bluuebunny/crossref_metadata_2025 huggingface dataset:
Tunable damping-like and field-like spin-orbit-torque in Pt/Co/HfO2 films via interfacial charge transfer
Authors: Peng W. L. , Zhang J. Y. , Feng G. N. , Xu X. L. , Yang C. , Jia Y. L. , Yu G. H.
Published: October 2019

The spin–orbit-torque (SOT) consists of dampinglike torque (DLT) and fieldlike torque (FLT), where the combined effects of these two torques need further consideration for efficient SOT switching. Here, the tunable correlation between the DLT and FLT is investigated in Pt/Co/HfO2 multilayers with different annealing temperatures (Ta). With increasing Ta, the FLT decreases monotonously, while both the sign and the magnitude of DLT are changed. Interfacial analysis results reveal that the tunable correlation of them is strongly dependent on the interfacial electron structure between the Co and HfO2 layer. The interfacial charge transfer between the Co, O, and Hf atoms could modify interfacial spin–orbit coupling and the crystal electric field (ECEF), which promotes the interface-generated SOT. This work demonstrates an effective method to tune the correlation of the two SOT components, a desirable feature which will be beneficial for the design of SOT-based devices.
Ligand memory effect in purple quantum dot LEDs
Authors: Blauth Christian , Mulvaney Paul , Hirai Tadahiko
Published: October 2019

We report a ligand-dependent, trap state memory effect in a purple quantum dot light emitting diode. The measured, bistable current-voltage characteristics show a high conductance state and a low conductance state. Thereby, a memory window with an ON state and an OFF state is achieved, which can be reversed by applying a negative bias. The height of the memory window depends strongly on the length of the ligand passivating the quantum dot (QD). Together with a 5 nm thick aluminum film under the hole transport layer, charges accumulate at the charge transport/quantum dot ligand interface, leading to an increase in conductance during the forward voltage sweep. During a reverse voltage sweep, previously injected charge carriers recombine until the active layer is free of charge carriers. Voltage-capacitance measurements confirm the changes in the charge carrier population within the active layer and demonstrate that they depend on both the direction of the bias sweep and ligands surrounding the QD.
Boosting the doping efficiency of Mg in p-GaN grown on the free-standing GaN substrates
Authors: Sang Liwen , Ren Bing , Endo Raimu , Masuda Takuya , Yasufuku Hideyuki , Liao Meiyong , Nabatame Toshihide , Sumiya Masatomo , Koide Yasuo
Published: October 2019

The Mg doping efficiency is found to be drastically enhanced in the p-GaN films grown on the free-standing GaN substrates by metal organic chemical vapor deposition. The free hole concentrations are five and ten times higher in the lightly and heavily Mg-doped homoepitaxial p-GaN, respectively, than those in the p-GaN-on-GaN/sapphires grown and activated at the same conditions although the Mg incorporation concentrations {[Mg]} are much lower. The indication of the p-type conductivity in the photoluminescence spectra at room temperature in p-GaN-on-GaN substrates is found to be the dominant ultraviolet luminescence band located at around 3.26 eV. This behavior is different in the heteroepitaxial p-GaN, for which the fingerprint of the p-type conductivity is the emergence of blue luminescence bands at around 2.9 eV. The markedly enhanced activation efficiency is attributed to the suppression of self-compensation centers in the high-quality homoepitaxial films. The Mg-Ga-O disordered layer, which is typically observed on the surface of p-GaN-on-GaN/sapphires due to the Mg diffusion along edge-type dislocations, is also inhibited on the homoepitaxial p-GaN film, which is beneficial for the stable operation of the vertical-type metal-oxide-semiconductor field effect transistors.
Vibrationally resolved photoelectron spectroscopy of oligothiophene radical anions
Authors: Thurston Glen K. , Sagan Cole R. , Garand Etienne
Published: October 2019

Vibrationally resolved photoelectron spectroscopy of terthiophene, quaterthiophene, and quinquethiophene radical anions is presented. The increased spectral resolution afforded by the combination of slow photoelectron velocity-map imaging and ion cooling in a cryogenic ion trap allows the characterization of vibronic structures within the S0 and T1 states. Analysis of the spectra, aided by electronic structure calculations and Franck-Condon simulations, revealed evidence for significant contributions from kinetically trapped higher energy conformers in the anion-to-triplet transitions. Unlike the lowest energy structures, where all the thiophene linkers are in the trans configuration, these higher energy conformers contain at least one cis linker. We also found that the adiabatic Franck-Condon simulations drastically underestimated the intensities of some vibronic features in the singlet ground state spectra due to large geometry changes upon photodetachment and anharmonic couplings in the singlet state.
Transport in armchair graphene nanoribbons and in ordinary waveguides
Authors: Zubair M. , Bahrami M. , Vasilopoulos P.
Published: October 2019

