published: December 2014

The effect of sheared plasma flow on the m/n = 2/1 tearing mode is studied numerically (m and n are the poloidal and toroidal mode numbers). It is found that in the linear phase the plasma flow with a weak or moderate shear plays a stabilizing effect on tearing mode. However, the mode is driven to be more unstable by sufficiently strong sheared flow when approaching the shear Alfvén resonance (AR). In the nonlinear phase, a moderate (strong) sheared flow leads to a smaller (larger) saturated island width. The stabilization of tearing modes by moderate shear plasma flow is enhanced for a larger plasma viscosity and a lower Alfvén velocity. It is also found that in the nonlinear phase AR accelerates the plasma rotation around the 2/1 rational surface but decelerates it at the AR location, and the radial location satisfying AR spreads inwards towards the magnetic axis.
The growth of heteroepitaxial CuInSe2 on free-standing N-polar GaN
Authors: Shih Cheng-Hung , Lo Ikai , You Shuo-Ting , Tsai Cheng-Da , Tseng Bae-Heng , Chen Yun-Feng , Chen Chiao-Hsin , Lee Chuo-Han , Lee Wei-I , Hsu Gary Z. L.
Published: December 2014

We report that chalcopyrite CuInSe2 thin films were grown on free-standing N-polar GaN (0001̄) by molecular beam epitaxy. X-ray diffraction showed that the CuInSe2 thin film was grown in (112) orientation, and its peak of rocking curve with full width at half maximum of about 897.8 arc-sec indicated the epitaxial growth of CuInSe2 (112) film on N-polar GaN. Microstructure analysis of the CuInSe2  showed that the large lattice mismatch (28.5%) between CuInSe2  and GaN is accommodated by domain matching, and no interface reaction occurs between CuInSe2 and GaN. Our experimental results show that GaN is stable for the epitaxial growth of CuInSe2 thin film, which exhibits a promising potential for optoelectronic applications.
Thermal transport in 2- and 3-dimensional periodic “holey” nanostructures
Authors: Ma J. , Sadhu J. S. , Ganta D. , Tian H. , Sinha S.
Published: December 2014

Understanding thermal transport in two- and three-dimensional periodic “holey” nanostructures is important for realizing applications of these structures in thermoelectrics, photonics and batteries. In terms of continuum heat diffusion physics, the effective medium theory provides the framework for obtaining the effective thermal conductivity of such structures. However, recently measured nanostructures possess thermal conductivities well below these continuum predictions. In some cases, their thermal conductivities are even lower than predictions that account for sub-continuum phonon transport. We analyze current understanding of thermal transport in such structures, discussing the various theories, the measurements and the insights gained from comparing the two.
Photoresponsive properties of ultrathin silicon nanowires
Authors: Tran Duy P. , Macdonald Thomas J. , Wolfrum Bernhard , Stockmann Regina , Nann Thomas , Offenhäusser Andreas , Thierry Benjamin
Published: December 2014

Functional silicon nanowires (SiNWs) are promising building blocks in the design of highly sensitive photodetectors and bio-chemical sensors. We systematically investigate the photoresponse properties of ultrathin SiNWs (20 nm) fabricated using a size-reduction method based on e-beam lithography and tetramethylammonium hydroxide wet-etching. The high-quality SiNWs were able to detect light from the UV to the visible range with excellent sensitivity (∼1 pW/array), good time response, and high photoresponsivity (R ∼ 2.5 × 104 A/W). Improvement of the ultrathin SiNWs' photoresponse has been observed in comparison to 40 nm counter-part nanowires. These properties are attributable to the predominance surface-effect due to the high surface-to-volume ratio of ultrathin SiNWs. Long-term measurements at different temperatures in both the forward and reverse bias directions demonstrated the stability and reliability of the fabricated device. By sensitizing the fabricated SiNW arrays with cadmium telluride quantum dots (QDs), hybrid QD SiNW devices displayed an improvement in photocurrent response under UV light, while preserving their performance in the visible light range. The fast, stable, and high photoresponse of these hybrid nanostructures is promising towards the development of optoelectronic and photovoltaic devices.
Prolonging Life: Appreciations of a Secondhand ‘Capital’ Machine
Authors: Spiller Keith
Published: December 2014

