836 research outputs found
Toward physical realizations of thermodynamic resource theories
Conventional statistical mechanics describes large systems and averages over
many particles or over many trials. But work, heat, and entropy impact the
small scales that experimentalists can increasingly control, e.g., in
single-molecule experiments. The statistical mechanics of small scales has been
quantified with two toolkits developed in quantum information theory: resource
theories and one-shot information theory. The field has boomed recently, but
the theorems amassed have hardly impacted experiments. Can thermodynamic
resource theories be realized experimentally? Via what steps can we shift the
theory toward physical realizations? Should we care? I present eleven
opportunities in physically realizing thermodynamic resource theories.Comment: Publication information added. Cosmetic change
Highly Oxygenated Flavonoids from the Leaves of Nicotiana plumbaginifolia (Solanaceae)
Nicotiana plumbaginifolia Viv. is an annual herb of the family Solanaceae, which grows abundantly in the weedy lands of Bangladesh. This plant possesses analgesic, antibacterial, anti-anxiety and hepatoprotective properties, and produces various phenolic compounds including flavonoids. The present study afforded determination of total phenolic and flavonoid contents, and for the first time, the isolation and characterization of highly oxygenated flavonoids, e.g., 3,3',5,6,7,8-hexamethoxy-4',5'-methylenedioxyflavone (1), 3,3',4',5',5,6,7,8-octamethoxyflavone (2, exoticin), 6,7,4',5'-dimethylenedioxy-3,5,3'-trimethoxyflavone (3) and (3,3',4',5,5',8-hexamethoxy-6,7-methylenedioxyflavone (4) from the leaves of N. plumbaginifolia. All these flavonoids are rather rare natural products, and only found in a few genera, e.g., Polygonum and Murraya. The structures of the isolated flavonoids were elucidated by comprehensive spectroscopic analyses, e.g., UV, 1H, 13C NMR, DEPT, HSQC, HMBC and MS
Measurement of Rashba and Dresselhaus spin-orbit magnetic fields
Spin-orbit coupling is a manifestation of special relativity. In the
reference frame of a moving electron, electric fields transform into magnetic
fields, which interact with the electron spin and lift the degeneracy of
spin-up and spin-down states. In solid-state systems, the resulting spin-orbit
fields are referred to as Dresselhaus or Rashba fields, depending on whether
the electric fields originate from bulk or structure inversion asymmetry,
respectively. Yet, it remains a challenge to determine the absolute value of
both contributions in a single sample. Here we show that both fields can be
measured by optically monitoring the angular dependence of the electrons' spin
precession on their direction of movement with respect to the crystal lattice.
Furthermore, we demonstrate spin resonance induced by the spin-orbit fields. We
apply our method to GaAs/InGaAs quantum-well electrons, but it can be used
universally to characterise spin-orbit interactions in semiconductors,
facilitating the design of spintronic devices
Spin-injection Hall effect in a planar photovoltaic cell
Successful incorporation of the spin degree of freedom in semiconductor
technology requires the development of a new paradigm allowing for a scalable,
non-destructive electrical detection of the spin-polarization of injected
charge carriers as they propagate along the semiconducting channel. In this
paper we report the observation of a spin-injection Hall effect (SIHE) which
exploits the quantum-relativistic nature of spin-charge transport and which
meets all these key requirements on the spin detection. The two-dimensional
electron-hole gas photo-voltaic cell we designed to observe the SIHE allows us
to develop a quantitative microscopic theory of the phenomenon and to
demonstrate its direct application in optoelectronics. We report an
experimental realization of a non-magnetic spin-photovoltaic effect via the
SIHE, rendering our device an electrical polarimeter which directly converts
the degree of circular polarization of light to a voltage signal.Comment: 14 pages, 4 figure
Higher Dimensional Cylindrical or Kasner Type Electrovacuum Solutions
We consider a D dimensional Kasner type diagonal spacetime where metric
functions depend only on a single coordinate and electromagnetic field shares
the symmetries of spacetime. These solutions can describe static cylindrical or
cosmological Einstein-Maxwell vacuum spacetimes. We mainly focus on
electrovacuum solutions and four different types of solutions are obtained in
which one of them has no four dimensional counterpart. We also consider the
properties of the general solution corresponding to the exterior field of a
charged line mass and discuss its several properties. Although it resembles the
same form with four dimensional one, there is a difference on the range of the
