bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of Cu2ZnSnSe4 solar cells by low-temperature co-evaporation and following selenization
Authors: Gao Chao , Schnabel Thomas , Abzieher Tobias , Ahlswede Erik , Powalla Michael , Hetterich Michael
Published: January 2016

Cu2ZnSnSe4 (CZTSe) thin films are prepared by a two-step method which involves co-evaporation of Cu, Zn, Sn, and Se on molybdenum-coated soda-lime glass at low substrate temperature and a following selenization. Solar cells with efficiencies of up to 6.5% can be achieved. The influence of the selenium deposition rates during co-evaporation and the nitrogen pressure during selenization on the properties of the CZTSe films are investigated. It is found that these two parameters can significantly affect the morphology and crystallinity of the CZTSe films. The possible reasons for the experimental results are discussed.
Laser-induced THz magnetization precession for a tetragonal Heusler-like nearly compensated ferrimagnet
Authors: Mizukami S. , Sugihara A. , Iihama S. , Sasaki Y. , Suzuki K. Z. , Miyazaki T.
Published: January 2016

Laser-induced magnetization precessional dynamics was investigated in epitaxial films of Mn3Ge, which is a tetragonal Heusler-like nearly compensated ferrimagnet. The ferromagnetic resonance (FMR) mode was observed, the precession frequency for which exceeded 0.5 THz and originated from the large magnetic anisotropy field of approximately 200 kOe for this ferrimagnet. The effective damping constant was approximately 0.03. The corresponding effective Landau-Lifshitz constant is approximately 60 Mrad/s and is comparable with those of the similar Mn-Ga materials. The physical mechanisms for the Gilbert damping and for the laser-induced excitation of the FMR mode were also discussed in terms of the spin-orbit-induced damping and the laser-induced ultrafast modulation of the magnetic anisotropy, respectively.
Effect of the C-bridge length on the ultraviolet-resistance of oxycarbosilane low-k films
Authors: Redzheb M. , Prager L. , Naumov S. , Krishtab M. , Armini S. , Van Der Voort P. , Baklanov M. R.
Published: January 2016

The ultra-violet (UV) and vacuum ultra-violet (VUV) resistance of bridging alkylene groups in organosilica films has been investigated. Similar to the Si-CH3 (methyl) bonds, the Si-CH2-Si (methylene) bonds are not affected by 5.6 eV irradiation. On the other hand, the concentration of the Si-CH2-CH2-Si (ethylene) groups decreases during such UV exposure. More significant difference in alkylene reduction is observed when the films are exposed to VUV (7.2 eV). The ethylene groups are depleted by more than 75% while only about 40% methylene and methyl groups loss is observed. The different sensitivity of bridging groups to VUV light should be taken into account during the development of curing and plasma etch processes of low-k materials based on periodic mesoporous organosilicas and oxycarbosilanes. The experimental results are qualitatively supported by ab-initio quantum-chemical calculations.
Anomalous lattice deformation in GaN/SiC(0001) measured by high-speed in situ synchrotron X-ray diffraction
Authors: Sasaki Takuo , Ishikawa Fumitaro , Takahasi Masamitu
Published: January 2016

We report an anomalous lattice deformation of GaN layers grown on SiC(0001) by molecular beam epitaxy. The evolution of the lattice parameters during the growth of the GaN layers was measured by in situ synchrotron X-ray diffraction. The lattice parameters in the directions parallel and normal to the surface showed significant deviation from the elastic strains expected for lattice-mismatched films on substrates up to a thickness of 10 nm. The observed lattice deformation was well explained by the incorporation of hydrostatic strains due to point defects. The results indicate that the control of point defects in the initial stage of growth is important for fabricating GaN-based optoelectronic devices.
Millisecond direct measurement of the magnetocaloric effect of a Fe2P-based compound by the mirage effect
Authors: Cugini F. , Porcari G. , Viappiani C. , Caron L. , dos Santos A. O. , Cardoso L. P. , Passamani E. C. , Proveti J. R. C. , Gama S. , Brück E. , Solzi M.
Published: January 2016

We present direct measurements of the magnetocaloric effect on a Fe2P-based compound induced by a milliseconds pulsed magnetic field of 1 T to test their possible use in high frequency (up to 100 Hz) thermomagnetic cycles. The reported measurements were performed with an innovative and versatile non-contact set up based on the mirage effect. The adiabatic temperature change of a MnFeP0.45As0.55 sample is presented and compared with measurements performed varying the same magnetic field in a time interval of 1 s and 100 ms. These results demonstrate the absence of kinetic constraints in the first-order phase transition of this sample induced on the milliseconds time scale. The study of the materials' response to millisecond magnetic field pulses represents a fundamental test for the development of more powerful and efficient magnetic refrigerators.
Transient phases during fast crystallization of organic thin films from solution
Authors: Wan Jing , Li Yang , Ulbrandt Jeffrey G. , Smilgies Detlef-M. , Hollin Jonathan , Whalley Adam C. , Headrick Randall L.
Published: January 2016