In this paper I look at a farm that diversified its business and within this process bought a secondhand sausage vacuum filler. I do this in order to question how this machine came to be understood and valued by the farmers who bought it. The themes discussed include the role of the machine in changing the working practices of the farm, as well as factors unknown when buying secondhand—purchasers can only ever truly know the reliability and levels of performance of the machine retrospectively. While much work has considered the secondhand cultures of goods such as clothes, brick-a-brac, or cars, the departure I make here is to consider goods bought and used in commercial contexts. I consider the calculations made when a secondhand commodity is invested with the risks and tensions of expanding a business. There are critical and additional pressures resting on the machine: for example, if the machine fails to work, it may be detrimental to the business. The paper focuses on the appreciations of two farmers and how the machine they bought was used and appreciated.
Moving Considerations of Middle-Class Residents in Dutch Disadvantaged Neighborhoods: Exploring the Relationship between Disorder and Attachment
Authors: Pinkster Fenne M , Permentier Matthieu , Wittebrood Karin
Published: December 2014

A central assumption in the residential mobility literature is that residents in disadvantaged neighborhoods will leave as soon as they are financially able, as a result of ‘residential stress’ related to physical and social disorder in these neighborhoods. However, this assumption contradicts the continuing presence of a substantial share of middle-class residents in disadvantaged urban neighborhoods in the Netherlands. A qualitative study amongst middle-class residents in disadvantaged areas in Amsterdam and The Hague explored whether and how the residential context plays a role in their decision-making process about moving, focusing particularly on the way in which perceptions of neighborhood disorder on the one hand and processes of neighborhood attachment on the other shape moving decisions. In contrast to what was expected based on the research literature, perceptions of neighborhood disorder do not ‘push’ people out and positive ties to the neighborhood do not keep people there. Rather, a lack of attachment seems to ‘shield’ residents from neighborhood disorder and reduces their propensity to move out.
Urban Growth Boundaries and their Impact on Land Prices
Authors: Ball Michael , Cigdem Melek , Taylor Elizabeth , Wood Gavin
Published: December 2014

Undeveloped land transactions at the urban fringe of the Melbourne metropolitan area in Australia are recorded in a dataset that enables exploration of the impact of its urban growth boundary (UGB) on residential land prices. Estimation can take account of a wide range of factors, while controlling for policy anticipation effects and other potential influences on land prices. Modelling estimates indicate that land prices rose substantially inside the UGB after its enactment in 2003, but did not rise much outside of it. These results suggest that the urban growth boundary has had a significant upward effect on the trajectory of the urban region's house prices.
Understanding the Governance of Corporations: An Examination of the Factors Shaping UK Supermarket Strategies on Climate Change
Authors: Gouldson Andy , Sullivan Rory
Published: December 2014

This paper starts from the premise that our understanding of the extent to which, and of the conditions under which, we might rely on new or neoliberal forms of governance beyond the state to deliver particular public interest objectives is limited, especially when they seek to instigate changes in corporate behaviour. In response, we briefly explore some of the key elements of debates on ‘governance from the outside’ where public, private, and civic actors engage in activities that seek to shape the behaviour or performance of a corporation, and ‘governance from the inside’ where the behaviour of a corporation is shaped by, for example, its structures and systems, resources and opportunities, and cultures and values. We hypothesise that the ability of a particular set of governance conditions to change the behaviour or performance of a business will be shaped by the strength and alignment of (a) the range of external governance pressures surrounding the business and (b) the internal governance conditions within that business. We then consider the reasons why firms within one key sector (UK supermarkets) have responded to one key issue (climate change) in recent years. We argue that a specific set of governance conditions brought about a step change in UK supermarkets' approach to climate change in 2007/08, and that this has triggered a period of improvement in their climate-related performance. However, we suggest that this process of improvement is bounded by the presence of a business case that simultaneously supports incremental change and constrains the potential for more transformative change. We conclude by suggesting that if the business case weakens, then governance conditions are likely to be characterised either by collective inaction or by socially led governance, with its influence being determined by whether the diverse forms of social pressure that are central to it are stronger and better aligned than any associated forms of business resistance. We argue that this has significant implications for our understanding of the extent to which new or neoliberal forms of governance beyond the state can be relied upon to ensure that corporations—or indeed other actors—might help to deliver public interest objectives.
The Geography of Chinese Science
Authors: Andersson David Emanuel , Gunessee Saileshsingh , Matthiessen Christian Wichmann , Find Søren
Published: December 2014

