Two-dimensional (2D) materials are not expected to be metals at low temperature owing to electron localization1. Consistent with this, pioneering studies on thin lms reported only superconducting and ...insulating ground states, with a direct transition between the two as a function of disorder or magnetic eld26. However, more recent works have revealed the presence of an intermediate quantum metallic state occupying a substantial region of the phase diagram710, whose nature is intensely debated1117. Here, we observe such a state in the disorder-free limit of a crystalline 2D superconductor, produced by mechanical co-lamination of NbSe2 in an inert atmosphere. Under a small perpendicular magnetic eld, we induce a transition from superconductor to the quantum metal. We nd a unique power-law scaling with eld in this phase, which is consistent with the Bose-metal model where metallic behaviour arises from strong phase uctuations caused by the magnetic field1114.
Abstract
The unconventional normal-state properties of the cuprates are often discussed in terms of emergent electronic order that onsets below a putative critical doping of
x
c
≈ 0.19. Charge ...density wave (CDW) correlations represent one such order; however, experimental evidence for such order generally spans a limited range of doping that falls short of the critical value
x
c
, leading to questions regarding its essential relevance. Here, we use X-ray diffraction to demonstrate that CDW correlations in La
2−
x
Sr
x
CuO
4
persist up to a doping of at least
x
= 0.21. The correlations show strong changes through the superconducting transition, but no obvious discontinuity through
x
c
≈ 0.19, despite changes in Fermi surface topology and electronic transport at this doping. These results demonstrate the interaction between CDWs and superconductivity even in overdoped cuprates and prompt a reconsideration of the role of CDW correlations in the high-temperature cuprate phase diagram.
Patients with suspected nephrolithiasis were randomly assigned to ultrasonography performed by an emergency physician or a radiologist or to CT for initial study. Ultrasonography was associated with ...a lower cumulative radiation dose, with no significant difference in complications.
The Bruun rule is the most widely used method for determining shoreline response to sea level rise. It assumes that the active portion of an offshore profile rises with rising sea level, and the sand ...required to raise the profile is transported from the shoreline. It is difficult to evaluate the efficacy of the Bruun rule because sea level rise often has a lesser effect on shoreline change than that produced by sand sources, sinks, and longshore transport gradients. In addition, some shorelines have advanced seaward with rising sea level. Dean (1987) showed that equilibrium profile theory predicts that rising sea levels produce landward sand movement forced by nonlinear waves. This paper presents an equation with terms representing all phenomena affecting shoreline change including Bruun-rule recession, onshore sand transport, sand sources and sinks, and longshore transport gradients. As an example of its use, rates of onshore transport are determined along the 275-km Florida southwest coast, USA, and a 19-km portion of this coast using known values for sand sources, sinks, and longshore transport gradients. Then future shoreline changes are projected for both coasts from 2015 to 2065 and for the southwest coast from 2015 to 2100, using sea level rise projections from the Intergovernmental Panel on Climate Change. Beach nourishment is shown to be a very effective adaptation strategy for sea level rise with shoreline change projections useful to estimate required rates of beach nourishment to counter sea level rise.
•Equation is proposed for shoreline change including effects of sea level rise.•Inputs include sand sources, sinks, and longshore transport gradients.•Estimates made of shoreline change based on sea level projections of the IPCC.•Beach nourishment is very effective adaptation strategy for sea level rise.
An improved measurement of the decay $B^0_S$ → $μ^+μ^-$ and searches for the decays $B^0$ → $μ^+μ^+$ and $B^0_S$ → $μ^+μ^-γ$ are performed at the LHCb experiment using data collected in proton-proton ...collisions at $\sqrt{s}$ = 7, 8 and 13 TeV. corresponding to integrated luminosities of 1, 2 and 6 fb-1, respectively. The $B^0_S$ → $μ^+μ^-$ branching fraction and effective lifetime are measured to be $\mathscr{B}$($B^0_S$ → $μ^+μ^-$) = (3.09$^{(+0.46+0.15)}_{(-0.43-0.11)}$) x 10-9 and $τ(B^0_s →μ^+μ^-)$ = (2.07 ± 0.29 ± 0.03) ps, respectively, where the uncertainties include both statistical and systematic contributions. No significant signal for $B^0$ → $μ^+μ^-$ and $B^0_S$ → $μ^+μ^-γ$ decays is found and the upper limits $\mathscr{B}$($B^0$ → $μ^+μ^-$) < 2.6 x 10-10 and $B^0_S$ → $μ^+μ^-γ$ < 2.0 x 10-9 at 95% confidence level are determined, where the latter is limited to the range $m_{μμ}$ > 4.9 GeV/c2. Additionally, the ratio between the $B^0$ → $μ^+μ^-$ and $B^0_S$ → $μ^+μ^-$ branching fractions is measured to be $\mathscr{R}_{μ+μ-}$ < 0.095 at 95% confidence level. The results are in agreement with the Standard Model predictions.