We report an in situ microbeam grazing incidence X-ray scattering study of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) organic semiconductor thin film deposition by hollow pen writing. Multiple transient phases are observed during the crystallization for substrate temperatures up to ≈93 °C. The layered smectic liquid-crystalline phase of C8-BTBT initially forms and preceedes inter-layer ordering, followed by a transient crystalline phase for temperature >60 °C, and ultimately the stable phase. Based on these results, we demonstrate a method to produce extremely large grain size and high carrier mobility during high-speed processing. For high writing speed (25 mm/s), mobility up to 3.0 cm2/V-s has been observed.
Bimesogen-enhanced flexoelectro-optic behavior of polymer stabilized cholesteric liquid crystal
Authors: Varanytsia A. , Chien L.-C.
Published: January 2016

We explore flexoelectro-optic effect in polymer stabilized cholesteric liquid crystals (CLC) with uniform lying helix texture. A method to enlarge the flexoelectric response of the CLC mixture is demonstrated by mixing two nematic liquid crystal host materials with large and small effective flexoelastic coefficients. By a choice of material composition of CLC mixture, a large angle of flexoelectrically driven in-plane rotation of helical axis with a submillisecond response time is obtained. Our findings will be useful for material design of future CLC mixtures for applications in flexoelectro-optic displays.
Vibration band gaps in double-vibrator pillared phononic crystal plate
Authors: Zhao Hao-Jiang , Guo Hong-Wei , Gao Ming-Xing , Liu Rong-Qiang , Deng Zong-Quan
Published: January 2016

This paper proposes a double-vibrator three-component pillared phononic crystal plate and theoretically studies the properties of vibration band gaps of this plate. The band structures and the displacement fields of the eigenmodes are calculated by the finite element method. Comparing the transmission power spectrums of the vibrations in the plate, the flexural vibration gap is proved more useful than the longitudinal vibration gap. The influence of the lattice constant, the height, and diameter of the pillars on the flexural vibration gaps are investigated. A supercell composed of the uni-vibrator and the double-vibrator unit cells is also investigated, and the analysis shows that the starting frequencies of the gaps in this supercell structure depend on the features of its pillars. This research can be used in the low frequency vibration insulation of plate structures.
Qualitative analysis of certain generalized classes of quadratic oscillator systems
Authors: Bagchi Bijan , Ghosh Samiran , Pal Barnali , Poria Swarup
Published: January 2016

We carry out a systematic qualitative analysis of the two quadratic schemes of generalized oscillators recently proposed by Quesne [J. Math. Phys. 56, 012903 (2015)]. By performing a local analysis of the governing potentials, we demonstrate that while the first potential admits a pair of equilibrium points one of which is typically a center for both signs of the coupling strength λ, the other points to a centre for λ < 0 but a saddle λ > 0. On the other hand, the second potential reveals only a center for both the signs of λ from a linear stability analysis. We carry out our study by extending Quesne’s scheme to include the effects of a linear dissipative term. An important outcome is that we run into a remarkable transition to chaos in the presence of a periodic force term fcosωt.
Layer characterization and photovoltaic properties of CdS/multi-wall carbon nanotube/n-Si device with an n-p-n transistor structure
Authors: Mohammed Muatez , Li Zhongrui , Chen Tar-pin
Published: January 2016

A new type of n-p-n transistor photovoltaic device based on CdS/multi-wall carbon nanotube (MWNT)/n-Si configuration was fabricated in a facile process. CdS quantum dots were deposited on fluorine-doped tin-oxide glass using a chemical bath deposition method, and MWNT film was coated on n-type Si substrate by airbrushing. The materials used for the n-p-n transistor solar cells were characterized by multiple techniques including X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman, Ultraviolet visible (UV-vis) spectrophotometer, and I-V characteristic measurements. The CdS layer acts as a good n-type material for the transistor solar cells. The thickness of the CdS layer can be controlled by the chemical bath deposition time to achieve different photovoltaic responses. I-V characteristic measurements show that the efficiency increases with increasing the thickness of the CdS thin layer. Compared with the tandem solar cells based on (p/n)–(p/n) semiconductor junctions, our n-p-n transistor solar cell has a simple structure without using tunnel junctions or wafer bonding schemes for interconnecting the cells.
Coaxial GaAs-AlGaAs core-multishell nanowire lasers with epitaxial gain control
Authors: Stettner T. , Zimmermann P. , Loitsch B. , Döblinger M. , Regler A. , Mayer B. , Winnerl J. , Matich S. , Riedl H. , Kaniber M. , Abstreiter G. , Koblmüller G. , Finley J. J.
Published: January 2016

We demonstrate the growth and single-mode lasing operation of GaAs-AlGaAs core-multishell nanowires (NW) with radial single and multiple GaAs quantum wells (QWs) as active gain media. When subject to optical pumping lasing emission with distinct s-shaped input-output characteristics, linewidth narrowing and emission energies associated with the confined QWs are observed. Comparing the low temperature performance of QW NW laser structures having 7 coaxial QWs with a nominally identical structure having only a single QW shows that the threshold power density reduces several-fold, down to values as low as ∼2.4 kW/cm2 for the multiple QW NW laser. This confirms that the individual radial QWs are electronically weakly coupled and that epitaxial design can be used to optimize the gain characteristics of the devices. Temperature-dependent investigations show that lasing prevails up to 300 K, opening promising new avenues for efficient III–V semiconductor NW lasers with embedded low-dimensional gain media.
Inhibiting electro-thermal breakdown of acrylic dielectric elastomer actuators by dielectric gel coating
Authors: La Thanh-Giang , Lau Gih-Keong
Published: January 2016