Chinese scientific output has increased dramatically in recent years, but its internal spatial structure has received scant attention. Estimated gravity models of intercity scientific coauthorships show that there are two types of spatial political bias in China, apart from the expected mass and distance effects. Intercity coauthorships involving Beijing are more common than Beijing's output volume and location would imply, and this Beijing bias is increasing over time. The second type of spatial political bias is greater intraprovincial collaboration than is accounted for by size and distance. The geography of Chinese science is thus not only monocentric as regards overall scientific output, but also exhibits unusually hierarchical collaboration patterns. Unlike in Europe and North America, national and regional capitals are becoming ever more important as scientific coordination centers.
Citizenshit: The Right to Flush and the Urban Sanitation Imaginary
Authors: Morales Margaret del Carmen , Harris Leila , Öberg Gunilla
Published: December 2014

For many in the Global North, urban life means that your shit is not your problem. We postulate that a possible reason for the global sanitation failure in urban areas is a disconnect between sanitation expectations—what we term the urban sanitation imaginary—and the practices required by proposed sanitation solutions. The case study presented here is based on interviews with residents of Villa Lamadrid, a marginalized neighborhood in Buenos Aires, Argentina, which faces significant public health impacts from an inadequate sewage management system. We solicited feedback regarding specific sanitation technologies frequently prescribed for poor urban communities—among them a urine diversion dry toilet with dehydration vaults. Even as this system is posited as ‘sustainable’ for the context of Villa Lamadrid in terms of ecological and economic factors, conversations with residents revealed why this option might not be sustainable in terms of social expectations. On the basis of interviews with community members we have defined four aspects of residents' urban sanitation imaginaries that we consider highly relevant for any consideration of sanitation solutions in this context: (1) an urban citizen does not engage physically or mentally with their shit or its management; (2) an appropriate urban sanitation system requires flushing; (3) systems that require user's engagement with their shit and its management signify rural, underdeveloped, and backward lifestyles; and (4) urban sanitation is a state responsibility, not a local one. Highlighting the urban sanitation imaginary methodologically and analytically goes beyond a discussion of culturally and contextually appropriate technologies. It examines linkages between user expectations and notions of urban citizenship and modernity. Ultimately it also draws attention to the sociopolitical dynamics and environmental justice issues embedded in discussions of sanitation and hygiene. While some of our results are specific to the Villa Lamadrid context, our research more generally suggests the need to consider sanitation imaginaries to reframe the discussion on sanitation interventions, particularly in underserved and impoverished urban areas.
The Semantics of Biological Forms
Authors: Albertazzi Liliana , Canal Luisa , Dadam James , Micciolo Rocco
Published: December 2014

This study analyses how certain qualitative perceptual appearances of biological forms are correlated with expressions of natural language. Making use of the Osgood semantic differential, we presented the subjects with 32 drawings of biological forms and a list of 10 pairs of connotative adjectives to be put in correlations with them merely by subjective judgments. The principal components analysis made it possible to group the semantics of forms according to two distinct axes of variability: Harmony and dynamicity. Specifically, the nonspiculed, nonholed, and flat forms were perceived as harmonic and static; the rounded ones were harmonic and dynamic. The elongated forms were somewhat disharmonious and somewhat static. The results suggest the existence in the general population of a correspondence between perceptual and semantic processes, and of a nonsymbolic relation between visual forms and their adjectival expressions in natural language.
High-energy chemistry of formamide: A unified mechanism of nucleobase formation
Authors: Ferus Martin , Nesvorný David , Šponer Jiří , Kubelík Petr , Michalčíková Regina , Shestivská Violetta , Šponer Judit E. , Civiš Svatopluk
Published: December 2014

