132 research outputs found
Prey Selection and Bioenergetics of Captive Screech Owls
Author Institution: Department of Zoology and Institute of Environmental Sciences, Miami UniversityScreech owls appeared to select meadow voles {Microtus pennsylvanicus) as a primary food source, although deer mice (Peromyscus maniculatus) were apparently equally abundant and vulnerable. This feeding behavior resulted in a larger energy reward. A mean ingestion rate of 0.37 kcal/g live wt/day was derived from average values of 29-3 g live wt/day for Microtus as prey and only 11.3 g live wt/day for Peromyscus. Assimilation energy (ingestion-pellets-feces) was 0.28 kcal/g live wt/day; the mean assimilation efficiency (ingested energy-pellet energy-fecal energy/ingested energy x 100) was 76%. These findings support the hypothesis that a large energy reward is a prime factor in prey selection
Cross-verification of independent quantum devices
Quantum computers are on the brink of surpassing the capabilities of even the
most powerful classical computers. This naturally raises the question of how
one can trust the results of a quantum computer when they cannot be compared to
classical simulation. Here we present a verification technique that exploits
the principles of measurement-based quantum computation to link quantum
circuits of different input size, depth, and structure. Our approach enables
consistency checks of quantum computations within a device, as well as between
independent devices. We showcase our protocol by applying it to five
state-of-the-art quantum processors, based on four distinct physical
architectures: nuclear magnetic resonance, superconducting circuits, trapped
ions, and photonics, with up to 6 qubits and 200 distinct circuits
Cryogenic setup for trapped ion quantum computing
We report on the design of a cryogenic setup for trapped ion quantum
computing containing a segmented surface electrode trap. The heat shield of our
cryostat is designed to attenuate alternating magnetic field noise, resulting
in 120~dB reduction of 50~Hz noise along the magnetic field axis. We combine
this efficient magnetic shielding with high optical access required for single
ion addressing as well as for efficient state detection by placing two lenses
each with numerical aperture 0.23 inside the inner heat shield. The cryostat
design incorporates vibration isolation to avoid decoherence of optical qubits
due to the motion of the cryostat. We measure vibrations of the cryostat of
less than 20~nm over 2~s. In addition to the cryogenic apparatus, we
describe the setup required for an operation with
Ca and Sr ions.
The instability of the laser manipulating the optical qubits in
Ca is characterized yielding a minimum of its
Allan deviation of 2.410 at 0.33~s. To evaluate the
performance of the apparatus, we trapped Ca
ions, obtaining a heating rate of 2.14(16)~phonons/s and a Gaussian decay of
the Ramsey contrast with a 1/e-time of 18.2(8)~ms
Verifiable measurement-based quantum random sampling with trapped ions
Quantum computers are now on the brink of outperforming their classical counterparts. One way to demonstrate the advantage of quantum computation is through quantum random sampling performed on quantum computing devices. However, existing tools for verifying that a quantum device indeed performed the classically intractable sampling task are either impractical or not scalable to the quantum advantage regime. The verification problem thus remains an outstanding challenge. Here, we experimentally demonstrate efficiently verifiable quantum random sampling in the measurement-based model of quantum computation on a trapped-ion quantum processor. We create and sample from random cluster states, which are at the heart of measurement-based computing, up to a size of 4 × 4 qubits. By exploiting the structure of these states, we are able to recycle qubits during the computation to sample from entangled cluster states that are larger than the qubit register. We then efficiently estimate the fidelity to verify the prepared states—in single instances and on average—and compare our results to cross-entropy benchmarking. Finally, we study the effect of experimental noise on the certificates. Our results and techniques provide a feasible path toward a verified demonstration of a quantum advantage
Experimental deterministic correction of qubit loss