We study dc and ac transport along armchair graphene nanoribbons using the k⋅p spectrum and eigenfunctions and general linear-response expressions for the conductivities. Then, we contrast the results with those for transport along ordinary waveguides. In all cases, we assess the influence of elastic scattering by impurities, describe it quantitatively with a Drude-type contribution to the current previously not reported, and evaluate the corresponding relaxation time for long- and short-range impurity potentials. We show that this contribution dominates the response at very low frequencies. In both cases, the conductivities increase with the electron density and show cusps when new subbands start being occupied. As functions of the frequency, the conductivities in armchair graphene nanoribbons exhibit a much richer peak structure than in ordinary waveguides: in the former, intraband and interband transitions are allowed, whereas in the latter, only the intraband ones occur. This difference can be traced to that between the corresponding spectra and eigenfunctions.
InAs/InP quantum dot VECSEL emitting at 1.5 μm
Authors: Nechay K. , Mereuta A. , Paranthoen C. , Brévalle G. , Levallois C. , Alouini M. , Chevalier N. , Perrin M. , Suruceanu G. , Caliman A. , Guina M. , Kapon E.
Published: October 2019

A high-power InAs quantum dot (QD) vertical-external-cavity surface-emitting laser emitting at 1.5 μm is reported. The active region employs 20 layers of high-density Stranski–Krastanow InAs quantum dots on an InP substrate. The QD density and emission wavelength were independently adjusted by employing a double-cap growth sequence. Optimization of the spacer layer thickness and strain compensation rendered possible nucleation of a relatively high number of QD layers per antinode of the electromagnetic standing wave, which in turn enabled a high output power continuous wave operation of about 2.2 W. The operation wavelength could be tuned over 60 nm, taking advantage of the broadband gain characteristic of QD media.
Electrical properties and interface abruptness of AlSiO gate dielectric grown on 0001¯ N-polar and (0001) Ga-polar GaN
Authors: Sayed Islam , Bonef Bastien , Liu Wenjian , Chan Silvia , Georgieva Jana , Speck James S. , Keller Stacia , Mishra Umesh K.
Published: October 2019

The electrical properties and the interface abruptness of aluminum silicon oxide (AlSiO) dielectric grown in situ on 0001¯ N-polar and (0001) Ga-polar GaN by metal organic chemical vapor deposition were studied by means of capacitance-voltage (CV) and atom probe tomography (APT) measurements. The growth of AlSiO on N-polar GaN resulted in a positive flatband voltage shift of 2.27 V with respect to that on Ga-polar GaN, which exemplifies the influence of the GaN surface polarization charge on the electrical properties of GaN-based metal oxide semiconductor (MOS) devices. The AlSiO/GaN(N-polar) interface was sharp, which resulted in nondispersive CV characteristics and a relatively low density of interface states (Dit) of 1.48 × 1012 cm−2. An intermixed layer of AlGaSiO was present at the interface between AlSiO and Ga-polar GaN, which contributed to the measured dispersive CV characteristics and resulted in an ∼2× higher Dit than that on N-polar GaN. The superior properties of the N-polar AlSiO MOS devices are promising for further advancement of N-polar GaN-based high electron mobility transistors for high-frequency and power electronics applications.
Shock compression of fused silica: An impedance matching standard
Authors: Root Seth , Townsend Joshua P. , Knudson Marcus D.
Published: October 2019

The properties of silica (SiO2) at extreme conditions have important applications for planetary processes and for high pressure research. We report the results of 125 plate impact shock compression experiments on fused silica spanning 200–1100 GPa using the Z machine at Sandia National Laboratories. Additionally, we present a complementary set of density functional theory based molecular dynamics calculations based on an amorphous reference state that extend the Hugoniot to 2500 GPa. We find good agreement between the Z data, extant laser driven shock compression experiment data, and computational results over most of the pressure range. With these results, fused silica can be used as a new impedance matching standard for shock compression experiments.
The dual–function of lipoic acid groups as surface anchors and sulfhydryl reactive sites on polymer–stabilized QDs and Au nanocolloids
Authors: Jin Zhicheng , Kapur Anshika , Wang Wentao , Diaz Hernandez Juan , Thakur Mannat , Mattoussi Hedi
Published: October 2019

Coating inorganic nanocrystals [e.g., quantum dots (QDs) and gold nanoparticles] with polymer ligands presenting multiple lipoic acid anchoring groups provides nanocolloids with remarkable long-term colloidal and photophysical stability. Here, we show that the natural swelling of macromolecules leaves a fraction of the lipoic acid groups in the surface coating free, which are targeted for activation and conjugation to target molecules, using the reliable sulfhydryl-to-maleimide reaction. This implies that simple and efficient functionalization of the nanocrystals can be achieved without introducing additional reactive groups in the coating. We apply a photomediated ligand exchange strategy to luminescent QDs and AuNPs and react the resulting nanocrystals with maleimide Cy3 dye. We then use optical absorption and resonance energy transfer measurements applied to QD-Cy3 and AuNP-Cy3 conjugates to extract estimates for the fraction of accessible lipoic acid groups per QD or AuNP. In addition, we demonstrate the potential utility of this approach by constructing a ratiometric pH sensor made of QD-SNARF conjugates. Our ligand design combined with the photoligation strategy yield colloidally stable dispersions of QDs and AuNPs that present accessible reactive thiols, without introducing new functionalities or requiring disulfide reducing reagents, making them useful for potential use in applications such as biological sensing and imaging.
Improvement of anti-fatigued strain in KTN-based single crystals with regular periodic hierarchical domain structure
Authors: Tian Hao , Huang Fei , Meng Xiangda , Wang Yu , Xian Zhongzhao , Hu Chengpeng , Zhou Zhongxiang
Published: October 2019

