500 research outputs found

    Emulated nuclear spin gyroscope with 15^{15}NV centers in diamond

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    Nuclear spins in solid-state platforms are promising for building rotation sensors due to their long coherence times. Among these platforms, nitrogen-vacancy centers have attracted considerable attention with ambient operating conditions. However, the current performance of NV gyroscopes remains limited by the degraded coherence when operating with large spin ensembles. Protecting the coherence of these systems requires a systematic study of the coherence decay mechanism. Here we present the use of nitrogen-15 nuclear spins of NV centers in building gyroscopes, benefiting from its simpler energy structure and vanishing nuclear quadrupole term compared with nitrogen-14 nuclear spins, though suffering from different challenges in coherence protection. We systematically reveal the coherence decay mechanism of the nuclear spin in different NV electronic spin manifolds and further develop a robust coherence protection protocol based on controlling the NV electronic spin only, achieving a 15-fold dephasing time improvement. With the developed coherence protection, we demonstrate an emulated gyroscope by measuring a designed rotation rate pattern, showing an order-of-magnitude sensitivity improvement

    Cerebrospinal fluid neopterin: an informative biomarker of central nervous system immune activation in HIV-1 infection

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    HIV-1 invades the central nervous system (CNS) in the context of acute infection, persists thereafter in the absence of treatment, and leads to chronic intrathecal immunoactivation that can be measured by the macrophage activation marker, neopterin, in cerebrospinal fluid (CSF). In this review we describe our experience with CSF neopterin measurements in 382 untreated HIV-infected patients across the spectrum of immunosuppression and HIV-related neurological diseases, in 73 untreated AIDS patients with opportunistic CNS infections, and in 233 treated patients

    Assembly of functional diversity in an oceanic island flora

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    Oceanic island floras are well known for their morphological peculiarities and exhibit striking examples of trait evolution1–3. These morphological shifts are commonly attributed to insularity and are thought to be shaped by the biogeographical processes and evolutionary histories of oceanic islands2,4. However, the mechanisms through which biogeography and evolution have shaped the distribution and diversity of plant functional traits remain unclear5. Here we describe the functional trait space of the native flora of an oceanic island (Tenerife, Canary Islands, Spain) using extensive field and laboratory measurements, and relate it to global trade-offs in ecological strategies. We find that the island trait space exhibits a remarkable functional richness but that most plants are concentrated around a functional hotspot dominated by shrubs with a conservative life-history strategy. By dividing the island flora into species groups associated with distinct biogeographical distributions and diversification histories, our results also suggest that colonization via long-distance dispersal and the interplay between inter-island dispersal and archipelago-level speciation processes drive functional divergence and trait space expansion. Contrary to our expectations, speciation via cladogenesis has led to functional convergence, and therefore only contributes marginally to functional diversity by densely packing trait space around shrubs. By combining biogeography, ecology and evolution, our approach opens new avenues for trait-based insights into how dispersal, speciation and persistence shape the assembly of entire native island floras.Fil: Barajas Barbosa, Martha Paola. Martin-luther-Universität Halle-Wittenberg; Alemania. German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; Alemania. Universität Göttingen; AlemaniaFil: Craven, Dylan. Data Observatory Foundation; Chile. Universidad Mayor; ChileFil: Weigelt, Patrick. Universität Göttingen; AlemaniaFil: Denelle, Pierre. Universität Göttingen; AlemaniaFil: Otto, Rüdiger. Universidad de La Laguna; EspañaFil: Díaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Price, Jonathan. University Of Hawaii At Hilo; Estados UnidosFil: Fernández Palacios, José María. Universidad de La Laguna; EspañaFil: Kreft, Holger. Universität Göttingen; Alemani

    Unmet clinical needs for COVID-19 tests in UK health and social care settings

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    There is an urgent requirement to identify which clinical settings are in most need of COVID-19 tests and the priority role(s) for tests in these settings to accelerate the development of tests fit for purpose in health and social care across the UK. This study sought to identify and prioritize unmet clinical needs for COVID-19 tests across different settings within the UK health and social care sector via an online survey of health and social care professionals and policymakers. Four hundred and forty-seven responses were received between 22nd May and 15th June 2020. Hospitals and care homes were recognized as the settings with the greatest unmet clinical need for COVID-19 diagnostics, despite reporting more access to laboratory molecular testing than other settings. Hospital staff identified a need for diagnostic tests for symptomatic workers and patients. In contrast, care home staff expressed an urgency for screening at the front door to protect high-risk residents and limit transmission. The length of time to test result was considered a widespread problem with current testing across all settings. Rapid tests for staff were regarded as an area of need across general practice and dental settings alongside tests to limit antibiotics use

    We are 60!