Electrical breakdown of dielectric elastomer actuators (DEA) is very localized; a spark and a pinhole (puncture) in dielectric ends up with short-circuit. This letter shows that prevention of electrothermal breakdown helps defer failure of DEAs even with conductive-grease electrodes. Dielectric gel encapsulation or coating (Dow Corning 3-4170) helps protect acrylic elastomer (VHB 4905), making it thermally more stable and delaying its thermal oxidation (burn) from 218 °C to 300 °C. Dielectric-gel-coated acrylic DEAs can withstand higher local leak-induced heating and thus achieve higher dielectric strengths than non-coated DEAs do.
InAs based terahertz quantum cascade lasers
Authors: Brandstetter Martin , Kainz Martin A. , Zederbauer Tobias , Krall Michael , Schönhuber Sebastian , Detz Hermann , Schrenk Werner , Andrews Aaron Maxwell , Strasser Gottfried , Unterrainer Karl
Published: January 2016

We demonstrate terahertz lasing emission from a quantum cascade structure, realized with InAs/AlAs0.16Sb0.84 heterostructures. Due to the lower effective electron mass, InAs based active regions are expected to provide a higher optical gain compared to structures consisting of GaAs or InGaAs. The growth by molecular beam epitaxy enabled the fabrication of monolayer-thick barriers, required for the active region, which is based on a 3-well resonant phonon depletion design. Devices were processed in a double-metal waveguide geometry to ensure high mode confinement and low optical losses. Lasing emission at 3.8 THz was observed at liquid helium temperatures by applying a magnetic field perpendicular to the layered structure in order to suppress parasitic scattering channels. These results demonstrate the feasibility of InAs based active regions for terahertz quantum cascade lasers, potentially enabling higher operating temperatures.
Fabrication of ring assemblies of nematic colloids and their electric response
Authors: Tamura Yuta , Kimura Yasuyuki
Published: January 2016

Colloidal particles with a limited number of interactive sites are called colloidal molecules, and their assemblies have been intensively studied to reveal complex micro-structures. In this study, we examine colloidal particles in nematic liquid crystals, so-called nematic colloids, as colloidal molecules and fabricated some non-close-packed assemblies. Micrometer-sized particles with homeotropic surface anchoring of liquid crystal in a homeotropic cell interact with each other through dipolar-type anisotropic interactions arising from the elastic deformation of the nematic field around the particles. Using optical tweezers, we have built two-dimensional colloidal assemblies with low packing densities, including polygon-rings, chains of polygon-rings, and lattices composed of octagon-rings in a hierarchical way from smaller structure units. Because the nematic field is sensitive to the electric field, the response of the polygon-rings to an alternative electric field has been studied. They exhibited homogeneous reversible shrink as large as 15%–22% to their original sizes under several volts.
Softness and non-spherical shape define the phase behavior and the structural properties of lysozyme in aqueous solutions
Authors: Baumketner A. , Melnyk R. , Holovko M. F. , Cai W. , Costa D. , Caccamo C.
Published: January 2016

In this study, Boltzmann inversion is applied in conjunction with molecular dynamics simulations to derive inter-molecular potential for protein lysozyme in aqueous solution directly from experimental static structure factor. The potential has a soft repulsion at short distances and an attraction well at intermediate distances that give rise to the liquid-liquid phase separation. Moreover, Gibbs ensemble Monte Carlo simulations demonstrate that a non-spherical description of lysozyme is better suited to correctly reproduce the experimentally observed properties of such a phase separation. Our findings shed new light on the common problem in molecular and cell biology: “How to model proteins in their natural aqueous environments?”
The coral communities of Yongle atoll: status, threats and conservation significance for coral reefs in South China Sea
Authors: Zhao Meixia , Yu Kefu , Shi Qi , Yang Hongqiang , Riegl Bernhard , Zhang Qiaomin , Yan Hongqiang , Chen Tianran , Liu Guohui , Lin Ziyun
Published: January 2016

Xisha Islands are in the central South China Sea and form one of the four large island groups in this region. They include more than 40 islands, reefs and cays, and have considerable ecological and biodiversity value, both intrinsically and as a source of larvae for coastal ecosystems throughout the South China Sea. Yongle atoll is the biggest and one of the most important atolls in the Xisha Islands. The detailed surveys of the marine habitats in the Yongle atoll were conducted from June to July 2013. This baseline survey revealed coral communities in a relatively healthy condition. Mean coral cover of different geomorphic habitats varied from 2 to 29%. Branching corals were most important, followed by encrusting and massive growth forms (48, 29 and 17% of coral cover). Pocillopora (29% of total cover in line transects), Porites (19%), Acropora (17%) and Montipora (16%) were the four dominant genera. Communities differentiated into four clusters, namely, lower reef slope, upper reef slope, outer reef flat, and inner reef flat and lagoon slope. This baseline investigation highlighted the ecological value of these reefs. Destructive fishing and overfishing are presently the most serious threats for these coral reefs. They should receive much more scientific and conservation attention.
LIM kinase activity is required for microtubule organising centre positioning in mouse oocyte meiosis
Authors: Li Xin , Zhu Yubo , Cao Yan , Wang Qian , Du Juan , Tian Jianhui , Liang Yuanjing , Ma Wei
Published: January 2016