The successful operation of quantum computers relies on protecting qubits from decoherence and noise which, if uncorrected, will lead to erroneous results. These errors accumulate during an algorithm and thus correcting them becomes a key requirement for large-scale and fault-tolerant quantum information processors. Besides computational errors, which can be addressed by quantum error correction, the carrier of the information can also be completely lost or the information can leak out of the computational space. It is expected that such loss errors will occur at rates that are comparable to computational errors. Here we experimentally implement a full cycle of qubit loss detection and correction on a minimal instance of a topological surface code in a trapped-ion quantum processor. The key technique for this correction is a quantum non-demolition measurement via an ancillary qubit, which acts as a minimally invasive probe to detect absent qubits while only imparting the minimal quantum-mechanically possible disturbance on the remaining qubits. Upon detecting qubit loss, a recovery procedure is triggered in real-time, which maps the logical information onto a new encoding on the remaining qubits. Although the current demonstration is performed in a trapped-ion quantum processor, the protocol is applicable to other quantum computing architectures and error correcting codes, including leading 2D and 3D topological codes. These methods provide a complete toolbox for the correction of qubit loss that complements techniques to mitigate computational errors, which together constitute the building blocks for complete and scalable quantum error correction
Evidence for predilection of macrophage infiltration patterns in the deeper midline and mesial temporal structures of the brain uniquely in patients with HIV-associated dementia
<p>Abstract</p> <p>Background</p> <p>HIV-1 penetrates the central nervous system, which is vital for HIV-associated dementia (HAD). But the role of cellular infiltration and activation together with HIV in the development of HAD is poorly understood.</p> <p>Methods</p> <p>To study activation and infiltration patterns of macrophages, CD8+ T cells in relation to HIV in diverse CNS areas of patients with and without dementia. 46 brain regions from two rapidly progressing severely demented patients and 53 regions from 4 HIV+ non-dementia patients were analyzed. Macrophage and CD8+ T cell infiltration of the CNS in relation to HIV was assessed using immuno-histochemical analysis with anti-HIV (P24), anti-CD8 and anti-CD68, anti-S-100A8 and granzyme B antibodies (cellular activation). Statistical analysis was performed with SPSS 12.0 with Student's t test and ANOVA.</p> <p>Results</p> <p>Overall, the patterns of infiltration of macrophages and CD8+ T cells were indiscernible between patients with and without dementia, but the co-localization of macrophages and CD8+ T cells along with HIV P24 antigen in the deeper midline and mesial temporal structures of the brain segregated the two groups. This predilection of infected macrophages and CD8+ T cells to the middle part of the brain was unique to both HAD patients, along with unique nature of provirus gag gene sequences derived from macrophages in the midline and mesial temporal structures.</p> <p>Conclusion</p> <p>Strong predilection of infected macrophages and CD8+ T cells was typical of the deeper midline and mesial temporal structures uniquely in HAD patients, which has some influence on neurocognitive impairment during HIV infection.</p
In Absolute or Relative Terms? How Framing Prices Affects the Consumer Price Sensitivity of Health Plan Choice
This paper provides field evidence on (a) how price framing affects consumers' decision to switch health insurance plans and (b) how the price elasticity of demand for health insurance can be influenced by policymakers through simple regulatory efforts. In 2009, in order to foster competition among health insurance companies, German federal regulation required health insurance companies to express price differences between health plans in absolute Euro values rather than percentage point payroll tax differences. Using individual-level panel data, as well as aggregated health plan-level panel data, we find that the reform led to a sixfold increase in an individual's switching probability and a threefold demand elasticity increase
Experimental measurement and a physical interpretation of quantum shadow enumerators
Throughout its history, the theory of quantum error correction has heavily benefited from translating classical concepts into the quantum setting. In particular, classical notions of weight enumerators, which relate to the performance of an error-correcting code, and MacWilliams\u27 identity, which helps to compute enumerators, have been generalized to the quantum case. In this work, we establish a distinct relationship between the theoretical machinery of quantum weight enumerators and a seemingly unrelated physics experiment: we prove that Rains\u27 quantum shadow enumerators - a powerful mathematical tool - arise as probabilities of observing fixed numbers of triplets in a Bell sampling experiment. This insight