422 research outputs found
Quasiparticle relaxation dynamics in cuprates and lifetimes of low-energy states: Femtosecond data from underdoped to overdoped YBCO and mercury compounds
We show that low-energy spectral features in the cuprates can be separated
into different components by the measurement of the recombination dynamics of
different low-energy excitations in real-time using femtosecond laser
spectroscopy. Quasiparticle (QP) recombination across the gap and intra-gap
localized state relaxation processes exhibit qualitatively different time- and
temperature-dependences. The relaxation measurements also show the existence of
two distinct coexisting energy gaps near optimum doping and in the overdoped
region, one more or less temperature independent (which exists above and below
Tc) and one which closes at Tc in a mean-field like fashion. Thus systematic
studies of QP recombination as a function of doping and temperature suggest
that the ground state of the cuprates is a mixed Boson-Fermion system with
localised states present over the entire region of the phase diagram.Comment: 4 pages, acepted for publication in Physica C, invited paper given at
M2S, Feb. 20 - 25, 2000, Houston, US
Policymakers’ horizon and trade reforms: the protectionist effect of elections
This paper shows that electoral incentives deter politicians from supporting trade liber- alization. We focus on all major trade liberalization bills introduced since the early 1970s in the U.S. Congress, in which House and Senate members serve respectively two- and six-year terms and one third of senators face elections every two years. We show that senators are more likely to support trade liberalization than House representatives. How- ever, this result does not hold for the last generation of senators, who face elections at the same time as House members, suggesting that inter-cameral differences are driven by term length. Considering senators alone, we find that the last generation is less likely to support trade liberalization than the previous two. This result is pervasive and holds both when comparing the behavior of different senators voting on the same bill and that of individual senators voting on different bills. The protectionist effect of election proximity disappears for senators who are retiring or hold safe seats
Pharmacological prevention of postictal agitation after electroconvulsive therapy—A systematic review and meta-analysis
BackgroundPostictal agitation (PIA) after electroconvulsive therapy (ECT) is a serious clinical problem estimated to occur in 7–36% of patients and recur in 19–54% of patients. PIA has the potential to cause dangerous situations for the patient and staff members aside from the financial impact. To date, it is unclear which pharmacological interventions should be used in the management of PIA. This study aimed to systematically review the (preventative) pharmacological treatment options for PIA after ECT.MethodA systematic search was done in PubMed, EMBASE, PsycINFO, and Web of Science from inception until 10 November 2022. We included randomized trials with any pharmacological intervention or comparison and a predefined outcome measure on PIA. Studies that solely included patients with neurodegenerative disorders or stroke were excluded. Data quality was assessed with the RoB2 and GRADE. Meta-analysis was performed if possible. This study was registered on PROSPERO under CRD42021262323.ResultsWe screened 2,204 articles and included 14 studies. Dexmedetomidine was investigated in 10 studies. Alfentanil, lignocaine, esmolol, midazolam, propofol, ketamine, haloperidol, and diazepam were each studied in only one study. Meta-analysis revealed an OR of 0.45 (0.32–0.63), a moderate effect size, in favor of dexmedetomidine than placebo to prevent PIA with very low heterogeneity (I2 = 0%). The certainty of the evidence was moderate. The other interventions studied were all found to have low certainty of evidence.ConclusionFor clinical practice, we believe that our results indicate that dexmedetomidine should be considered for the prevention of PIA in patients that have previously experienced PIA
Comprehensive genome-wide association study of different forms of hernia identifies more than 80 associated loci
Hernias are characterized by protrusion of an organ or tissue through its surrounding cavity and often require surgical repair. In this study we identify 65,492 cases for five hernia types in the UK Biobank and perform genome-wide association study scans for these five types and two combined groups. Our results show associated variants in all scans. Inguinal hernia has the most associations and we conduct a follow-up study with 23,803 additional cases from four study groups giving 84 independently associated variants. Identified variants from all scans are collapsed into 81 independent loci. Further testing shows that 26 loci are associated with more than one hernia type, suggesting substantial overlap between the underlying genetic mechanisms. Pathway analyses identify several genes with a strong link to collagen and/or elastin (ADAMTS6, ADAMTS16, ADAMTSL3, LOX, ELN) in the vicinity of associated loci for inguinal hernia, which substantiates an essential role of connective tissue morphology. Hernias involve protrusion of an organ or tissue through its surrounding cavity. Here the authors carry out GWAS for five types of hernia and find 81 variants, most of which are associated with inguinal hernia; downstream analysis suggests an important role for connective tissue morphology.Peer reviewe
Spin relaxation in (110) and (001) InAs/GaSb superlattices
We report an enhancement of the electron spin relaxation time (T1) in a (110)
InAs/GaSb superlattice by more than an order of magnitude (25 times) relative
to the corresponding (001) structure. The spin dynamics were measured using
polarization sensitive pump probe techniques and a mid-infrared, subpicosecond
PPLN OPO. Longer T1 times in (110) superlattices are attributed to the
suppression of the native interface asymmetry and bulk inversion asymmetry
contributions to the precessional D'yakonov Perel spin relaxation process.