LIM kinase 1 (LIMK1) activity is essential for cell migration and cell cycle progression. Little is known about LIMK1 expression and function in mammalian oocytes. In the present study we assessed LIMK1 protein expression, subcellular distribution and function during mouse oocyte meiosis. Western blot analysis revealed high and stable expression of LIMK1 from the germinal vesicle (GV) to MII stage. In contrast, activated LIMK1 (i.e. LIMK1 phosphorylated at threonine 508 (pLIMK1Thr508)) was only detected after GV breakdown, with levels increasing gradually to peak at MI and MII. Immunofluorescence showed pLIMK1Thr508 was colocalised with the microtubule organising centre (MTOC) components pericentrin and γ-tubulin at the spindle poles. A direct interaction between γ-tubulin and pLIMK1Thr508 was confirmed by co-immunoprecipitation. LIMK inhibition with 1 μM BMS3 damaged MTOC protein localisation to spindle poles, undermined the formation and positioning of functional MTOC and thus disrupted spindle formation and chromosome alignment. These effects were phenocopied by microinjection of LIMK1 antibody into mouse oocytes. In summary, the data demonstrate that LIMK activity is essential for MTOC organisation and distribution and so bipolar spindle formation and maintenance in mouse oocytes.
Limited tolerance by insects to high temperatures across tropical elevational gradients and the implications of global warming for extinction
Authors: García-Robledo Carlos , Kuprewicz Erin K. , Staines Charles L. , Erwin Terry L. , Kress W. John
Published: January 2016

Significance

Tolerance to high temperatures will determine the survival of animal species under projected global warming. Surprisingly little research has been conducted to elucidate how this trait changes in organisms living at different elevations of similar latitudes, especially in the tropics. DNA barcodes demonstrate that insect species previously thought to have broad elevational distributions and phenotypically plastic thermal tolerances actually comprise cryptic species complexes. These cryptic species occupy discrete elevational ranges, and their thermal tolerances seem to be locally adapted to temperatures in their life zones. The combination of high species endemism and local adaptation to temperature regimes may increase the extinction risk of high-elevation insects in a warming world.
Using decision pathway surveys to inform climate engineering policy choices
Authors: Gregory Robin , Satterfield Terre , Hasell Ariel
Published: January 2016

Significance

A growing number of scientists now believe that climate engineering technologies could be required to control global temperatures and protect ecosystems. Decision makers often rely on surveys to inform them about citizens’ views, but when novel technologies are involved results can fail to reflect the assumptions, knowledge, and values that underlie people’s choices. To bridge this gap, we describe a new, behaviorally and cognitively responsive “decision pathway” survey (n= 800) that mimics the conversational depth of small-group deliberations by adopting a broader context that includes competing objectives, civic priorities, factual information, and risk–benefit tradeoffs. Results yield important insights into citizens’ reasoning strategies and the ethical and governance concerns influencing the conditional nature of climate engineering policy choices.
Social relationships and physiological determinants of longevity across the human life span
Authors: Yang Yang Claire , Boen Courtney , Gerken Karen , Li Ting , Schorpp Kristen , Harris Kathleen Mullan
Published: January 2016

Significance

Although much evidence has accrued in research over the past 20 years on the strong causal associations between social relationships and health and longevity, important gaps remain in our understanding of the mechanisms, timing, and duration of these associations. This study integrates social and biological disciplinary perspectives and research to examine how social relationships “get under the skin” to affect physiological well-being as individuals age. By combining data from and harmonizing measurement across four large nationally representative, population-based, contemporary surveys using an innovative longitudinal life course design, this study provides previously unidentified evidence on the biological and life course mechanisms linking social relationship patterns with health. As such, our findings advance explanations of the emergence and progression of diseases across the human life span.
Changing climates of conflict: A social network experiment in 56 schools
Authors: Paluck Elizabeth Levy , Shepherd Hana , Aronow Peter M.
Published: January 2016

Significance

Despite a surge in policy and research attention to conflict and bullying among adolescents, there is little evidence to suggest that current interventions reduce school conflict. Using a large-scale field experiment, we show that it is possible to reduce conflict with a student-driven intervention. By encouraging a small set of students to take a public stance against typical forms of conflict at their school, our intervention reduced overall levels of conflict by an estimated 30%. Network analyses reveal that certain kinds of students (called “social referents”) have an outsized influence over social norms and behavior at the school. The study demonstrates the power of peer influence for changing climates of conflict, and suggests which students to involve in those efforts.
Revealing the burden of obesity using weight histories
Authors: Stokes Andrew , Preston Samuel H.
Published: January 2016