allows us to develop here a rigorous framework for the direct measurement of quantum weight enumerators, thus enabling experimental and theoretical studies of the entanglement structure of any quantum error-correcting code or state under investigation. On top of that, we derive concrete sample complexity bounds and physically-motivated robustness guarantees against unavoidable experimental imperfections. Finally, we experimentally demonstrate the possibility of directly measuring weight enumerators on a trapped-ion quantum computer. Our experimental findings are in good agreement with theoretical predictions and illuminate how entanglement theory and quantum error correction can cross-fertilize each other once Bell sampling experiments are combined with the theoretical machinery of quantum weight enumerators.21+12 pages, 6+7 figure
Elevated circulating levels of succinate in human obesity are linked to specific gut microbiota
Gut microbiota-related metabolites are potential clinical biomarkers for cardiovascular disease (CVD). Circulating succinate, a metabolite produced by both microbiota and the host, is increased in hypertension, ischemic heart disease, and type 2 diabetes. We aimed to analyze systemic levels of succinate in obesity, a major risk factor for CVD, and its relationship with gut microbiome. We explored the association of circulating succinate with specific metagenomic signatures in cross-sectional and prospective cohorts of Caucasian Spanish subjects. Obesity was associated with elevated levels of circulating succinate concomitant with impaired glucose metabolism. This increase was associated with specific changes in gut microbiota related to succinate metabolism: a higher relative abundance of succinate-producing Prevotellaceae (P) and Veillonellaceae (V), and a lower relative abundance of succinate-consuming Odoribacteraceae (O) and Clostridaceae (C) in obese individuals, with the (P + V/O + C) ratio being a main determinant of plasma succinate. Weight loss intervention decreased (P + V/O + C) ratio coincident with the reduction in circulating succinate. In the spontaneous evolution after good dietary advice, alterations in circulating succinate levels were linked to specific metagenomic signatures associated with carbohydrate metabolism and energy production with independence of body weight change. Our data support the importance of microbe-microbe interactions for the metabolite signature of gut microbiome and uncover succinate as a potential microbiota-derived metabolite related to CVD risk
2021 Taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales.
Correction to: 2021 Taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales. Archives of Virology (2021) 166:3567–3579. https://doi.org/10.1007/s00705-021-05266-wIn March 2021, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by four families (Aliusviridae, Crepuscuviridae, Myriaviridae, and Natareviridae), three subfamilies (Alpharhabdovirinae, Betarhabdovirinae, and Gammarhabdovirinae), 42 genera, and 200 species. Thirty-nine species were renamed and/or moved and seven species were abolished. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.This work was supported in part through Laulima Government Solutions, LLC prime contract with the US National Institute of Allergy and Infectious Diseases (NIAID) under Contract No. HHSN272201800013C. J.H.K. performed this work as an employee of Tunnell Government Services (TGS), a subcontractor of Laulima Government Solutions, LLC under Contract No. HHSN272201800013C. This work was also supported in part with federal funds from the National Cancer Institute (NCI), National Institutes of Health (NIH), under Contract No. 75N91019D00024, Task Order No. 75N91019F00130 to I.C., who was supported by the Clinical Monitoring Research Program Directorate, Frederick National Lab for Cancer Research. This work was also funded in part by Contract No. HSHQDC-15-C-00064 awarded by DHS S&T for the management and operation of The National Biodefense Analysis and Countermeasures Center, a federally funded research and development center operated by the Battelle National Biodefense Institute (V.W.); and NIH contract HHSN272201000040I/HHSN27200004/D04 and grant R24AI120942 (N.V., R.B.T.). S.S. acknowledges partial support from the Special Research Initiative of Mississippi Agricultural and Forestry Experiment Station (MAFES), Mississippi State University, and the National Institute of Food and Agriculture, US Department of Agriculture, Hatch Project 1021494. Part of this work was supported by the Francis Crick Institute which receives its core funding from Cancer Research UK (FC001030), the UK Medical Research Council (FC001030), and the Wellcome Trust (FC001030).S
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