2,729 research outputs found
Manifestation of the Hofstadter butterfly in far-infrared absorption
The far-infrared absorption of a two-dimensional electron gas with a
square-lattice modulation in a perpendicular constant magnetic field is
calculated self-consistently within the Hartree approximation. For strong
modulation and short period we obtain intra- and intersubband magnetoplasmon
modes reflecting the subbands of the Hofstadter butterfly in two or more Landau
bands. The character of the absorption and the correlation of the peaks to the
number of flux quanta through each unit cell of the periodic potential depends
strongly on the location of the chemical potential with respect to the
subbands, or what is the same, on the density of electrons in the system.Comment: RevTeX file + 4 postscript figures, to be published Phys. Rev. B
Rapid Com
SecureKeeper: confidential zooKeeper using intel SGX
Cloud computing, while ubiquitous, still suffers from trust issues, especially for applications managing sensitive data. Third-party coordination services such as ZooKeeper and Consul are fundamental building blocks for cloud applications, but are exposed to potentially sensitive application data. Recently, hardware trust mechanisms such as Intel's Software Guard Extensions (SGX) offer trusted execution environments to shield application data from untrusted software, including the privileged Operating System (OS) and hypervisors. Such hardware support suggests new options for securing third-party coordination services. We describe SecureKeeper, an enhanced version of the ZooKeeper coordination service that uses SGX to preserve the confidentiality and basic integrity of ZooKeeper-managed data. SecureKeeper uses multiple small enclaves to ensure that (i) user-provided data in ZooKeeper is always kept encrypted while not residing inside an enclave, and (ii) essential processing steps that demand plaintext access can still be performed securely. SecureKeeper limits the required changes to the ZooKeeper code base and relies on Java's native code support for accessing enclaves. With an overhead of 11%, the performance of SecureKeeper with SGX is comparable to ZooKeeper with secure communication, while providing much stronger security guarantees with a minimal trusted code base of a few thousand lines of code
Is diversity good?
Prominent ethical and policy issues such as affirmative action and female
enrollment in science and engineering revolve around the idea that diversity is
good. However, even though diversity is an ambiguous concept, a precise
definition is seldom provided. We show that diversity may be construed as a
factual description, a craving for symmetry, an intrinsic good, an instrumental
good, a symptom, or a side effect. These acceptions differ vastly in their
nature and properties. The first one cannot lead to any action and the second
one is mistaken. Diversity as intrinsic good is a mere opinion, which cannot be
concretely applied; moreover, the most commonly invoked forms of diversity
(sexual and racial) are not intrinsically good. On the other hand, diversity as
instrumental good can be evaluated empirically and can give rise to policies,
but these may be very weak. Finally, symptoms and side effects are not actually
about diversity. We consider the example of female enrollment in science and
engineering, interpreting the various arguments found in the literature in
light of this polysemy.
Keywords: ethics, policy, higher education, female students, minority
students, affirmative actionComment: 7 page
A genome-wide association study on hematopoietic stem cell transplantation reveals novel genomic loci associated with transplant outcomes
Copyright \ua9 2024 Rosenberger, Crossland, Dressel, Kube, Wolff, Wulf, Bickeb\uf6ller, Dickinson and Holler.Introduction: Data on genomic susceptibility for adverse outcomes after hematopoietic stem cell transplantation (HSCT) for recipients are scarce. Methods: We performed a genome wide association study (GWAS) to identify genes associated with survival/mortality, relapse, and severe graft-versus-host disease (sGvHD), fitting proportional hazard and subdistributional models to data of n=1,392 recipients of European ancestry from three centres. Results: The single nucleotide polymorphism (SNP) rs17154454, intronic to the neuronal growth guidant semaphorin 3C gene (SEMA3C), was genome-wide significantly associated with event-free survival (p=7.0x10-8) and sGvHD (p=7.5x10-8). Further associations were detected for SNPs in the Paxillin gene (PXN) with death without prior relapse or sGvHD, as well as for SNPs of the Plasmacytoma Variant Translocation 1 gene (PVT1, a long non-coding RNA gene), the Melanocortin 5 Receptor (MC5R) gene and the WW Domain Containing Oxidoreductase gene (WWOX), all associated with the occurrence of sGvHD. Functional considerations support the observed associations. Discussion: Thus, new genes were identified, potentially influencing the outcome of HSCT
The Physiotherapy eSkills Training Online resource improves performance of practical skills: A controlled trial