Significance

There is substantial uncertainty about the association between obesity and mortality. A major issue is the treatment of reverse causation, a phrase referring to the loss of weight among people who become ill. Weight histories are vital to addressing reverse causality, but few studies incorporate them. Here we introduce nationally representative data on lifetime maximum weight to distinguish individuals who were never obese from those who were formerly obese and lost weight. We formally investigate the performance of various models, finding that models that incorporate history perform better than the conventional approach based on a single observation of weight at the time of survey. We conclude that the burden of obesity is likely to be greater than is commonly appreciated.
Long-term clinical study and multiscale analysis of in vivo biodegradation mechanism of Mg alloy
Authors: Lee Jee-Wook , Han Hyung-Seop , Han Kyeong-Jin , Park Jimin , Jeon Hojeong , Ok Myoung-Ryul , Seok Hyun-Kwang , Ahn Jae-Pyoung , Lee Kyung Eun , Lee Dong-Ho , Yang Seok-Jo , Cho Sung-Youn , Cha Pil-Ryung , Kwon Hoon , Nam Tae-Hyun , Han Jee Hye Lo , Rho Hyoung-Jin , Lee Kang-Sik , Kim Yu-Chan , Mantovani Diego
Published: January 2016

Significance

In the past decade, countless studies have been performed to control the mechanical and corrosion property of magnesium-based alloy, which degrades in the physiological environment, to overcome the flaws of the inert implant materials and shift the paradigm of conventional bone fixation devices. Controlled degradation of Mg-5wt%Ca-1wt%Zn alloy results in the formation of biomimicking calcification matrix at the degrading interface to initiate the bone formation process. This process facilitates early bone healing and allows the complete replacement of biodegradable Mg implant by the new bone within 1 y of implantation, as demonstrated in 53 cases of successful long-term clinical study.
Heparanase-neutralizing antibodies attenuate lymphoma tumor growth and metastasis
Authors: Weissmann Marina , Arvatz Gil , Horowitz Netanel , Feld Sari , Naroditsky Inna , Zhang Yi , Ng Mary , Hammond Edward , Nevo Eviatar , Vlodavsky Israel , Ilan Neta
Published: January 2016

Significance

Heparanase is the predominant enzyme that cleaves heparan sulfate (HS) in mammals, a linear polysaccharide that is normally attached to a core protein, forming HS proteoglycans (HSPGs) that are abundant in the cell surface and extracellular matrix (ECM). Cleavage of HS by heparanase results in structural alterations of the ECM and release of ECM-bound factors that together stimulate cancer metastasis and angiogenesis. Here we provide evidence that heparanase is expressed by B-lymphomas, and heparanase inhibitors restrain tumor growth. Furthermore, we describe, for the first time to our knowledge, the development and characterization of heparanase-neutralizing monoclonal antibodies (mAbs) that inhibit cell invasion and tumor metastasis. Moreover, we show that these mAbs attenuate lymphoma growth by targeting heparanase in the tumor microenvironment.
MicroRNA-276 promotes egg-hatching synchrony by up-regulating
brm
in locusts
Authors: He Jing , Chen Qianquan , Wei Yuanyuan , Jiang Feng , Yang Meiling , Hao Shuguang , Guo Xiaojiao , Chen Dahua , Kang Le
Published: January 2016

Significance

Developmental synchrony, resulting from reduced fluctuation in individual development rate, is critical for swarming, migration, and social relationships of colonial animals. However, the molecular regulators of synchronous development are poorly understood. The migratory locust transits between high-density gregarious and low-density solitarious phases, with the former displaying more synchronous sexual maturation. Here, we identify a microRNA (miRNA), miR-276, expressed in the ovaries of female locusts mediating progeny egg-hatching synchrony by up-regulating its target
brahma
(
brm
), a transcription coactivator gene. Moreover, this up-regulation was dependent on the secondary structure of
brm
RNA. Our study demonstrates a noncanonical mechanism of miRNA-mediated gene regulation and provides important traits of locust phase transition for clues of possible prediction of pest plague outbreaks.
Exploring why Costa Rica outperforms the United States in life expectancy: A tale of two inequality gradients
Authors: Rosero-Bixby Luis , Dow William H.
Published: January 2016

Significance

Recent National Academies of Sciences reports have summarized evidence to understand why US health indicators lag those of other countries, in an effort to explore the fundamental question of why some populations live longer than others. However, this literature has failed to engage in the potentially more striking comparisons with countries that outperform the United States despite wielding many fewer resources. Costa Rica is one of a handful of middle-income countries with data to conduct this comparison. The finding that socioeconomic inequality in mortality is wider in the United States than in Costa Rica, and that people lower on the hierarchy in Costa Rica live longer than people in the equivalent position in the United States, is startling.
Neutralizing antibody titers against dengue virus correlate with protection from symptomatic infection in a longitudinal cohort
Authors: Katzelnick Leah C. , Montoya Magelda , Gresh Lionel , Balmaseda Angel , Harris Eva
Published: January 2016

