336 research outputs found
Towards a Graphene-Based Quantum Impedance Standard
Precision measurements of the quantum Hall resistance with alternating
current (ac) in the kHz range were performed on epitaxial graphene in order to
assess its suitability as a quantum standard of impedance. The quantum Hall
plateaus measured with alternating current were found to be flat within one
part in 10^7. This is much better than for plain GaAs quantum Hall devices and
shows that the magnetic-flux-dependent capacitive ac losses of the graphene
device are less critical. The observed frequency dependence of about
-8x10^-8/kHz is comparable in absolute value to the positive frequency
dependence of plain GaAs devices, but the negative sign is attributed to stray
capacitances which we believe can be minimized by a careful design of the
graphene device. Further improvements thus may lead to a simpler and more
user-friendly quantum standard for both resistance and impedance
The Impact of Sleep on Female Sexual Response and Behavior: A Pilot Study
IntroductionThe etiological role of sleep disturbance in sexual difficulties has been largely overlooked. Research suggests that short sleep duration and poor sleep quality lead to poor female sexual response. However, prior research consists of cross‐sectional studies, and the influence of sleep on sexual functioning and behavior has not been prospectively examined.AimWe sought to examine the influence of nightly sleep duration, sleep quality, and sleep onset latency on daily female sexual response and activity.MethodsThis study used a longitudinal design to study 171 women free of antidepressants and with reliable Internet access who were recruited from a university setting in the United States. Participants first completed baseline measures in a laboratory, and then completed web‐delivered surveys at their habitual wake time for 14 consecutive days.Main Outcome MeasuresAll outcome measures were modified for daily recall. Participants completed the Profile of Female Sexual Function's desire, subjective arousal, and orgasmic functioning scales and the Female Sexual Function Index's genital arousal scale, and indicated whether they engaged in partnered sexual activity or self‐stimulation in response to dichotomous items.ResultsAnalyses revealed that longer sleep duration was related to greater next‐day sexual desire (b = 0.32, P = 0.02), and that a 1‐hour increase in sleep length corresponded to a 14% increase in odds of engaging in partnered sexual activity (odds ratio = 1.14, P < 0.05). In contrast, sleeping longer predicted poorer next‐day genital arousal (b = −0.19, P < 0.01). However, results showed that women with longer average sleep duration reported better genital arousal than women with shorter average sleep length (b = 0.54, P = 0.03).ConclusionsObtaining sufficient sleep is important to the promotion of healthy sexual desire and genital response, as well as the likelihood of engaging in partnered sexual activity. These relationships were independent of daytime affect and fatigue. Future directions may investigate sleep disorders as risk factors for sexual dysfunction. Kalmbach DA, Arnedt JT, Pillai V, and Ciesla JA. The impact of sleep on female sexual response and behavior: A pilot study. J Sex Med 2015;12:1221–1232.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111751/1/jsm12858.pd
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A Rare Oncologic Emergency: Spontaneous Tumor Lysis Syndrome in Metastatic Colon Adenocarcinoma
Tumor lysis syndrome is an oncologic emergency that can present with variable symptoms and is truly a laboratory-based diagnosis without pathognomonic clinical findings. The classical teaching is to consider this diagnosis in cancer patients undergoing chemotherapy. We present the case of a 66-year-old female with newly diagnosed metastatic liver adenocarcinoma, not on chemotherapy, who was diagnosed with spontaneous tumor lysis syndrome. Cognizance of this syndrome and associated laboratory findings are paramount to diagnosis and rapid intervention
Many worlds and modality in the interpretation of quantum mechanics: an algebraic approach
Many worlds interpretations (MWI) of quantum mechanics avoid the measurement
problem by considering every term in the quantum superposition as actual. A
seemingly opposed solution is proposed by modal interpretations (MI) which
state that quantum mechanics does not provide an account of what `actually is
the case', but rather deals with what `might be the case', i.e. with
possibilities. In this paper we provide an algebraic framework which allows us
to analyze in depth the modal aspects of MWI. Within our general formal scheme
we also provide a formal comparison between MWI and MI, in particular, we
provide a formal understanding of why --even though both interpretations share
the same formal structure-- MI fall pray of Kochen-Specker (KS) type
contradictions while MWI escape them.Comment: submitted to the Journal of Mathematical Physic
Type-Decomposition of a Pseudo-Effect Algebra
The theory of direct decomposition of a centrally orthocomplete effect
algebra into direct summands of various types utilizes the notion of a
type-determining (TD) set. A pseudo-effect algebra (PEA) is a (possibly)
noncommutative version of an effect algebra. In this article we develop the
basic theory of centrally orthocomplete PEAs, generalize the notion of a TD set
to PEAs, and show that TD sets induce decompositions of centrally orthocomplete
PEAs into direct summands.Comment: 18 page
Information-theoretic principle entails orthomodularity of a lattice
Quantum logical axiomatic systems for quantum theory usually include a
postulate that a lattice under consideration is orthomodular. We propose a
derivation of orthomodularity from an information-theoretic axiom. This
provides conceptual clarity and removes a long-standing puzzle about the
meaning of orthomodularity.Comment: Version prior to published, with slight modification
A topos for algebraic quantum theory