Ion doping can significantly affect the microdomain structures and the properties of ferroelectric materials, such as strain and piezoelectric properties. Here, we report a remarkable improvement in the antihysteretic and antifatigue strain properties via Mn and Fe codoping in KTN single crystals. By comparison among pure KTN, Mn-doped KTN, and (Mn, Fe) codoped KTN, the results reveal that Mn and Fe doping can significantly enhance antifatigue properties and reduce the domain switching fields, exhibiting large strain (0.17%) under a low driven field (5 kV cm−1), giant d33* ∼ 3160 pC N−1, low strain hysteresis (Hys < 20%), and antifatigue (just about 6% drop after 105 cycles). In addition, the microdomain structures' images reveal that Mn and Fe codoping can not only affect the domain structure and size but also induce the formation of a regular periodic hierarchical domain structure. Therefore, Mn&Fe:KTN is expected to be one of the most potential ferroelectric materials, which is meaningful for the further study of antifatigue in KTN-based ferroelectric materials.
No observed reduction of non-attendance rate in telehealth models of care
Authors: Greenup E. P. , Best D. , Page M. , Potts B.
Published: October 2019

Objective
This study investigated the provision of public specialist out-patient services in Queensland delivered in traditional hospital settings (in person) or through a two-way synchronous videoconferencing session (telehealth). Rates of attendance between these delivery methods were compared to detect any difference in rates of non-attendance among patients.

Methods
An extract of all specialist out-patient appointments reported in Queensland Health’s corporate patient administration systems between 1 July 2017 and 30 June 2018 was obtained (n = 2921702). Variables including how the service was delivered and whether the patient attended were captured for each event.

Results
No reduction in non-attendance was observed in the telehealth patient group (9.1%) compared with in-person service delivery (9.1% vs 7.9% respectively; = 113.56, P < 0.001, relative risk = 1.15).

Discussion
The study found no evidence that telehealth is effective at reducing rates of non-attendance in a specialist out-patient setting. This supports existing findings that most non-attendance is the result of forgetfulness or confusion with appointment details, to which telehealth appointments are also vulnerable.

What is known about the topic?
Non-attendance of out-patient appointments remains a persistent and costly problem for public and private providers of health services. Forgetting or being confused about appointment details are the most commonly reported reasons for patient non-attendance.

What does this paper add?
Telehealth models of care are increasingly being offered by health service providers, reducing travel requirements to all patients, particularly those in regional and remote settings. However, telehealth models of care do not address the most common reasons for patient non-attendance and telehealth patients are not less likely to miss their appointments.

What are the implications for practitioners?
Suggestions that telehealth models of care can reduce rates of non-attendance should be treated with caution by health service administrators and clinicians. More timely appointment reminders and easier processes to cancel or reschedule appointments remain the most effective techniques for reducing non-attendance.
Combination anti–CTLA-4 plus anti–PD-1 checkpoint blockade utilizes cellular mechanisms partially distinct from monotherapies
Authors: Wei Spencer C. , Anang Nana-Ama A. S. , Sharma Roshan , Andrews Miles C. , Reuben Alexandre , Levine Jacob H. , Cogdill Alexandria P. , Mancuso James J. , Wargo Jennifer A. , Pe’er Dana , Allison James P.
Published: October 2019

Immune checkpoint blockade therapy targets T cell-negative costimulatory molecules such as cytotoxic T lymphocyte antigen-4 (CTLA-4) and programmed cell death-1 (PD-1). Combination anti–CTLA-4 and anti–PD-1 blockade therapy has enhanced efficacy, but it remains unclear through what mechanisms such effects are mediated. A critical question is whether combination therapy targets and modulates the same T cell populations as monotherapies. Using a mass cytometry-based systems approach, we comprehensively profiled the response of T cell populations to monotherapy and combination anti–CTLA-4 plus anti–PD-1 therapy in syngeneic murine tumors and clinical samples. Most effects of monotherapies were additive in the context of combination therapy; however, multiple combination therapy-specific effects were observed. Highly phenotypically exhausted cluster of differentiation 8 (CD8) T cells expand in frequency following anti–PD-1 monotherapy but not combination therapy, while activated terminally differentiated effector CD8 T cells expand only following combination therapy. Combination therapy also led to further increased frequency of T helper type 1 (Th1)-like CD4 effector T cells even though anti–PD-1 monotherapy is not sufficient to do so. Mass cytometry analyses of peripheral blood from melanoma patients treated with immune checkpoint blockade therapies similarly revealed mostly additive effects on the frequencies of T cell subsets along with unique modulation of terminally differentiated effector CD8 T cells by combination ipilimumab plus nivolumab therapy. Together, these findings indicate that dual blockade of CTLA-4 and PD-1 therapy is sufficient to induce unique cellular responses compared with either monotherapy.
Arm movements induced by noninvasive optogenetic stimulation of the motor cortex in the common marmoset
Authors: Ebina Teppei , Obara Keitaro , Watakabe Akiya , Masamizu Yoshito , Terada Shin-Ichiro , Matoba Ryota , Takaji Masafumi , Hatanaka Nobuhiko , Nambu Atsushi , Mizukami Hiroaki , Yamamori Tetsuo , Matsuzaki Masanori
Published: October 2019