The Fennec climate programme aims to improve understanding of the Saharan climate system through a synergy of observations and modelling. We present a description of the Fennec airborne observations ...during 2011 and 2012 over the remote Sahara (Mauritania and Mali) and the advances in the understanding of mineral dust and boundary layer processes they have provided. Aircraft instrumentation aboard the UK FAAM BAe146 and French SAFIRE (Service des Avions Francais Instrumentes pour la Recherche en Environnement) Falcon 20 is described, with specific focus on instrumentation specially developed for and relevant to Saharan meteorology and dust. Flight locations, aims and associated meteorology are described. Examples and applications of aircraft measurements from the Fennec flights are presented, highlighting new scientific results delivered using a synergy of different instruments and aircraft. These include (1) the first airborne measurement of dust particles sizes of up to 300 microns and associated dust fluxes in the Saharan atmospheric boundary layer (SABL), (2) dust uplift from the breakdown of the nocturnal low-level jet before becoming visible in SEVIRI (Spinning Enhanced Visible Infra-Red Imager) satellite imagery, (3) vertical profiles of the unique vertical structure of turbulent fluxes in the SABL, (4) in situ observations of processes in SABL clouds showing dust acting as cloud condensation nuclei (CCN) and ice nuclei (IN) at -15 degree C, (5) dual-aircraft observations of the SABL dynamics, thermodynamics and composition in the Saharan heat low region (SHL), (6) airborne observations of a dust storm associated with a cold pool (haboob) issued from deep convection over the Atlas Mountains, (7) the first airborne chemical composition measurements of dust in the SHL region with differing composition, sources (determined using Lagrangian backward trajectory calculations) and absorption properties between 2011 and 2012, (8) coincident ozone and dust surface area measurements suggest coarser particles provide a route for ozone depletion, (9) discrepancies between airborne coarse-mode size distributions and AERONET (AERosol Robotic NETwork) sunphotometer retrievals under light dust loadings. These results provide insights into boundary layer and dust processes in the SHL region - a region of substantial global climatic importance.
A study of the lineshape of the χc1 ( 3872 ) state is made using a data sample corresponding to an integrated luminosity of 3 fb−1 collected in p p collisions at center-of-mass energies of 7 and ...8 TeV with the LHCb detector. Candidate χc1 ( 3872 ) and ψ ( 2S ) mesons from b -hadron decays are selected in the J / ψ π+ π− decay mode. Describing the lineshape with a Breit-Wigner function, the mass splitting between the χc1 ( 3872 ) and ψ ( 2S ) states, Δm, and the width of the χc1 ( 3872 ) state, ΓBW, are determined to be ..., where the first uncertainty is statistical and the second systematic. Using a Flatté-inspired model, the mode and full width at half maximum of the lineshape are determined to be ... . An investigation of the analytic structure of the Flatté amplitude reveals a pole structure, which is compatible with a quasibound D0 D*0 state but a quasivirtual state is still allowed at the level of 2 standard deviations. (ProQuest: ... denotes formulae omited.).