Significance

The four dengue virus serotypes (DENV1–4) are the most prevalent arboviruses worldwide and cause outcomes ranging from inapparent infection to severe disease. Neutralizing antibodies are believed to be critical for protection and therefore for dengue vaccines, but the titers required to prevent symptomatic DENV infection have not been well established. Here, we show that higher preinfection neutralizing antibody titers correlate with lower probability of symptomatic infection in children in a longitudinal cohort study in Nicaragua. Further, we find evidence that levels of cross-reactive neutralizing antibodies are maintained over time, possibly due to reexposure. These findings provide insight into the determinants of DENV infection outcome and long-term immunity in an endemic setting and are relevant for dengue vaccine development.
On the dynamical nature of the active center in a single-site photocatalyst visualized by 4D ultrafast electron microscopy
Authors: Yoo Byung-Kuk , Su Zixue , Thomas John Meurig , Zewail Ahmed H.
Published: January 2016

Significance

The nature of the active site in (photo) catalysis is fundamental to our understanding of the processes involved, and to their control. Four-dimensional ultrafast electron microscopy (UEM) provides a dynamic probe for catalytic active site in photocatalytic materials thanks to its unprecedented resolution both in time (femtosecond) and space (angstrom). In this contribution, we visualize the femtosecond atomic movement at the titanium active center in a single-site photocatalyst. UEM allows us to investigate the structural dynamics of the radiation sensitive specimen by measuring time-resolved diffraction intensities from different lattice planes. These findings contribute fundamental insights for developing advanced photocatalysts and suggest broad ranges of applications.
Characteristics of Methadone Maintenance Treatment Patients Prescribed Opioid Analgesics
Authors: Glenn Matthew C. , Sohler Nancy L. , Starrels Joanna L. , Maradiaga Jeronimo , Jost John J. , Arnsten Julia H. , Cunningham Chinazo O.
Published: January 2016

Background: Opioid analgesic use and disorders have dramatically increased among the general American population and those receiving methadone maintenance treatment (MMT). Most research among MMT patients focuses on opioid analgesics misuse or disorders; few studies focus on MMT patients prescribed opioid analgesics. We describe demographic, clinical, and substance use characteristics of MMT patients prescribed opioid analgesics and compare them with MMT patients not prescribed opioid analgesics. Methods: We conducted a cross-sectional secondary data analysis using screening interviews from a parent study. From 2012 to 2015, we recruited adults from 3 MMT Bronx clinics. Questionnaire data included patterns of opioid analgesic use, substance use, comorbid illnesses, and demographic characteristics. Our main dependent variable was patients’ report of currently taking prescribed opioid analgesics. To compare characteristics between MMT patients prescribed and not prescribed opioid analgesics, we conducted chi-square tests, t tests, and Mann-Whitney U tests. Results: Of 611 MMT patients, most reported chronic pain (62.0%), hepatitis C virus (HCV) infection (52.1%), and current use of illicit substances (64.2%). Of the 29.8% who reported currently taking prescribed opioid analgesics, most misused their opioid analgesics (57.5%). Patients prescribed (versus not prescribed) opioid analgesics were more likely to report human immunodeficiency virus (HIV) infection (adjusted odds ratio [aOR] = 1.6, 95% confidence interval [CI]: 1.1–2.3) and chronic pain (aOR = 7.6, 95% CI: 4.6–12.6). Conclusion: Among MMT patients primarily in 3 Bronx clinics, nearly one third reported taking prescribed opioid analgesics. Compared with patients not prescribed opioid analgesics, those prescribed opioid analgesics were more likely to report chronic pain and HIV infection. However, between these patients, there was no difference in illicit substance use. These findings highlight the complexity of addressing chronic pain in MMT patients.
Effects of Omeprazole and Aluminum Hydroxide/Magnesium Hydroxide on Riociguat Absorption
Authors: Becker Corina , Frey Reiner , Unger Sigrun , Artmeier‐Brandt Ulrike , Weimann Gerrit , Mück Wolfgang
Published: January 2016

Riociguat, a soluble guanylate cyclase stimulator, is a novel therapy for the treatment of pulmonary hypertension. Riociguat bioavailability is reduced in neutral versus acidic conditions and therefore may be affected by concomitant use of medications that increase gastric pH. The effect of coadministration of the proton pump inhibitor omeprazole or the antacid AlOH/MgOH on the pharmacokinetics, safety, and tolerability of riociguat 2.5 mg was characterized in two open‐label, randomized, crossover studies in healthy males. In study 1, subjects pretreated for 4 days with omeprazole 40 mg received cotreatment with omeprazole plus riociguat or riociguat alone (no pretreatment) on day 5 (n = 12). In study 2, subjects received cotreatment with 10 mL AlOH/MgOH plus riociguat or riociguat alone (n = 12). Pre‐ and cotreatment with omeprazole decreased riociguat bioavailability (mean decreases in area under the plasma concentration‐time curve [AUC] and maximum concentration in plasma [Cmax] were 26% and 35%, respectively). Cotreatment with AlOH/MgOH resulted in greater decreases in riociguat bioavailability (mean decreases in AUC and Cmax were 34% and 56%, respectively). In both studies, most adverse events (AEs) were of mild intensity, and no serious AEs were reported. No additional safety signals were identified. Treatment with riociguat, with or without omeprazole or AlOH/MgOH, was well tolerated, with a good safety profile. Owing to the resulting increase of gastric pH, riociguat bioavailability is reduced by coadministration with AlOH/MgOH and, to a lesser extent, by coadministration with omeprazole. Thus, antacids should not be administered within an hour of receiving riociguat, but no dose adjustment is required for coadministration of proton pump inhibitors.
Acute Kidney Injury After Subarachnoid Hemorrhage
Authors: Tujjar Omar , Belloni Ilaria , Hougardy Jean-Michel , Scolletta Sabino , Vincent Jean-Louis , Creteur Jacques , Taccone Fabio S.
Published: January 2016

Background:

Acute kidney injury (AKI) is common in critically ill patients and may contribute to poor outcome. Few data are available on the incidence and impact of AKI in patients suffering from nontraumatic subarachnoid hemorrhage (SAH).