Optogenetics is now a fundamental tool for investigating the relationship between neuronal activity and behavior. However, its application to the investigation of motor control systems in nonhuman primates is rather limited, because optogenetic stimulation of cortical neurons in nonhuman primates has failed to induce or modulate any hand/arm movements. Here, we used a tetracycline-inducible gene expression system carrying CaMKII promoter and the gene encoding a Channelrhodopsin-2 variant with fast kinetics in the common marmoset, a small New World monkey. In an awake state, forelimb movements could be induced when Channelrhodopsin-2−expressing neurons in the motor cortex were illuminated by blue laser light with a spot diameter of 1 mm or 2 mm through a cranial window without cortical invasion. Forelimb muscles responded 10 ms to 50 ms after photostimulation onset. Long-duration (500 ms) photostimulation induced discrete forelimb movements that could be markerlessly tracked with charge-coupled device cameras and a deep learning algorithm. Long-duration photostimulation mapping revealed that the primary motor cortex is divided into multiple domains that can induce hand and elbow movements in different directions. During performance of a forelimb movement task, movement trajectories were modulated by weak photostimulation, which did not induce visible forelimb movements at rest, around the onset of task-relevant movement. The modulation was biased toward the movement direction induced by the strong photostimulation. Combined with calcium imaging, all-optical interrogation of motor circuits should be possible in behaving marmosets.
Repertoire-wide phylogenetic models of B cell molecular evolution reveal evolutionary signatures of aging and vaccination
Authors: Hoehn Kenneth B. , Vander Heiden Jason A. , Zhou Julian Q. , Lunter Gerton , Pybus Oliver G. , Kleinstein Steven H.
Published: October 2019

In order to produce effective antibodies, B cells undergo rapid somatic hypermutation (SHM) and selection for binding affinity to antigen via a process called affinity maturation. The similarities between this process and evolution by natural selection have led many groups to use phylogenetic methods to characterize the development of immunological memory, vaccination, and other processes that depend on affinity maturation. However, these applications are limited by the fact that most phylogenetic models are designed to be applied to individual lineages comprising genetically diverse sequences, while B cell repertoires often consist of hundreds to thousands of separate low-diversity lineages. Further, several features of affinity maturation violate important assumptions in standard phylogenetic models. Here, we introduce a hierarchical phylogenetic framework that integrates information from all lineages in a repertoire to more precisely estimate model parameters while simultaneously incorporating the unique features of SHM. We demonstrate the power of this repertoire-wide approach by characterizing previously undescribed phenomena in affinity maturation. First, we find evidence consistent with age-related changes in SHM hot-spot targeting. Second, we identify a consistent relationship between increased tree length and signs of increased negative selection, apparent in the repertoires of recently vaccinated subjects and those without any known recent infections or vaccinations. This suggests that B cell lineages shift toward negative selection over time as a general feature of affinity maturation. Our study provides a framework for undertaking repertoire-wide phylogenetic testing of SHM hypotheses and provides a means of characterizing dynamics of mutation and selection during affinity maturation.
Phylogenomics reveals the evolutionary timing and pattern of butterflies and moths
Authors: Kawahara Akito Y. , Plotkin David , Espeland Marianne , Meusemann Karen , Toussaint Emmanuel F. A. , Donath Alexander , Gimnich France , Frandsen Paul B. , Zwick Andreas , dos Reis Mario , Barber Jesse R. , Peters Ralph S. , Liu Shanlin , Zhou Xin , Mayer Christoph , Podsiadlowski Lars , Storer Caroline , Yack Jayne E. , Misof Bernhard , Breinholt Jesse W.
Published: October 2019

Butterflies and moths (Lepidoptera) are one of the major superradiations of insects, comprising nearly 160,000 described extant species. As herbivores, pollinators, and prey, Lepidoptera play a fundamental role in almost every terrestrial ecosystem. Lepidoptera are also indicators of environmental change and serve as models for research on mimicry and genetics. They have been central to the development of coevolutionary hypotheses, such as butterflies with flowering plants and moths’ evolutionary arms race with echolocating bats. However, these hypotheses have not been rigorously tested, because a robust lepidopteran phylogeny and timing of evolutionary novelties are lacking. To address these issues, we inferred a comprehensive phylogeny of Lepidoptera, using the largest dataset assembled for the order (2,098 orthologous protein-coding genes from transcriptomes of 186 species, representing nearly all superfamilies), and dated it with carefully evaluated synapomorphy-based fossils. The oldest members of the Lepidoptera crown group appeared in the Late Carboniferous (∼300 Ma) and fed on nonvascular land plants. Lepidoptera evolved the tube-like proboscis in the Middle Triassic (∼241 Ma), which allowed them to acquire nectar from flowering plants. This morphological innovation, along with other traits, likely promoted the extraordinary diversification of superfamily-level lepidopteran crown groups. The ancestor of butterflies was likely nocturnal, and our results indicate that butterflies became day-flying in the Late Cretaceous (∼98 Ma). Moth hearing organs arose multiple times before the evolutionary arms race between moths and bats, perhaps initially detecting a wide range of sound frequencies before being co-opted to specifically detect bat sonar. Our study provides an essential framework for future comparative studies on butterfly and moth evolution.
Expert-level detection of acute intracranial hemorrhage on head computed tomography using deep learning
Authors: Kuo Weicheng , Hӓne Christian , Mukherjee Pratik , Malik Jitendra , Yuh Esther L.
Published: October 2019