Calculations using a nonperturbative 14-band nanostructure model give good
agreement with experiment and indicate that possible structural inversion
asymmetry contributions to T1 associated with compositional mixing at the
superlattice interfaces may limit the observed spin lifetime in (110)
superlattices. Our findings have implications for potential spintronics
applications using InAs/GaSb heterostructures.Comment: 4 pages, 2 figure
Photo-physics and electronic structure of lateral graphene/MoS2 and metal/MoS2 junctions
Integration of semiconducting transition metal dichalcogenides (TMDs) into
functional optoelectronic circuitries requires an understanding of the charge
transfer across the interface between the TMD and the contacting material.
Here, we use spatially resolved photocurrent microscopy to demonstrate
electronic uniformity at the epitaxial graphene/molybdenum disulfide (EG/MoS2)
interface. A 10x larger photocurrent is extracted at the EG/MoS2 interface when
compared to metal (Ti/Au) /MoS2 interface. This is supported by semi-local
density-functional theory (DFT), which predicts the Schottky barrier at the
EG/MoS2 interface to be ~2x lower than Ti/MoS2. We provide a direct
visualization of a 2D material Schottky barrier through combination of angle
resolved photoemission spectroscopy with spatial resolution selected to be ~300
nm (nano-ARPES) and DFT calculations. A bending of ~500 meV over a length scale
of ~2-3 micrometer in the valence band maximum of MoS2 is observed via
nano-ARPES. We explicate a correlation between experimental demonstration and
theoretical predictions of barriers at graphene/TMD interfaces. Spatially
resolved photocurrent mapping allows for directly visualizing the uniformity of
built-in electric fields at heterostructure interfaces, providing a guide for
microscopic engineering of charge transport across heterointerfaces. This
simple probe-based technique also speaks directly to the 2D synthesis community
to elucidate electronic uniformity at domain boundaries alongside morphological
uniformity over large areas
Is Inequality Growing as American Workers Fall Behind?
A popular and highly politicized theme today is that US workers are falling behind as their real wages fall and income gets redistributed to the rich. This article looks at some reasons that income inequality could rise, and then explores whether, in fact, workers are losing out. It looks at the suggestion that workers are falling behind relative to the wealthy, and at evidence on whether workers real wages have been falling, or perhaps only manufacturing wages. It also examines whether there is a growing “wealth gap” and whether it is due to falling labor compensation relative to wealth. Finally it examines the hypothesis that relatively inexperienced or unskilled workers are falling behind by fixing a skill level and seeing how real wages are changing over the recent past. The evidence here provides a perspective on why some analysts might believe that there is rising inequality or an emerging wealth gap, or that workers are falling behind, but generally it is not favorable to these pessimistic views of how well workers are doing. While inequality may have risen in recent decades, and there are strong reasons to think that the evidence for this is weak, there is also a strong reason to think that it would be a normal function of an aging population and nothing more. Short of population control or unexplainable and unfair redistribution from the old to the young, there may be nothing that can or should be done to reverse the rise in inequality. Finally the paper argues that there is a wealth gap, but it is due to falling real interest rates and a decline and not due to declining compensation, either absolutely or relative to overall income
Assignment reversals : trade, skill allocation and wage inequality
The allocation of skilled labor across industries shapes inter-industry wage differences and wage inequality. This paper shows the ranking of industries by workforce skill differs between developed and developing countries and develops a multi-sector assignment model to understand the causes and consequences of this fact. Heterogeneous agents leverage their ability through their span of control over an homogeneous input. In equilibrium, higher skill agents sort into sectors where the cost per efficiency unit of input is lower. Consequently, skill allocation is endogenous to country-sector specific variation in input productivity and costs and when the ranking of sectors by effective input costs differs across countries there is an assignment reversal. Assignment reversals between North and South have novel implications for how trade affects wages because they imply the Stolper-Samuelson theorem does not hold. Instead, each country has a comparative advantage in its high skill sector and output trade integration causes the relative wage of high skill workers, and wage inequality within the high skill sector, to increase in both countrie
Comparison of Tobacco Control Scenarios: Quantifying Estimates of Long-Term Health Impact Using the DYNAMO-HIA Modeling Tool
There are several types of tobacco control interventions/policies which can change future smoking exposure. The most basic intervention types are 1) smoking cessation interventions 2) preventing smoking initiation and 3) implementation of a nationwide policy affecting quitters and starters simultaneously. The possibility for dynamic quantification of such different interventions is key for comparing the timing and size of their effects
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