Significance

This paper addresses one of the central problems of the origin of life research, i.e., the scenario suggesting extraterrestrial impact as the source of biogenic molecules. Likewise, the results might be relevant in the search of biogenic molecules in the universe. The work is therefore highly actual and interdisciplinary. It could be interesting for a very broad readership, from physical and organic chemists to synthetic biologists and specialists in astrobiology.
Single-chain protein mimetics of the N-terminal heptad-repeat region of gp41 with potential as anti–HIV-1 drugs
Authors: Crespillo Sara , Cámara-Artigas Ana , Casares Salvador , Morel Bertrand , Cobos Eva S. , Mateo Pedro L. , Mouz Nicolas , Martin Christophe E. , Roger Marie G. , El Habib Raphaelle , Su Bin , Moog Christiane , Conejero-Lara Francisco
Published: December 2014

Significance

The envelope subunit gp41 is an attractive target for therapeutic intervention against HIV-1. Interfering with the interaction between the heptad-repeat regions of gp41 is a promising approach to inhibit HIV-1 fusion to the host cell membrane. Here, we present an alternative rational design and protein-engineering approach to produce highly stable single-chain proteins that accurately mimic the trimeric coiled-coil surface of the gp41 N-terminal heptad repeat. This approach has a strong potential for development to HIV-1 drugs, vaccines, or microbicides and could be extendable to the design of proteins interfering with other types of coiled-coil interactions.
Restoration of visual function by expression of a light-gated mammalian ion channel in retinal ganglion cells or ON-bipolar cells
Authors: Gaub Benjamin M. , Berry Michael H. , Holt Amy E. , Reiner Andreas , Kienzler Michael A. , Dolgova Natalia , Nikonov Sergei , Aguirre Gustavo D. , Beltran William A. , Flannery John G. , Isacoff Ehud Y.
Published: December 2014

Significance

We restored visual function to animal models of human blindness using a chemical compound that photosensitizes a mammalian ion channel. Virus-mediated expression of this light sensor in surviving retinal cells of blind mice restored light responses in vitro, reanimated innate light avoidance, and enabled learned visually guided behavior. The treatment also restored light responses to the retina of blind dogs. Patients that might benefit from this treatment would need to have intact ganglion cell and nerve fiber layers. In general, these are patients diagnosed with retinitis pigmentosa and some forms of Leber congenital amaurosis. Patients diagnosed with other types of blindness, for example, age-related macular degeneration or diabetic retinopathy, would not be candidates for this treatment.
Disruption of the Na
+
ion binding site as a mechanism for positive allosteric modulation of the mu-opioid receptor
Authors: Livingston Kathryn E. , Traynor John R.
Published: December 2014

Significance

Morphine and related compounds are the gold standard for the management of pain. Such drugs bind to the orthosteric site on the mu-opioid receptor (MOPr), a G protein-coupled receptor (GPCR). We have proposed that targeting an allosteric site on MOPr could result in improved pain management and have reported positive allosteric modulators (PAMs) of MOPr. High-resolution X-ray structures have identified a Na
+
binding site on multiple GPCRs and have shown how bound Na
+
stabilizes inactive receptor states. Here we demonstrate that PAM activity at MOPr allosterically disrupts Na
+
binding, thereby forming an active-state receptor. The Na
+
binding site is highly conserved across class A GPCRs so this may represent a fundamental mechanism of allosteric modulation.
Automated analysis of immunohistochemistry images identifies candidate location biomarkers for cancers
Authors: Kumar Aparna , Rao Arvind , Bhavani Santosh , Newberg Justin Y. , Murphy Robert F.
Published: December 2014

Significance

Changes in the expression of proteins are often associated with oncogenesis, and are frequently used as cancer biomarkers. Changes in the subcellular location of proteins have been less frequently investigated. In this paper, we describe a robust pipeline for identifying those proteins whose subcellular location undergoes statistically significant changes in cancers of four tissues, and also for identifying biochemical pathways that are enriched for proteins that translocate. Future investigation of these proteins and pathways may provide new insight into oncogenesis. Further, the analysis pipeline is expected to be useful for assessing disease type and severity in a clinical setting.
Optogenetic activation of GnRH neurons reveals minimal requirements for pulsatile luteinizing hormone secretion
Authors: Campos Pauline , Herbison Allan E.
Published: December 2014