Significance

Computed tomography (CT) of the head is the workhorse medical imaging modality used worldwide to diagnose neurologic emergencies. However, these gray scale images are limited by low signal-to-noise, poor contrast, and a high incidence of image artifacts. A unique challenge is to identify tiny subtle abnormalities in a large 3D volume with near-perfect sensitivity. We used a single-stage, end-to-end, fully convolutional neural network to achieve accuracy levels comparable to that of highly trained radiologists, including both identification and localization of abnormalities that are missed by radiologists.
Metallic iron limits silicate hydration in Earth’s transition zone
Authors: Zhu Feng , Li Jie , Liu Jiachao , Dong Junjie , Liu Zhenxian
Published: October 2019

Significance

Some studies suggested that the Earth’s mantle transition zone (MTZ) consists of hydrous silicates while others proposed that it contains iron metal. Here we show that the metallic iron dehydrates hydrous silicates at MTZ conditions, implying that global hydration of silicates and metal saturation are incompatible. Comparing iron production in and water injection to the MTZ, we found that the hydration of MTZ silicates is likely limited to <0.1 wt %, while large amount of the hydrogen can be stored as iron hydride and hydrogen fluid instead. Water-rich domains may still exist near the modern active subducted slabs. Our finding connects the water content to the oxidation state of the MTZ, thus providing a different perspective on volatile cycles in the mantle.
Nanomechanical properties of steric zipper globular structures
Authors: Lester-Zer Neta , Ghrayeb Mnar , Chai Liraz
Published: October 2019

Significance

The increase in life expectancy has nowadays positioned neurodegenerative diseases as a leading cause of death. Neurodegeneration is related to early amyloid protein aggregation; however, in the lack of an aggregation mechanism, neurodegenerative diseases still remain neither cured nor prevented. In a fundamental study of amyloid early aggregation, we have characterized the nanomechanical properties of steric zippers, the shortest amyloid sequences that yet bear high propensity to form fibers. We have found that steric zippers form unprecedented globular structures on route to fiber formation that exhibit a characteristic nanomechanical fingerprint. Approaching amyloid fiber formation from a basic physical perspective, this study sheds light on the internal structure of amyloid precursor chains, providing insight into the design of antiamyloid drugs.
Modulation of the pupillary response by the content of visual working memory
Authors: Zokaei Nahid , Board Alexander G. , Manohar Sanjay G. , Nobre Anna C.
Published: October 2019

Significance

We report, across 3 complementary studies, that attention in visual working memory leads to top-down modulations of the pupillary response, in the absence of any visual input or anticipation of any change in brightness. These findings strengthen the view of the sensory recruitment, all the way down to the earliest synapses in the visual system. The thought-provoking corollary to our findings is that the pupils provide a reliable measure of what is in the focus of the mind.
GenBank is a reliable resource for 21st century biodiversity research
Authors: Leray Matthieu , Knowlton Nancy , Ho Shian-Lei , Nguyen Bryan N. , Machida Ryuji J.
Published: October 2019

Traditional methods of characterizing biodiversity are increasingly being supplemented and replaced by approaches based on DNA sequencing alone. These approaches commonly involve extraction and high-throughput sequencing of bulk samples from biologically complex communities or samples of environmental DNA (eDNA). In such cases, vouchers for individual organisms are rarely obtained, often unidentifiable, or unavailable. Thus, identifying these sequences typically relies on comparisons with sequences from genetic databases, particularly GenBank. While concerns have been raised about biases and inaccuracies in laboratory and analytical methods, comparatively little attention has been paid to the taxonomic reliability of GenBank itself. Here we analyze the metazoan mitochondrial sequences of GenBank using a combination of distance-based clustering and phylogenetic analysis. Because of their comparatively rapid evolutionary rates and consequent high taxonomic resolution, mitochondrial sequences represent an invaluable resource for the detection of the many small and often undescribed organisms that represent the bulk of animal diversity. We show that metazoan identifications in GenBank are surprisingly accurate, even at low taxonomic levels (likely <1% error rate at the genus level). This stands in contrast to previously voiced concerns based on limited analyses of particular groups and the fact that individual researchers currently submit annotated sequences to GenBank without significant external taxonomic validation. Our encouraging results suggest that the rapid uptake of DNA-based approaches is supported by a bioinformatic infrastructure capable of assessing both the losses to biodiversity caused by global change and the effectiveness of conservation efforts aimed at slowing or reversing these losses.
Hearing loss mutations alter the functional properties of human P2X2 receptor channels through distinct mechanisms
Authors: George Benjamin , Swartz Kenton J. , Li Mufeng
Published: October 2019