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    Here we are midway in our 60th Anniversary year. Since I last wrote, quite a few things have happened with the journal and AIP Publishing. First, of course, AIP Publishing have signed up to the Declaration on Research Assessment (DORA), aligning well with the mantra which has always been a core principle in Applied Physics Letters (APL)—the quality and clarity of the manuscript, the contribution it makes to the field, and the potential it offers for new applied physics opportunities are key for us—not the immediacy of its impact or trend following. Having said all that, I am proud that the impact factor of the journal continues to increase and that communities of applied physics researchers are discovering or returning to the journal

    GRB010222: afterglow emission from a rapidly decelerating shock

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    The GRB010222 optical and near-infrared (NIR) afterglow was monitored at the TNG and other Italian telescopes starting ~1 day after the high-energy prompt event. The optical BVR light curves, which are the best sampled, are continuously steepening, and can be described by two power laws, f(t) = t^(-alpha), of indices alpha_1 ~ 0.7 and alpha_2 ~ 1.3 before and after a break occurring at about 0.5 days after the GRB start time, respectively. This model accounts well also for the flux in the U, I and J bands, which are less well monitored. The temporal break appears to be achromatic. The two K-band points are not consistent with the above behaviour, and rather suggest a constant trend. A low-resolution optical spectrum has also been taken with TNG. In the optical spectrum we found three absorption systems at different redshifts (0.927, 1.155 and 1.475), the highest of which represents a lower limit to, and probably coincides with, the redshift of this GRB. The broad-band optical spectral energy distributions do not appear to vary with time, consistently with the achromatic behaviour of the light curves. We compare our measurements with different afterglow evolution scenarios and we find that they favor a transition from relativistic to non-relativistic conditions in the shock propagation.Comment: Accepted by Astronomy and Astrophysics; modified according to referee's comments. Two figures added, U-band photometry corrected, hydrodynamic description of the afterglow revised, host galaxy absorption considered, references adde

    Cerebrospinal Fluid Viral Load Across the Spectrum of Untreated Human Immunodeficiency Virus Type 1 (HIV-1) Infection: A Cross-Sectional Multicenter Study

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    Background The aim of this large multicenter study was to determine variations in cerebrospinal fluid (CSF) HIV-RNA in different phases of untreated human immunodeficiency virus type 1 (HIV-1) infection and its associations with plasma HIV-RNA and other biomarkers. Methods Treatment naive adults with available CSF HIV-RNA quantification were included and divided into groups representing significant disease phases. Plasma HIV-RNA, CSF white blood cell count (WBC), neopterin, and albumin ratio were included when available. Results In total, 1018 patients were included. CSF HIV-RNA was in median (interquartile range [IQR]) 1.03 log(10) (0.37-1.86) copies/mL lower than in plasma, and correlated with plasma HIV-RNA (r = 0.44, P < .01), neopterin concentration in CSF (r = 0.49, P < .01) and in serum (r = 0.29, P < .01), CSF WBC (r = 0.34, P < .01) and albumin ratio (r = 0.25, P < .01). CSF HIV-RNA paralleled plasma HIV-RNA in all groups except neuroasymptomatic patients with advanced immunodeficiency (CD4 < 200) and patients with HIV-associated dementia (HAD) or opportunistic central nervous system (CNS) infections. Patients with HAD had the highest CSF HIV-RNA (in median [IQR] 4.73 (3.84-5.35) log(10) copies/mL). CSF > plasma discordance was found in 126 of 972 individuals (13%) and varied between groups, from 1% in primary HIV, 11% in neuroasymptomatic groups, up to 30% of patients with HAD. Conclusions Our study confirms previous smaller observations of variations in CSF HIV-RNA in different stages of HIV disease. Overall, CSF HIV-RNA was approximately 1 log(10) copies/mL lower in CSF than in plasma, but CSF discordance was found in a substantial minority of subjects, most commonly in patients with HAD, indicating increasing CNS compartmentalization paralleling disease progression. HIV-RNA is detectable in cerebrospinal fluid (CSF) across all stages of untreated HIV and usually parallel plasma HIV-RNA at a lower level. A substantial proportion (13%) of patients have CSF>plasma HIV-RNA, most commonly in patients with HIV-associated dementia
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