926 research outputs found
Universal recovery maps and approximate sufficiency of quantum relative entropy
The data processing inequality states that the quantum relative entropy
between two states and can never increase by applying the same
quantum channel to both states. This inequality can be
strengthened with a remainder term in the form of a distance between and
the closest recovered state , where
is a recovery map with the property that . We show the existence of an explicit recovery map
that is universal in the sense that it depends only on and the quantum
channel to be reversed. This result gives an alternate,
information-theoretic characterization of the conditions for approximate
quantum error correction.Comment: v3: 24 pages, 1 figure, final version published in Annales Henri
Poincar\'
Achieving the Capacity of any DMC using only Polar Codes
We construct a channel coding scheme to achieve the capacity of any discrete
memoryless channel based solely on the techniques of polar coding. In
particular, we show how source polarization and randomness extraction via
polarization can be employed to "shape" uniformly-distributed i.i.d. random
variables into approximate i.i.d. random variables distributed ac- cording to
the capacity-achieving distribution. We then combine this shaper with a variant
of polar channel coding, constructed by the duality with source coding, to
achieve the channel capacity. Our scheme inherits the low complexity encoder
and decoder of polar coding. It differs conceptually from Gallager's method for
achieving capacity, and we discuss the advantages and disadvantages of the two
schemes. An application to the AWGN channel is discussed.Comment: 9 pages, 7 figure
Sequential Strong Measurements and Heat Vision
We study scenarios where a finite set of non-demolition von-Neumann
measurements are available. We note that, in some situations, repeated
application of such measurements allows estimating an infinite number of
parameters of the initial quantum state, and illustrate the point with a
physical example. We then move on to study how the system under observation is
perturbed after several rounds of projective measurements. While in the finite
dimensional case the effect of this perturbation always saturates, there are
some instances of infinite dimensional systems where such a perturbation is
accumulative, and the act of retrieving information about the system increases
its energy indefinitely (i.e., we have `Heat Vision'). We analyze this effect
and discuss a specific physical system with two dichotomic von-Neumann
measurements where Heat Vision is expected to show.Comment: See the Appendix for weird examples of heat visio
Universal recoverability in quantum information
The quantum relative entropy is well known to obey a monotonicity property (i.e., it does not increase under the action of a quantum channel). Here we present several refinements of this entropy inequality, some of which have a physical interpretation in terms of recovery from the action of the channel. The recovery channel given here is explicit and universal, depending only on the channel and one of the arguments to the relative entropy
Andreev reflections in the pseudogap state of cuprate supercondcutors
We propose that, if the pseudogap state in the cuprate superconductors can be
described in terms of the phase-incoherent preformed pairs, there should exist
Andreev reflection from these pairs even above the superconducting transition
temperature, . After giving qualitative arguments for this effect, we
present more quantitative calculations based on the Bogoliubov--de Gennes
equation. Experimental observations of the effects of Andreev reflections above
---such as an enhanced tunneling conductance below the gap along the
copper oxide plane---could provide unambiguous evidence for the preformed pairs
in the pseudogap state.Comment: 5 pages, 1 figur
Emisari: a management information system designed to aid and involve people
The EMISARI System described in this paper represents a major departure from conventional MIS design. It is oriented not toward data per se, but rather toward activities of the people who generate and use the data. Thus it provides not merely for reporting up the chain of command, but also for dissemination of policy guidance and reference material down the chain, and for lateral communication among all users. It places a premium upon flexibility, to permit rapid system modifications in response to changes in user functions and needs and it offers a greatly simplified operation, to avoid any necessity for extensive user training or complex operation manuals. The overall approach may be viewed as a greatly modernized version of the classic telephone party line, using a computer to organize, selectively sort, and store-and-forward a constant flow of statistics, messages, estimates, reference materials, guidelines, notices, and other informational accountrements of a modern management operation