Methods:

We reviewed all patients admitted to our Department of Intensive Care with SAH over a 3-year period. Exclusion criteria were time from SAH symptoms to intensive care unit (ICU) admission >96 hours and ICU stay <48 hours. AKI was defined as sustained oligoanuria (urine output <0.5 mL/kg/h for 24 h) or an increase in plasma creatinine (≥0.3 mg/dL or a 1.5-fold increase from baseline level within 48 h). Neurological status was assessed at day 28 using the Glasgow Outcome Scale (GOS) (from 1=death to 5=good recovery; favorable outcome=GOS 4 to 5).

Results:

Of 243 patients admitted for SAH during the study period, 202 met the inclusion/exclusion criteria (median age 56 y, 78 male). Twenty-five patients (12%) developed AKI, a median of 8 (4 to 10) days after admission. Independent predictors of AKI were development of clinical vasospasm, and treatment with vancomycin. AKI was more frequent in ICU nonsurvivors than in survivors (11/50 vs. 14/152, P=0.03), and in patients with an unfavorable neurological outcome than in other patients (17/93 vs. 8/109, P=0.03). Nevertheless, in multivariable regression analysis, AKI was not an independent predictor of outcome.

Conclusions:

AKI occurred in >10% of patients after SAH. These patients had more severe neurological impairment and needed more aggressive ICU therapy; AKI did not significantly influence outcome.
Models of social evolution: can we do better to predict ‘who helps whom to achieve what’?
Authors: Rodrigues António M. M. , Kokko Hanna
Published: January 2016

Models of social evolution and the evolution of helping have been classified in numerous ways. Two categorical differences have, however, escaped attention in the field. Models tend not to justify why they use a particular assumption structure about who helps whom: a large number of authors model peer-to-peer cooperation of essentially identical individuals, probably for reasons of mathematical convenience; others are inspired by particular cooperatively breeding species, and tend to assume unidirectional help where subordinates help a dominant breed more efficiently. Choices regarding what the help achieves (i.e. which life-history trait of the helped individual is improved) are similarly made without much comment: fecundity benefits are much more commonly modelled than survival enhancements, despite evidence that these may interact when the helped individual can perform life-history reallocations (load-lightening and related phenomena). We review our current theoretical understanding of effects revealed when explicitly asking ‘who helps whom to achieve what’, from models of mutual aid in partnerships to the very few models that explicitly contrast the strength of selection to help enhance another individual's fecundity or survival. As a result of idiosyncratic modelling choices in contemporary literature, including the varying degree to which demographic consequences are made explicit, there is surprisingly little agreement on what types of help are predicted to evolve most easily. We outline promising future directions to fill this gap.
Non-kin cooperation in bats
Authors: Wilkinson Gerald S. , Carter Gerald G. , Bohn Kirsten M. , Adams Danielle M.
Published: January 2016

Many bats are extremely social. In some cases, individuals remain together for years or even decades and engage in mutually beneficial behaviours among non-related individuals. Here, we summarize ways in which unrelated bats cooperate while roosting, foraging, feeding or caring for offspring. For each situation, we ask if cooperation involves an investment, and if so, what mechanisms might ensure a return. While some cooperative outcomes are likely a by-product of selfish behaviour as they are in many other vertebrates, we explain how cooperative investments can occur in several situations and are particularly evident in food sharing among common vampire bats (Desmodus rotundus) and alloparental care by greater spear-nosed bats (Phyllostomus hastatus). Fieldwork and experiments on vampire bats indicate that sharing blood with non-kin expands the number of possible donors beyond kin and promotes reciprocal help by strengthening long-term social bonds. Similarly, more than 25 years of recapture data and field observations of greater spear-nosed bats reveal multiple cooperative investments occurring within stable groups of non-kin. These studies illustrate how bats can serve as models for understanding how cooperation is regulated in social vertebrates.
The evolution of altruistic social preferences in human groups
Authors: Silk Joan B. , House Bailey R.
Published: January 2016

In this paper, we consider three hypotheses to account for the evolution of the extraordinary capacity for large-scale cooperation and altruistic social preferences within human societies. One hypothesis is that human cooperation is built on the same evolutionary foundations as cooperation in other animal societies, and that fundamental elements of the social preferences that shape our species' cooperative behaviour are also shared with other closely related primates. Another hypothesis is that selective pressures favouring cooperative breeding have shaped the capacity for cooperation and the development of social preferences, and produced a common set of behavioural dispositions and social preferences in cooperatively breeding primates and humans. The third hypothesis is that humans have evolved derived capacities for collaboration, group-level cooperation and altruistic social preferences that are linked to our capacity for culture. We draw on naturalistic data to assess differences in the form, scope and scale of cooperation between humans and other primates, experimental data to evaluate the nature of social preferences across primate species, and comparative analyses to evaluate the evolutionary origins of cooperative breeding and related forms of behaviour.
A simple rule for the evolution of contingent cooperation in large groups
Authors: Schonmann Roberto H. , Boyd Robert
Published: January 2016