Significance

In the cochlea, extracellular ATP-activated P2X2 receptor channels play important roles in adaptation to elevated sound, and several hP2X2 mutations cause inherited progressive sensorineural hearing loss. We investigated the functional properties of 3 mutants (V60L, D273Y, and G353R) and show that only the D273Y mutant results in nonfunctional channels. The V60L mutant exhibits constitutive activation and uncoupling between ATP binding and pore opening, while the G353R mutant exhibits altered sensitivity to ATP, inward rectification, and ion selectivity. Our results demonstrate that mutations in P2X2 receptors can cause hearing loss without completely disrupting channel function, highlighting the importance of these channels for protecting hearing.
Developmental competence and antigen switch frequency can be uncoupled in
Trypanosoma brucei
Authors: McWilliam Kirsty R. , Ivens Alasdair , Morrison Liam J. , Mugnier Monica R. , Matthews Keith R.
Published: October 2019

African trypanosomes use an extreme form of antigenic variation to evade host immunity, involving the switching of expressed variant surface glycoproteins by a stochastic and parasite-intrinsic process. Parasite development in the mammalian host is another feature of the infection dynamic, with trypanosomes undergoing quorum sensing (QS)-dependent differentiation between proliferative slender forms and arrested, transmissible, stumpy forms. Longstanding experimental studies have suggested that the frequency of antigenic variation and transmissibility may be linked, antigen switching being higher in developmentally competent, fly-transmissible, parasites (“pleomorphs”) than in serially passaged “monomorphic” lines that cannot transmit through flies. Here, we have directly tested this tenet of the infection dynamic by using 2 experimental systems to reduce pleomorphism. Firstly, lines were generated that inducibly lose developmental capacity through RNAi-mediated silencing of the QS signaling machinery (“inducible monomorphs”). Secondly, de novo lines were derived that have lost the capacity for stumpy formation by serial passage (“selected monomorphs”) and analyzed for their antigenic variation in comparison to isogenic preselected populations. Analysis of both inducible and selected monomorphs has established that antigen switch frequency and developmental capacity are independently selected traits. This generates the potential for diverse infection dynamics in different parasite populations where the rate of antigenic switching and transmission competence are uncoupled. Further, this may support the evolution, maintenance, and spread of important trypanosome variants such as
Trypanosoma brucei evansi
that exploit mechanical transmission.
“Context collapse” on a small island
Authors: Moore Robert
Published: October 2019

Commentators and analysts in new media studies have taken inspiration from Goffman’s ‘dramaturgical’ approach to interaction as performance, as well as his concepts of ‘face’ and ‘impression management’. Goffman is specifically invoked in discussions of a particular source of interactional trouble that is seen as generated in and by the structure of mediated communication in digital spaces: so-called “context collapse.” Context collapse represents “a crisis of self-presentation” (Wesch, 2008) that is brought about by the ability of digital platforms like Twitter and Facebook to “flatten multiple audiences into one” (Marwick & boyd, 2010, p. 9). Returning to Goffman’s unpublished PhD dissertation (Goffman, 1953) – based on fieldwork on the remote island of Unst in the Shetlands – presents an opportunity to understand more fully both the online phenomenon of “context collapse” and the promise and limitations of Goffman’s work for the study of interaction in digital environments.
Digital media communication, intellectual property, and the commodification of language
Authors: Park Joseph Sung-Yul
Published: October 2019

Focusing on fansubbing, the production of unauthorized subtitles by fans of audiovisual media content, this paper calls for a more serious sociolinguistic analysis of the political economy of digital media communication. It argues that fansubbing’s contentious position within regimes of intellectual property and copyright makes it a useful context for considering the crucial role of language ideology in global capitalism’s expanding reach over communicative activity. Through a critical analysis of Korean discourses about fansubbing, this paper considers how tensions between competing ideological conceptions of fansub work shed light on the process by which regimes of intellectual property incorporate digital media communication as a site for profit. Based on this analysis, the paper argues for the need to look beyond the affordances of digital media in terms of translingual, hybrid, and creative linguistic form, to extend our investigations towards language ideologies as a constitutive element in the political economy.
DNA oligomer binding in competition exhibits cooperativity
Authors: Mohammadi-Kambs Mina , Ott Albrecht
Published: October 2019

Binding of two complementary DNA single strands to a double-helix, DNA hybridization, is a sequence specific molecular recognition process that plays important roles in biology and biotechnological applications. In the past much work has been devoted to understand double helix formation, however, DNA binding in complex situations often remains difficult to deal with. Here we use fluorescence anisotropy to assess the binding affinities of DNA oligonucleotide strands that compete for hybridization to the same probe molecule in thermal equilibrium. We find that the ratio of the binding constants in competition can change substantially compared to pairwise assessments. This is a signature of non-trivial interaction among the competitors: the binding microstates of each strand are affected by the presence of the other, but to a different degree. To our knowledge this type of phenomenon is not included in current equilibrium models of oligonucleotide binding. We suggest interactions beyond double helix conformations to cause the observed cooperative behavior. The cooperativity could produce more complex binding phenomena than previously thought.
Data-driven inference of physical devices: theory and implementation
Authors: Buscemi Francesco , Dall’Arno Michele
Published: October 2019