The aim of this paper is to relate algebraic quantum mechanics to topos
theory, so as to construct new foundations for quantum logic and quantum
spaces. Motivated by Bohr's idea that the empirical content of quantum physics
is accessible only through classical physics, we show how a C*-algebra of
observables A induces a topos T(A) in which the amalgamation of all of its
commutative subalgebras comprises a single commutative C*-algebra. According to
the constructive Gelfand duality theorem of Banaschewski and Mulvey, the latter
has an internal spectrum S(A) in T(A), which in our approach plays the role of
a quantum phase space of the system. Thus we associate a locale (which is the
topos-theoretical notion of a space and which intrinsically carries the
intuitionistic logical structure of a Heyting algebra) to a C*-algebra (which
is the noncommutative notion of a space). In this setting, states on A become
probability measures (more precisely, valuations) on S(A), and self-adjoint
elements of A define continuous functions (more precisely, locale maps) from
S(A) to Scott's interval domain. Noting that open subsets of S(A) correspond to
propositions about the system, the pairing map that assigns a (generalized)
truth value to a state and a proposition assumes an extremely simple
categorical form. Formulated in this way, the quantum theory defined by A is
essentially turned into a classical theory, internal to the topos T(A).Comment: 52 pages, final version, to appear in Communications in Mathematical
Physic
Kochen-Specker Sets and Generalized Orthoarguesian Equations
Every set (finite or infinite) of quantum vectors (states) satisfies
generalized orthoarguesian equations (OA). We consider two 3-dim
Kochen-Specker (KS) sets of vectors and show how each of them should be
represented by means of a Hasse diagram---a lattice, an algebra of subspaces of
a Hilbert space--that contains rays and planes determined by the vectors so as
to satisfy OA. That also shows why they cannot be represented by a special
kind of Hasse diagram called a Greechie diagram, as has been erroneously done
in the literature. One of the KS sets (Peres') is an example of a lattice in
which 6OA pass and 7OA fails, and that closes an open question of whether the
7oa class of lattices properly contains the 6oa class. This result is important
because it provides additional evidence that our previously given proof of noa
=< (n+1)oa can be extended to proper inclusion noa < (n+1)oa and that nOA form
an infinite sequence of successively stronger equations.Comment: 16 pages and 5 figure
Quantum probabilities as Dempster-Shafer probabilities in the lattice of subspaces.
yesThe orthocomplemented modular lattice of subspaces L[H(d)] , of a quantum system with d-dimensional Hilbert space H(d), is considered. A generalized additivity relation which holds for Kolmogorov probabilities is violated by quantum probabilities in the full lattice L[H(d)] (it is only valid within the Boolean subalgebras of L[H(d)] ). This suggests the use of more general (than Kolmogorov) probability theories, and here the Dempster-Shafer probability theory is adopted. An operator D(H1,H2) , which quantifies deviations from Kolmogorov probability theory is introduced, and it is shown to be intimately related to the commutator of the projectors P(H1),P(H2) , to the subspaces H 1, H 2. As an application, it is shown that the proof of the inequalities of Clauser, Horne, Shimony, and Holt for a system of two spin 1/2 particles is valid for Kolmogorov probabilities, but it is not valid for Dempster-Shafer probabilities. The violation of these inequalities in experiments supports the interpretation of quantum probabilities as Dempster-Shafer probabilities
A New Reconstruction for Permian East Gondwana Based on Zircon Data From Ophiolite of the East Australian Great Serpentinite Belt
The Great Serpentinite Belt of eastern Australia is a similar to 1500 km long dismembered ophiolite assumed to be Cambrian based on studies of small (typically <50 m(2)) exotic meta-igneous inclusions despite contrasting ages (Cambrian-Devonian) and complex P-T histories. To overcome these issues, we studied a similar to 18 km(2) coherent block of dismembered ophiolite that provides robust geological context to sampling the ophiolite. Zircon U-Pb-Hf-O isotope and trace analyses from three plagiogranite dykes cutting massive gabbro confirm similar to 283-277 Ma ages and a mantle source. As a result, we argue older Cambrian to Devonian plagiogranite and subducted blocks were inherited from previous subduction events in eastern Australia. These findings allow us to match the Great Serpentinite Belt with the contemporary Dun Mountain ophiolite (New Zealand) and the Koh ophiolite (New Caledonia), thus supporting a new, integrated Pacific Gondwana margin paleogeography involving multiple arcs and subduction zones.
Plain Language Summary Ophiolites are fragments of oceanic crust and mantle that have been thrusted onto continents by tectonics. Ophiolites provide important records of oceanic lithosphere and for assessing the timing of significant tectonic events. Previous studies of the Great Serpentinite Belt of eastern Australia, established a similar to 530 Myr age. However, studies focused on small (typically < 50 m(2)) exotic fault bounded blocks of ophiolitic material of varying geological ages and complex metamorphic histories. By focusing on an intact 18 km(2) fragment of oceanic crust with reliable geological relationships and low degrees of metamorphism, our results show this ophiolite is far younger (similar to 280 Myr old). This age overlaps with ophiolites in New Caledonia and New Zealand on what was the paleo-Pacific Gondwana margin. This new discovery leads to a new paleogeography for this period and improves geological links between eastern Australia, New Zealand, and New Caledonia.Funding was provided by UNE IRG funds to Milan and Australian Research Council Grants (Belousova, FT110100685). J. Kalmbach was sup-ported by the DAAD Rise Worldwide progra
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