solutions for fixed signs of the parameters. General magnetic field vacuum
solution are also briefly discussed, which reduces to Bonnor-Melvin magnetic
universe for a special choice of the parameters. The Kasner forms of the
general solution are also presented for the cylindrical or cosmological cases.Comment: 16 pages, Revtex. Text and references are extended, Published versio
GC–MS analysis and pharmacological evaluations of Phoenix sylvestris (Roxb.) seeds provide new insights into the management of oxidative stress and hyperglycemia
Phoenix sylvestris Roxb. (Arecaceae) seeds are used in the treatment of diabetes in the traditional system of medicine. The present study evaluated antihyperglycemic and antioxidant activities as well as the total phenolic and flavonoid content of the methanol extract of P. sylvestris seeds (MEPS). The constituents of the extract were identified by GC–MS analysis. MEPS demonstrated strong antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC50 = 162.70 ± 14.99 μg) and nitric oxide (NO) (IC50 = 101.56 ± 9.46 μg/ml) free radicals. It also possesses a substantial amount of phenolics and flavonoids. It significantly (p < .05) reduced blood glucose levels in glucose-loaded and alloxan-induced diabetic mice at the doses of 150 and 300 mg/kg b.w., respectively. A total of 46 compounds were detected and identified by gas chromatography–mass spectroscopy (GC–MS) analysis, among which 8-methylisoquinoline N-oxide (32.82%) was predominant. The phytochemical study by GC–MS revealed that the MEPS possesses compounds which could be related to its antidiabetic and antioxidant activities. To recapitulate, P. sylvestris seeds can be a very good option for antidiabetic and antioxidant activity though further studies are still recommended to figure out the responsible phytochemicals and establish their exact mechanism of action
A generic anti-QCD jet tagger
New particles beyond the Standard Model might be produced with a very high
boost, for instance if they result from the decay of a heavier particle. If the former decay
hadronically, then their signature is a single massive fat jet which is di cult to separate
from QCD backgrounds. Jet substructure and machine learning techniques allow for the
discrimination of many speci c boosted objects from QCD, but the scope of possibilities is
very large, and a suite of dedicated taggers may not be able to cover every possibility | in
addition to making experimental searches cumbersome. In this paper we describe a generic
model-independent tagger that is able to discriminate a wide variety of hadronic boosted
objects from QCD jets using N-subjettiness variables, with a signi cance improvement
varying between 2 and 8. This is in addition to any improvement that might come from a
cut on jet mass. Such a tagger can be used in model-independent searches for new physics
yielding fat jets. We also show how such a tagger can be applied to signatures over a wide
range of jet masses without sculpting the background distributions, allowing to search for
new physics as bumps on jet mass distributions.The work of JAAS is supported by MINECO Projects FPA 2016-78220-C3-1-P and FPA
2013-47836-C3-2-P (including ERDF), and by Junta de Andalucía Project FQM-101. The
work of JHC and RKM is supported by NSF under Grant No. PHY-1620074 and by the
Maryland Center for Fundamental Physics (MCFP)
Study protocol of the iMPaCT project : A longitudinal cohort study assessing psychological determinants, sexual behaviour and chlamydia (re)infections in heterosexual STI clinic visitors
Acknowledgements We are grateful to the staff at the STI clinics of Amsterdam, Kennemerland, Hollands Noorden, Twente, who are involved in the recruitment and data collection of participants, and Marlous Ratten and Klazien Visser from Soapoli-online, who are involved in the coordination of laboratory testing of the home-based sampling kits at six-month follow-up. We also thank the staff at the STI department at the National Institute for Public Health and the Environment, especially Birgit van Benthem. Funding This project is funded by the Strategic Programme (SPR) of the National Institute for Public Health and the Environment (RIVM) (project number S/113004/01/IP). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Availability of data and materials The dataset (anonymised) generated during this study will be made available for interested parties on request.Peer reviewedPublisher PD
Graphite Epoxy Defect Classification of Ultrasonic Signatures Using Statistical and Neural Network Techniques
The use of graphite epoxy composite materials in thick sections for structural applications in naval vessels is achieving worldwide interest [1]. Current and future applications of composites include construction of hulls, superstructures, weight critical articles, secondary structures and quasi-structural components.</p
- …