Significance

The mammalian reproductive system is critically dependent upon pulsatile hormone release patterned and driven by a small population of gonadotropin-releasing hormone (GnRH) neurons. The scattered distribution of GnRH neurons within the brain has made it extremely difficult to investigate the nature and properties of these cells in any selective manner in vivo. We report here a procedure that enables selective, high-fidelity activation of the GnRH neurons that control gonadotropin secretion in ovariectomized mice. Using this approach, we have been able to define minimal parameters of activation required to generate pulsatile gonadotropin secretion in the blood. This provides critical information for understanding and manipulating the genesis of gonadotropin pulsatility in reproductive biology.
Host-specific induction of
Escherichia coli
fitness genes during human urinary tract infection
Authors: Subashchandrabose Sargurunathan , Hazen Tracy H. , Brumbaugh Ariel R. , Himpsl Stephanie D. , Smith Sara N. , Ernst Robert D. , Rasko David A. , Mobley Harry L. T.
Published: December 2014

Significance

Escherichia coli
is the most common cause of urinary tract infections (UTI) in humans. This bacterium is a major global public health concern because it is becoming resistant to currently available antibiotics. Therefore, it is imperative to develop new treatment and prevention strategies against this bacterium. However, the processes that promote survival of this bacterium within the human urinary tract during UTI are not clearly understood. Here we identify
E. coli
genes that promote survival within the urinary tract during naturally occurring UTI in women. Genes identified in this study represent targets for development of new therapies against UTI caused by
E. coli
.
A complete Holocene record of trematode–bivalve infection and implications for the response of parasitism to climate change
Authors: Huntley John Warren , Fürsich Franz T. , Alberti Matthias , Hethke Manja , Liu Chunlian
Published: December 2014

Significance

There is growing concern about how parasites will respond to climate change. Previous studies were based on data from short time scales (10
−1
to 10
3
y), but here we present, to our knowledge, the first analysis of the response of parasites to global change on a longer time scale (10
4
y), utilizing the subfossil record. A 9,600-y record of clams and flatworm parasites from the Pearl River Delta exhibits a significant spike in parasite prevalence during the initial phase of sea-level rise. This increase is not related to changes in salinity or intermediate host availability. Temperature and productivity cannot be quantified and tested as driving factors. These results suggest stark implications for macrobenthos, fisheries, and human health in the context of climate change.
Dopamine-associated cached values are not sufficient as the basis for action selection
Authors: Hollon Nick G. , Arnold Monica M. , Gan Jerylin O. , Walton Mark E. , Phillips Paul E. M.
Published: December 2014

Significance

Real-world decisions frequently involve tradeoffs between multiple economic dimensions, and integration of benefits and costs into a common currency of subjective value is fundamental to action selection. Phasic dopamine is widely regarded as a critical teaching signal for learning the values assigned to actions, and these stored (“cached”) values can be read out from cue-evoked dopamine responses. Here, we observed a significant inversion between animals’ behavioral preferences and the rank ordering of dopamine-reported cached values, indicating that these cached values cannot be the sole determinant of choices in simple economic decision making. These data challenge the fundamental tenet of contemporary theories of decision making which posit that dopamine-associated cached values are sufficient to serve as the basis for action selection.
Dual-specificity phosphatase 5 regulates nuclear ERK activity and suppresses skin cancer by inhibiting mutant Harvey-Ras (HRas
Q61L
)-driven SerpinB2 expression
Authors: Rushworth Linda K. , Kidger Andrew M. , Delavaine Laurent , Stewart Graeme , van Schelven Susanne , Davidson Jane , Bryant Christopher J. , Caddye Edward , East Philip , Caunt Christopher J. , Keyse Stephen M.
Published: December 2014

Significance

Ras/extracellular signal-regulated kinase (ERK) signaling is implicated in human cancer development and progression. ERK activation also results in the expression of MAP kinase phosphatases (MKPs) that inactivate ERK. However, it is currently unclear how MKPs regulate the oncogenic potential of the Ras/ERK pathway. Using knockout mice, we identify the MKP encoded by dual-specificity phosphatase 5 (DUSP5) as both a key regulator of nuclear ERK activity and a tumor suppressor in the DMBA/TPA model of Harvey Ras (HRas)-induced skin carcinogenesis. DUSP5 loss results in increased HRas/ERK-inducible SerpinB2 expression, which causes increased skin cancer sensitivity. Our results establish a key role for DUSP5 in the regulation of oncogenic ERK signaling and suggest that this enzyme may play a wider role in tumors containing activated Ras.
A partial hominoid innominate from the Miocene of Pakistan: Description and preliminary analyses
Authors: Morgan Michèle E. , Lewton Kristi L. , Kelley Jay , Otárola-Castillo Erik , Barry John C. , Flynn Lawrence J. , Pilbeam David
Published: December 2014