Background: E-learning is a common and popular mode of educational delivery, but little is known about its effectiveness in teaching practical skills. The aim of this study was to determine whether the Physiotherapy eSkills Training Online resource in addition to usual teaching improved the performance of practical skills in physiotherapy students. Method: This study was a non-randomised controlled trial. The participants were graduate entry physiotherapy students enrolled in consecutive semesters of a neurological physiotherapy unit of study. The experimental group received the Physiotherapy eSkills Training Online resource as well as usual teaching. The Physiotherapy eSkills Training Online resource is an online resource incorporating (i) video-clips of patient-therapist simulations; (ii) supportive text describing the aim, rationale, equipment, key points, common errors and methods of progression; and (iii) a downloadable PDF document incorporating the online text information and a still image of the video-clip for each practical skill. The control group received usual teaching only. The primary outcomes were the overall performance of practical skills as well as their individual components, measured using a practical examination. Results: The implementation of the Physiotherapy eSkills Training Online resource resulted in an increase of 1.6 out of 25 (95% CI -0.1 to 3.3) in the experimental group compared with the control group. In addition, the experimental group scored 0.5 points out of 4 (95% CI 0 to 1.1) higher than the control group for 'effectiveness of the practical skill' and 0.6 points out of 4 (95% CI 0.1 to 1.1) higher for 'rationale for the practical skill'. Conclusion: There was improvement in performance of practical skills in students who had access to the Physiotherapy eSkills Training Online resource in addition to usual teaching. Students considered the resource to be very useful for learning.7 page(s
The late MIS 5 Mediterranean tephra markers: A reappraisal from peninsular Italy terrestrial records
We present new tephrostratigraphic records from the late MIS 5 (ca 110e80 ka) terrestrial sediments
from southern and central Italy. On the one hand, the central Italy record consists of an outcropping
lacustrine sequence from the Sulmona intermountain basin that contains four trachyticephonolitic
tephra layers (POP3, POP2a, POP2b, POP1), all of which show a K-alkaline affinity that is typical for
the Roman co-magmatic Province. The POP3 and POP1 layers were dated by 40Ar/39Ar method at
106.2 1.3 ka (2s) and 92.4 4.6 ka (2s), respectively. The sequence in southern Italy, on the other
hand, is represented by post-Tyrrhenian coastal deposits of the Cilento area, Campania, which contain
two trachytic layers (CIL2, CIL1) that show the same K-alkaline affinity. Based on their chemical
compositions and radiometric ages, POP3 and POP1 are firmly correlated with the marine tephra layers
X-5 (105 2 ka) and C-22 (ca 90 ka), which, in turn, match tephras TM-25 and TM-23-11, respectively,
in the lacustrine sequence of Lago Grande di Monticchio (southern Italy). Of note, the POP1 layer also
matches the Adriatic Sea tephra PRAD 2517 that was previously correlated with the older X-5 layer. The
tephra couplet POP2a and POP2b (ca 103 and 103.5 ka, extrapolated ages) are compatible with the TM-
24b and TM-24-3 tephras in Monticchio, which match both the stratigraphic positions and the chemical
compositions. In the Cilento area, as well as the already described X-6 layer (ca 108 ka) (CIL2), we
recognise a new stratigraphic superimposed layer (CIL1) that matches the POP3/TM-25/C-27/X-5
Mediterranean marker(s). In summary, the data presented here provide new chemical and 40Ar/39Ar
chronological constraints towards a robust late MIS 5 tephrostratigraphy of the central Mediterranean,
although at the same time, they also reveal how the tephrostratigraphy itself might be flawed when
dealing with tephra markers that are not adequately constrained and characterised.Published31-451V. Storia eruttivaJCR Journa
Technological Devices in the Archives: A Policy Analysis
Doing research in the archive is the cornerstone of humanities scholarship.
Various archives institute policies regarding the use of technological
devices, such as mobile phones, laptops, and cameras in their reading rooms.
Such policies directly affect the scholars as the devices mediate the nature of
their interaction with the source materials in terms of capturing, organizing,
note taking, and record keeping for future use of found materials. In this paper,
we present our analysis of the policies of thirty archives regarding the use of
technology in their reading rooms. This policy analysis, along with data from
interviews of scholars and archivists, is intended to serve as a basis for developing
mobile applications for assisting scholars in their research activities. In this
paper we introduce an early prototype of such a mobile application—
AMTracker.Informatio
Mightyl: A compositional translation from mitl to timed automata
Metric Interval Temporal Logic (MITL) was first proposed in the early 1990s as a specification formalism for real-time systems. Apart from its appealing intuitive syntax, there are also theoretical evidences that make MITL a prime real-time counterpart of Linear Temporal Logic (LTL). Unfortunately, the tool support for MITL verification is still lacking to this day. In this paper, we propose a new construction from MITL to timed automata via very-weak one-clock alternating timed automata. Our construction subsumes the well-known construction from LTL to Büchi automata by Gastin and Oddoux and yet has the additional benefits of being compositional and integrating easily with existing tools. We implement the construction in our new tool MightyL and report on experiments using Uppaal and LTSmin as back-ends
Quasillitid and Alanellid Ostracods from the Centerfield Limestone of Western New York
15-31http://deepblue.lib.umich.edu/bitstream/2027.42/48330/2/ID171.pd
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