Given a physical device as a black box, one can in principle fully reconstruct its input–output transfer function by repeatedly feeding different input probes through the device and performing different measurements on the corresponding outputs. However, for such a complete tomographic reconstruction to work, full knowledge of both input probes and output measurements is required. Such an assumption is not only experimentally demanding, but also logically questionable, as it produces a circular argument in which the characterization of unknown devices appears to require other devices to have been already characterized beforehand. Here, we introduce a method to overcome such limitations present in usual tomographic techniques. We show that, even without any knowledge about the tomographic apparatus, it is still possible to infer the unknown device to a high degree of precision, solely relying on the observed data. This is achieved by employing a criterion that singles out the minimal explanation compatible with the observed data. Our method, that can be seen as a data-driven analog of tomography, is solved analytically and implemented as an algorithm for the learning of qubit channels.
Vegetation, rainfall, and pulsing hydrology in the Pantanal, the world’s largest tropical wetland
Authors: Ivory Sarah J , McGlue Michael M , Spera Stephanie , Silva Aguinaldo , Bergier Ivan
Published: October 2019

Wetlands provide valuable ecosystem services and play a central role in global carbon cycling. Changes in rainfall and the flood-pulse are likely to disrupt the processes that maintain these landscapes; further, landscape modification may dramatically alter wetlands and promote terrestrialization. The Pantanal, South America, is the world’s largest wetland due to flooding along the Upper Paraguay River. Predicting how water resources in the Pantanal may change is problematic due to a complex drainage network, resulting in the out-of-phase timing of rainfall and the flood pulse. We use remote sensing data of vegetation and climate to better understand the relationships among the rains, the flood pulse, and vegetation. Although rainfall is regionally synchronous, vegetation responses differ based on position relative to inundated areas. Away from rivers, vegetation greening occurs immediately following rainfall. Along channels, greening may lag rainfall by six months, responding closely to local flood stage. Interannual rainfall variability also impacts vegetation differently near flooded areas, with weaker, lagged responses to rainfall due to local water storage. This work suggests that the importance of flood pulse timing for vegetation productivity in inundated areas means that local conditions in wetlands may be the strongest controls on biogeochemical processes.
Multiscale trends and precipitation extremes in the Central American Midsummer Drought
Authors: Anderson Talia G , Anchukaitis Kevin J , Pons Diego , Taylor Matthew
Published: October 2019

Anecdotal evidence suggests that the timing and intensity of the Central American Midsummer Drought (MSD) may be changing, while observations from limited meteorological station data and paleoclimate reconstructions show neither significant nor consistent trends in seasonal rainfall. Climate model simulations project robust future drying across the region, but internal variability is expected to dominate until the end of the century. Here we use a high-resolution gridded precipitation dataset to investigate these apparent discrepancies and to quantify the spatiotemporal complexities of the MSD. We detect spatially variable trends in MSD timing, the amount of rainy season precipitation, the number of consecutive and total dry days, and extreme wet events at the local scale. At the regional scale, we find a positive trend in the duration, but not the magnitude of the MSD, which is dominated by spatially heterogeneous trends and interannual variability linked to large-scale modes of ocean-atmosphere circulation. Although the current climate still reflects predominantly internal variability, some Central American communities are already experiencing significant changes in local characteristics of the MSD. A detailed spatiotemporal understanding of MSD trends and variability can contribute to evidence-based adaptation planning and help reduce the vulnerability of Central American communities to both natural rainfall variability and anthropogenic change.
A green infrastructure spatial planning model for evaluating ecosystem service tradeoffs and synergies across three coastal megacities
Authors: Meerow Sara
Published: October 2019

A growing number of cities are investing in green infrastructure to foster urban resilience and sustainability. While these nature-based solutions are often promoted on the basis of their multifunctionality, in practice, most studies and plans focus on a single benefit, such as stormwater management. This represents a missed opportunity to strategically site green infrastructure to leverage social and ecological co-benefits. To address this gap, this paper builds on existing modeling approaches for green infrastructure planning to create a more generalizable tool for comparing spatial tradeoffs and synergistic ‘hotspots’ for multiple desired benefits. I apply the model to three diverse coastal megacities: New York City, Los Angeles (United States), and Manila (Philippines), enabling cross-city comparisons for the first time. Spatial multi-criteria evaluation is used to examine how strategic areas for green infrastructure development across the cities change depending on which benefit is prioritized. GIS layers corresponding to six planning priorities (managing stormwater, reducing social vulnerability, increasing access to green space, improving air quality, reducing the urban heat island effect, and increasing landscape connectivity) are mapped and spatial tradeoffs assessed. Criteria are also weighted to reflect local stakeholders’ desired outcomes as determined through surveys and stakeholder meetings and combined to identify high priority areas for green infrastructure development. To extend the model’s utility as a decision-support tool, an interactive web-based application is developed that allows any user to change the criteria weights and visualize the resulting hotspots in real time. The model empirically illustrates the complexities of planning green infrastructure in different urban contexts, while also demonstrating a flexible approach for more participatory, strategic, and multifunctional planning of green infrastructure in cities around the world.
Escaping from pollution: the effect of air quality on inter-city population mobility in China
Authors: Cui Can , Wang Zhen , He Pan , Yuan Shanfeng , Niu Beibei , Kang Ping , Kang Chaogui
Published: October 2019