Humans cooperate in large groups of unrelated individuals, and many authors have argued that such cooperation is sustained by contingent reward and punishment. However, such sanctioning systems can also stabilize a wide range of behaviours, including mutually deleterious behaviours. Moreover, it is very likely that large-scale cooperation is derived in the human lineage. Thus, understanding the evolution of mutually beneficial cooperative behaviour requires knowledge of when strategies that support such behaviour can increase when rare. Here, we derive a simple formula that gives the relatedness necessary for contingent cooperation in
n
-person iterated games to increase when rare. This rule applies to a wide range of pay-off functions and assumes that the strategies supporting cooperation are based on the presence of a threshold fraction of cooperators. This rule suggests that modest levels of relatedness are sufficient for invasion by strategies that make cooperation contingent on previous cooperation by a small fraction of group members. In contrast, only high levels of relatedness allow the invasion by strategies that require near universal cooperation. In order to derive this formula, we introduce a novel methodology for studying evolution in group structured populations including local and global group-size regulation and fluctuations in group size.
Reputation, a universal currency for human social interactions
Authors: Milinski Manfred
Published: January 2016

Decision rules of reciprocity include ‘I help those who helped me’ (direct reciprocity) and ‘I help those who have helped others’ (indirect reciprocity), i.e. I help those who have a reputation to care for others. A person's reputation is a score that members of a social group update whenever they see the person interacting or hear at best multiple gossip about the person's social interactions. Reputation is the current standing the person has gained from previous investments or refusal of investments in helping others. Is he a good guy, can I trust him or should I better avoid him as a social partner? A good reputation pays off by attracting help from others, even from strangers or members from another group, if the recipient's reputation is known. Any costly investment in others, i.e. direct help, donations to charity, investment in averting climate change, etc. increases a person's reputation. I shall argue and illustrate with examples that a person's known reputation functions like money that can be used whenever the person needs help. Whenever possible I will present tests of predictions of evolutionary theory, i.e. fitness maximizing strategies, mostly by economic experiments with humans.
Biological trade and markets
Authors: Hammerstein Peter , Noë Ronald
Published: January 2016

Cooperation between organisms can often be understood, like trade between merchants, as a mutually beneficial exchange of services, resources or other ‘commodities’. Mutual benefits alone, however, are not sufficient to explain the evolution of trade-based cooperation. First, organisms may reject a particular trade if another partner offers a better deal. Second, while human trade often entails binding contracts, non-human trade requires unwritten ‘terms of contract’ that ‘self-stabilize’ trade and prevent cheating even if all traders strive to maximize fitness. Whenever trading partners can be chosen, market-like situations arise in nature that biologists studying cooperation need to account for. The mere possibility of exerting partner choice stabilizes many forms of otherwise cheatable trade, induces competition, facilitates the evolution of specialization and often leads to intricate forms of cooperation. We discuss selected examples to illustrate these general points and review basic conceptual approaches that are important in the theory of biological trade and markets. Comparing these approaches with theory in economics, it turns out that conventional models—often called ‘Walrasian’ markets—are of limited relevance to biology. In contrast, early approaches to trade and markets, as found in the works of Ricardo and Cournot, contain elements of thought that have inspired useful models in biology. For example, the concept of comparative advantage has biological applications in trade, signalling and ecological competition. We also see convergence between post-Walrasian economics and biological markets. For example, both economists and biologists are studying ‘principal–agent’ problems with principals offering jobs to agents without being sure that the agents will do a proper job. Finally, we show that mating markets have many peculiarities not shared with conventional economic markets. Ideas from economics are useful for biologists studying cooperation but need to be taken with caution.
Proteomic indicators of oxidation and hydration state in colorectal cancer
Authors: Dick Jeffrey M.
Published: January 2016

New integrative approaches are needed to harness the potential of rapidly growing datasets of protein expression and microbial community composition in colorectal cancer (CRC). Chemical and thermodynamic models offer theoretical tools to describe populations of biomacromolecules and their relative potential for formation in different microenvironmental conditions. The average oxidation state of carbon (ZC) can be calculated as an elemental ratio from the chemical formulas of proteins, and water demand per residue is computed by writing the overall formation reactions of proteins from basis species. Using reported results from clinical proteomic studies and microbial community profiling, many datasets exhibit higher mean ZC or of proteins in carcinoma or adenoma compared to normal tissue. Microbial protein compositions have lower ZC in bacteria enriched in fecal samples from cancer patients. In thermodynamic calculations, the potential for formation of the cancer-related proteins is energetically favored by changes in the chemical activity of H2O and fugacity of O2 that reflect the compositional differences. The compositional analysis suggests that a systematic shift in chemical composition is an essential feature of the cancer proteome, and the thermodynamic descriptions show that the observed proteomic transformations could be promoted by microenvironments shifted toward more oxidizing conditions and increased hydration levels.