Taxonomic revision of true morels (Morchella) in Canada and the United States
Recent molecular phylogenetic studies have revealed the existence of at least 50 species of Morchella worldwide and demonstrated a high degree of continental endemism within the genus. Here we describe 19 phylogenetic species of Morchella from North America, 14 of which are new (M. diminutiva, M. virginiana, M. esculentoides, M. prava, M. cryptica, M. frustrata, M. populiphila, M. sextelata, M. septimelata, M. capitata, M. importuna, M. snyderi, M. brunnea and M. septentrionalis). Existing species names (M. rufobrunnea, M. tomentosa, M. punctipes and M. angusticeps) are applied to four phylogenetic species, and formal description of one species (M. sp. Mel-8 ) is deferred pending study of additional material. Methods for assessing morphological features in Morchella are delineated, and a key to the known phylogenetic species of Morchella in North America is provided. Type studies of M. crassistipa, M. hotsonii, M. angusticeps and M. punctipes are provided. Morchella crassistipa is designated nomen dubium
Taxonomic revision of true morels (Morchella) in Canada and the United States
Recent molecular phylogenetic studies have revealed the existence of at least 50 species of Morchella worldwide and demonstrated a high degree of continental endemism within the genus. Here we describe 19 phylogenetic species of Morchella from North America, 14 of which are new (M. diminutiva, M. virginiana, M. esculentoides, M. prava, M. cryptica, M. frustrata, M. populiphila, M. sextelata, M. septimelata, M. capitata, M. importuna, M. snyderi, M. brunnea and M. septentrionalis). Existing species names (M. rufobrunnea, M. tomentosa, M. punctipes and M. angusticeps) are applied to four phylogenetic species, and formal description of one species (M. sp. Mel-8 ) is deferred pending study of additional material. Methods for assessing morphological features in Morchella are delineated, and a key to the known phylogenetic species of Morchella in North America is provided. Type studies of M. crassistipa, M. hotsonii, M. angusticeps and M. punctipes are provided. Morchella crassistipa is designated nomen dubium
Psychological Burden in Female, Iraqi Refugees Who Suffered Extreme Violence by the âIslamic Stateâ: The Perspective of Care Providers
Introduction: A large number of refugees suffer from mental disorders such as post-traumatic stress disorder (PTSD). In the context of a special quota project, 1100 Yazidi women from Northern Iraq who had suffered extreme violence by the so-called Islamic State (IS) were brought to Germany to receive specialized treatment. This study aims to investigate the psychological burden and trauma-related symptoms of these female IS-victims from the perspectives of their care providers.Material and methods: Care providers with various professional backgrounds (N = 96) were asked to complete a self-developed questionnaire on a Likert-type scale ranging from 1 (very low) to 7 (very high) analyzing the psychological burden and trauma-related symptoms of the IS-traumatized women since their arrival in Germany. We controlled for potential confounders, namely the care providers' personal experiences of trauma and flight, by using chi-square tests.Results: The mean psychological burden for the whole period in Germany as perceived by care providers was M = 5.51 (SD = 0.94). As the main factors of distress the care providers reported: worries about family members in Iraq (M = 6.69; SD = 0.69), worries about relatives' possibilities to be granted asylum in Germany (M = 6.62; SD = 0.68), and uncertainties regarding their future (M = 5.89; SD = 1.02). The most prominent trauma-related psychological symptoms were nightmares (M = 6.43; SD = 0.54). The care providers reported that somatic complaints have been present among the refugees in the following manifestation: pain (M = 6.24; SD = 1.08), gastrointestinal complaints (M = 4.62; SD = 1.62), and dizziness (M = 4.40; SD = 1.59). The care providers' personal experiences of trauma and flight had no significant influence on their response behavior.Discussion: Care providers working with IS-traumatized female refugees evaluate the psychological burden and trauma-related somatic and psychological symptom loads of their clients as very high. The results of this study provide important information about the perceptions of care providers working in a refugee-services context and may provide insights for the progression of specialized treatment programs and interventions for highly traumatized refugees and culture-sensitive training programs for their care providers
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