China faces severe air pollution issues due to the rapid growth of the economy, causing concerns for human physical and mental health as well as behavioral changes. Such adverse impacts can be mediated by individual avoidance behaviors such as traveling from polluted cities to cleaner ones. This study utilizes smartphone-based location data and instrumental variable regression to try and find out how air quality affects population mobility. Our results confirm that air quality does affect the population outflows of cities. An increase of 100 points in the air quality index will cause a 49.60% increase in population outflow, and a rise of 1 μg m−3 in PM2.5 may cause a 0.47% rise in population outflow. Air pollution incidents can drive people to leave their cities 3 days or a week later by railway or road. The effect is heterogeneous among workdays, weekends and holidays. Our results imply that air quality management can be critical for urban tourism and environmental competitiveness.
Multi-year prediction of European summer drought conditions for the agricultural sector
Authors: Solaraju-Murali Balakrishnan , Caron Louis-Philippe , Gonzalez-Reviriego Nube , Doblas-Reyes Francisco J
Published: October 2019

Decadal climate prediction, where climate models are initialized with the contemporaneous state of the Earth system and run for a decade into the future, represents a new source of near-term climate information to better inform decisions and policies across key climate-sensitive sectors. This paper illustrates the potential usefulness of such predictions for building a climate service for agricultural needs. In particular, we assess the forecast quality of multi-model climate predictions in estimating two user-relevant drought indices, Standardized Precipitation Evapotranspiration Index (SPEI) and Standardized Precipitation Index (SPI), at multi-annual timescales during European summer. We obtain high skill for predicting five-year average (forecast years 1–5) SPEI across Southern Europe, while for the same forecast period SPI exhibits high and significant skill over Scandinavia and its surrounding regions. In addition, an assessment of the added value of initialized decadal climate information with respect to standard uninitialized climate projections is presented. The model initialization improves the forecast skill over Central Europe, the Balkan region and Southern Scandinavia. Most of the increased skill found with initialization seems to be due to the climate forecast systems ability to improve the extended summer precipitation and potential evapotranspiration forecast, as well as their ability to adequately represent the observed effects of these climate variables on the drought indices.
The aridity Index under global warming
Authors: Greve P , Roderick M L , Ukkola A M , Wada Y
Published: October 2019

Aridity is a complex concept that ideally requires a comprehensive assessment of hydroclimatological and hydroecological variables to fully understand anticipated changes. A widely used (offline) impact model to assess projected changes in aridity is the aridity index (AI) (defined as the ratio of potential evaporation to precipitation), summarizing the aridity concept into a single number. Based on the AI, it was shown that aridity will generally increase under conditions of increased CO2 and associated global warming. However, assessing the same climate model output directly suggests a more nuanced response of aridity to global warming, raising the question if the AI provides a good representation of the complex nature of anticipated aridity changes. By systematically comparing projections of the AI against projections for various hydroclimatological and ecohydrological variables, we show that the AI generally provides a rather poor proxy for projected aridity conditions. Direct climate model output is shown to contradict signals of increasing aridity obtained from the AI in at least half of the global land area with robust change. We further show that part of this discrepancy can be related to the parameterization of potential evaporation. Especially the most commonly used potential evaporation model likely leads to an overestimation of future aridity due to incorrect assumptions under increasing atmospheric CO2. Our results show that AI-based approaches do not correctly communicate changes projected by the fully coupled climate models. The solution is to directly analyse the model outputs rather than use a separate offline impact model. We thus urge for a direct and joint assessment of climate model output when assessing future aridity changes rather than using simple index-based impact models that use climate model output as input and are potentially subject to significant biases.
The role of simulation in preventing indoor air pollution: a foregone conclusion?
Authors: Lv Mengqiang , Yang Xudong
Published: October 2019

Indoor air pollution has become a broad problem due to various indoor or outdoor pollutant sources and limited ventilation. A performance-based approach, which is built upon accurate modelling and simulation of indoor air pollutant characteristics, has obvious advantages over the prescription-based method to achieve better indoor environment. Moreover, the simulation could play a key role in actively preventing indoor air pollution from happening in the first place. In this study, a mechanistic air quality simulation tool was introduced. To verify the reliability of simulation results, two actual field cases with different levels of complexity and time duration were discussed. One was performed in a full-scale experimental room with a single formaldehyde source of a medium density board, in which indoor formaldehyde concentrations varied naturally. Long-term (more than three years) comparison between the simulation results and measurement were conducted. Another occurred during the decoration process in an actual apartment. The formaldehyde concentration levels were well predicted at the design stage and later verified by the field data. Nevertheless, a lot more efforts are required to make indoor air quality (IAQ) simulation tools readily useful in actual engineering applications.