Significance

The living apes share a number of important morphological similarities of torso and limbs; torsos are broad and shallow, lumbar regions short, and forelimbs adapted to mobility. For more than a century it was assumed that most of these similarities are homologous, reflecting descent from a common ancestor with these features. As the ape fossil record slowly expands, the story becomes more complicated, particularly in the case of the south Asian Miocene apeSivapithecus.Sivapithecushas facial features resembling specifically the living orangutan, but no postcranial features resembling orangutans. This newly described hipbone differs from that of all living apes. Either postcranial similarities of apes are not fully homologous or the facial similarities ofSivapithecusand orangutans cannot be homologous.
Endogenous cannabinoid release within prefrontal-limbic pathways affects memory consolidation of emotional training
Authors: Morena Maria , Roozendaal Benno , Trezza Viviana , Ratano Patrizia , Peloso Andrea , Hauer Daniela , Atsak Piray , Trabace Luigia , Cuomo Vincenzo , McGaugh James L. , Schelling Gustav , Campolongo Patrizia
Published: December 2014

Significance

An involvement of exogenous cannabinoids in the regulation of memory for emotional events has emerged over the past decade. The present findings demonstrate that after an aversive training experience the endogenous cannabinoid anandamide is released into the amygdala, hippocampus, and medial prefrontal cortex (mPFC) and normally plays a role in the formation of a strong memory trace. Furthermore, an intact basolateral amygdala is required to coordinate both hippocampal and mPFC endocannabinoid activity during aversive memory consolidation. Thus, our findings provide the first evidence, to our knowledge, that a dynamic network involving anandamide signaling within this prefrontal-limbic circuit modulates the consolidation of memory for emotionally arousing training.
Preassociated apocalmodulin mediates Ca
2+
-dependent sensitization of activation and inactivation of TMEM16A/16B Ca
2+
-gated Cl
−
channels
Authors: Yang Tingting , Hendrickson Wayne A. , Colecraft Henry M.
Published: December 2014

Significance

Calcium-activated chloride channels (CaCCs) encoded by transmembrane members 16A and 16B (TMEM16A/16B) are vital for physiological functions ranging from smooth muscle contraction to cell proliferation and are important therapeutic targets. Here, applying a recently developed bioengineering approach referred to as channel inactivation induced by membrane tethering of an associated protein (ChIMP), we found that the Ca
2+
-sensing protein calmodulin (CaM) is preassociated with TMEM16A/16B channel complexes in its Ca
2+
-free state (apoCaM). The preassociated apoCaM acts as a resident Ca
2+
sensor that increases Ca
2+
sensitivity of TMEM16A/16B activation at low intracellular Ca
2+
concentrations and also mediates inactivation of TMEM16A channels at high Ca
2+
concentrations. The results reveal a previously unidentified role for apoCaM in Ca
2+
-dependent regulation of TMEM16A/16B channels that is likely physiologically important, and may be a promising site to target for therapy.
Place cells in the hippocampus: Eleven maps for eleven rooms
Authors: Alme Charlotte B. , Miao Chenglin , Jezek Karel , Treves Alessandro , Moser Edvard I. , Moser May-Britt
Published: December 2014

Significance

The hippocampus is thought to store a large number of experiences that, despite their similarity, can be individually retrieved with minimal interference. Studies have shown that place cells in hippocampal area CA3 form statistically independent representations of pairs of environments. It has remained unclear, however, whether CA3 place cells maintain this independence when the number of environments is increased. We recorded activity from CA3 in 11 environments with nearly identical geometric features. Spatial firing patterns remained uncorrelated across all 55 pairs of environments, with minimal overlap in the populations of active cells. The data suggest that the capacity of the CA3 network is large and speak against extensive recurrence of spatial motifs across experiences.
Real-time monitoring of quorum sensing in 3D-printed bacterial aggregates using scanning electrochemical microscopy
Authors: Connell Jodi L. , Kim Jiyeon , Shear Jason B. , Bard Allen J. , Whiteley Marvin
Published: December 2014