Purpose To evaluate whether decreased hamstring autograft size and decreased patient age are predictors of early graft revision. Methods Of 338 consecutive patients undergoing primary anterior ...cruciate ligament (ACL) reconstruction with hamstring autograft, 256 (75.7%) were evaluated. Graft size and patient age, gender, and body mass index at the time of ACL reconstruction were recorded, along with whether subsequent ACL revision was performed. Results The 256 patients comprised 136 male and 120 female patients and ranged in age from 11 to 52 years (mean, 25.0 years). The mean follow-up was 14 months (range, 6 to 47 months). Revision ACL reconstruction was performed in 18 of 256 patients (7.0%) at a mean of 12 months after surgery (range, 3 to 31 months). Revision was performed in 1 of 58 patients (1.7%) with grafts greater than 8 mm in diameter, 9 of 139 patients (6.5%) with 7.5- or 8-mm-diameter grafts, and 8 of 59 patients (13.6%) with grafts 7 mm or less in diameter ( P = .027). There was 1 revision performed in the 137 patients aged 20 years or older (0.7%), but 17 revisions were performed in the 119 patients aged under 20 years (14.3%) ( P < .0001). Most revisions (16 of 18) were noted to occur in patients aged under 20 years with grafts 8 mm in diameter or less, and the revision rate in this population was 16.4% (16 of 97 patients). Age less than 20 years at reconstruction (odds ratio OR, 18.97; 95% confidence interval CI, 2.43 to 147.06; P = .005), decreased graft size (OR, 2.20; 95% CI, 1.00 to 4.85; P = .05), and increased follow-up time (OR, 1.07; 95% CI, 1.02 to 1.12) were associated with increased risk of revision. Conclusions Decreased hamstring autograft size and decreased patient age are predictors of early graft revision. Use of hamstring autografts 8 mm in diameter or less in patients aged under 20 years is associated with higher revision rates. Level of Evidence Level III, retrospective comparative study.
Hyperglycemia is associated with increased mortality in critically ill patients. Randomized trials of intensive insulin therapy have reported inconsistent effects on mortality and increased rates of ...severe hypoglycemia. We conducted a meta-analysis to update the totality of evidence regarding the influence of intensive insulin therapy compared with conventional insulin therapy on mortality and severe hypoglycemia in the intensive care unit (ICU).
We conducted searches of electronic databases, abstracts from scientific conferences and bibliographies of relevant articles. We included published randomized controlled trials conducted in the ICU that directly compared intensive insulin therapy with conventional glucose management and that documented mortality. We included in our meta-analysis the data from the recent NICE-SUGAR (Normoglycemia in Intensive Care Evaluation - Survival Using Glucose Algorithm Regulation) study.
We included 26 trials involving a total of 13 567 patients in our meta-analysis. Among the 26 trials that reported mortality, the pooled relative risk (RR) of death with intensive insulin therapy compared with conventional therapy was 0.93 (95% confidence interval CI 0.83-1.04). Among the 14 trials that reported hypoglycemia, the pooled RR with intensive insulin therapy was 6.0 (95% CI 4.5-8.0). The ICU setting was a contributing factor, with patients in surgical ICUs appearing to benefit from intensive insulin therapy (RR 0.63, 95% CI 0.44-0.91); patients in the other ICU settings did not (medical ICU: RR 1.0, 95% CI 0.78-1.28; mixed ICU: RR 0.99, 95% CI 0.86-1.12). The different targets of intensive insulin therapy (glucose level < or = 6.1 mmol/L v. < or = 8.3 mmol/L) did not influence either mortality or risk of hypoglycemia.
Intensive insulin therapy significantly increased the risk of hypoglycemia and conferred no overall mortality benefit among critically ill patients. However, this therapy may be beneficial to patients admitted to a surgical ICU.
The design of minimum CRISPR RNA (crRNA) sets for detection of diverse RNA targets using sequence degeneracy has not been systematically addressed. We tested candidate degenerate Cas13a crRNA sets ...designed for detection of diverse RNA targets (Lassa virus). A decision tree machine learning (ML) algorithm (RuleFit) was applied to define the top attributes that determine the specificity of degenerate crRNAs to elicit collateral nuclease activity. Although the total number of mismatches (0-4) is important, the specificity depends as well on the spacing of mismatches, and their proximity to the 5' end of the spacer. We developed a predictive algorithm for design of candidate degenerate crRNA sets, allowing improved discrimination between "included" and "excluded" groups of related target sequences. A single degenerate crRNA set adhering to these rules detected representatives of all Lassa lineages. Our general ML approach may be applied to the design of degenerate crRNA sets for any CRISPR/Cas system.
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