Significance

Bacteria commonly reside in vivo as communities comprised of small, densely packed aggregates. Aggregates display important phenotypes, including enhanced antibiotic resistance, and recent evidence suggests that chemical interactions between aggregates are critical in human-associated microbial communities. However, studying aggregates is challenging because of the inability to confine and spatially organize small microbial populations. Here, we interface two analytical technologies, micro-3D printing and scanning electrochemical microscopy, to develop an in vitro platform with the capacity to manipulate the size and spatial arrangement of bacterial aggregates and quantify chemical interactions between aggregates in real time. We show that a quorum-sensing metabolite is produced by
Pseudomonas aeruginosa
aggregates containing as few as 500 cells and determine how spatial structure impacts communication between neighboring aggregates.
HSP90 empowers evolution of resistance to hormonal therapy in human breast cancer models
Authors: Whitesell Luke , Santagata Sandro , Mendillo Marc L. , Lin Nancy U. , Proia David A. , Lindquist Susan
Published: December 2014

Significance

Although hormonal therapies for estrogen receptor-positive (ER+) breast cancer make up the earliest, and arguably most effective, “molecularly targeted” anticancer drugs, continued progress in controlling metastatic disease has been slow. Heterogeneity and the complexity of signaling in advanced cancers have frustrated efforts to prevent the rapid evolution of resistance to hormonal therapies, as well as kinase inhibitors and other agents. On the basis of earlier work defining the role of heat shock protein 90 (HSP90) in other evolutionary processes, we tested whether low-level HSP90 inhibition would limit the evolution of hormone resistance in breast cancer models. Results in culture and in mice provide support for a readily implemented strategy by which the heterogeneity and evolvability of metastatic ER+ breast tumors, and perhaps other advanced cancers, might be controlled.
Cortical plasticity induced by transplantation of embryonic somatostatin or parvalbumin interneurons
Authors: Tang Yunshuo , Stryker Michael P. , Alvarez-Buylla Arturo , Espinosa Juan Sebastian
Published: December 2014

Significance

The cerebral cortex contains two major types of interneurons that are implicated in epilepsy and neurodegenerative diseases. Here we determined their role in the induction of critical period plasticity, a form of circuit modification essential for brain maturation and repair. Surprisingly, transplantation of either cell type was sufficient to induce critical period plasticity. The work provides insight into the cellular mechanisms that shape brain circuits during key periods of development and defines populations of inhibitory nerve cells sufficient to induce plastic changes that could help in the treatment of brain diseases.
Dynamic changes in E-protein activity regulate T reg cell development
Authors: Gao Ping , Han Xiaojuan , Zhang Qi , Yang Zhiqiong , Fuss Ivan J. , Myers Timothy G. , Gardina Paul J. , Zhang Fuping , Strober Warren
Published: December 2014

E-proteins are TCR-sensitive transcription factors essential for intrathymic T cell transitions. Here, we show that deletion of E-proteins leads to both enhanced peripheral TGF-β–induced regulatory T (iT reg) cell and thymic naturally arising T reg cell (nT reg cell) differentiation. In contrast, deletion of Id proteins results in reduced nT reg cell differentiation. Mechanistic analysis indicated that decreased E-protein activity leads to de-repression of signaling pathways that are essential to Foxp3 expression. Decreased E-protein binding to an IL-2Rα enhancer locus facilitated TCR-induced IL-2Rα expression. Similarly, decreased E-protein activity facilitated TCR-induced NF-κB activation and generation of c-Rel. Consistent with this, microarray analysis indicated that cells with E-protein depletion that are not yet expressing Foxp3 exhibit activation of the IL-2 and NF-κB signaling pathways as well as enhanced expression of many of the genes associated with Foxp3 induction. Finally, studies using Nur77-GFP mice to monitor TCR signaling showed that TCR signaling strength sufficient to induce Foxp3 differentiation is accompanied by down-regulation of E-protein levels. Collectively, these data suggest that TCR stimulation acts in part through down-regulation of E-protein activity to induce T reg cell lineage development.
Gain-of-function CCR4 mutations in adult T cell leukemia/lymphoma
Authors: Nakagawa Masao , Schmitz Roland , Xiao Wenming , Goldman Carolyn K. , Xu Weihong , Yang Yandan , Yu Xin , Waldmann Thomas A. , Staudt Louis M.
Published: December 2014

Adult T cell leukemia/lymphoma (ATLL) is an aggressive malignancy caused by human T cell lymphotropic virus type-I (HTLV-I) without curative treatment at present. To illuminate the pathogenesis of ATLL we performed whole transcriptome sequencing of purified ATLL patient samples and discovered recurrent somatic mutations in CCR4, encoding CC chemokine receptor 4. CCR4 mutations were detected in 14/53 ATLL samples (26%) and consisted exclusively of nonsense or frameshift mutations that truncated the coding region at C329, Q330, or Y331 in the carboxy terminus. Functionally, the CCR4-Q330 nonsense isoform was gain-of-function because it increased cell migration toward the CCR4 ligands CCL17 and CCL22, in part by impairing receptor internalization. This mutant enhanced PI(3) kinase/AKT activation after receptor engagement by CCL22 in ATLL cells and conferred a growth advantage in long-term in vitro cultures. These findings implicate somatic gain-of-function CCR4 mutations in the pathogenesis of ATLL and suggest that inhibition of CCR4 signaling might have therapeutic potential in this refractory malignancy.
Heterozygous splice mutation in PIK3R1 causes human immunodeficiency with lymphoproliferation due to dominant activation of PI3K
Authors: Lucas Carrie L. , Zhang Yu , Venida Anthony , Wang Ying , Hughes Jason , McElwee Joshua , Butrick Morgan , Matthews Helen , Price Susan , Biancalana Matthew , Wang Xiaochuan , Richards Michael , Pozos Tamara , Barlan Isil , Ozen Ahmet , Rao V. Koneti , Su Helen C. , Lenardo Michael J.
Published: December 2014

Class IA phosphatidylinositol 3-kinases (PI3K), which generate PIP3 as a signal for cell growth and proliferation, exist as an intracellular complex of a catalytic subunit bound to a regulatory subunit. We and others have previously reported that heterozygous mutations in PIK3CD encoding the p110δ catalytic PI3K subunit cause a unique disorder termed p110δ-activating mutations causing senescent T cells, lymphadenopathy, and immunodeficiency (PASLI) disease. We report four patients from three families with a similar disease who harbor a recently reported heterozygous splice site mutation in PIK3R1, which encodes the p85α, p55α, and p50α regulatory PI3K subunits. These patients suffer from recurrent sinopulmonary infections and lymphoproliferation, exhibit hyperactive PI3K signaling, and have prominent expansion and skewing of peripheral blood CD8+ T cells toward terminally differentiated senescent effector cells with short telomeres. The PIK3R1 splice site mutation causes skipping of an exon, corresponding to loss of amino acid residues 434–475 in the inter-SH2 domain. The mutant p85α protein is expressed at low levels in patient cells and activates PI3K signaling when overexpressed in T cells from healthy subjects due to qualitative and quantitative binding changes in the p85α–p110δ complex and failure of the C-terminal region to properly inhibit p110δ catalytic activity.
Brown representability and the Eilenberg-Watts theorem in homotopical algebra
Authors: Hovey Mark
Published: December 2014

It is well known that every homology functor on the stable homotopy category is representable, so of the form

E

∗

(
X
)
=

π

∗

(
E
∧
X
)

E_{*} (X)=\pi _{*} (E\wedge X)

for some spectrum

E
E

. However, Christensen, Keller, and Neeman (2001) have exhibited simple triangulated categories, such as the derived category of

k
[
x
,
y
]

k[x,y]

for sufficiently large fields

k
k

, for which not every homology functor is representable. In this paper, we show that this failure of Brown representability does not happen on the model category level. That is, we show that a homology theory is representable if and only if it lifts to a well-behaved functor on the model category level. We also show that, for a reasonable model category

M

\mathcal {M}

, every functor that has the same formal properties as a functor of the form

X
↦
X
⊗
E

X\mapsto X\otimes E

for some cofibrant

E
E

is naturally weakly equivalent to a functor of that form. This is closely related to the Eilenberg-Watts theorem in algebra, which proves that every functor with the same formal properties as the tensor product with a fixed object is isomorphic to such a functor.