329 research outputs found

    The Biomineralization in Social Wasps (Vespinae): The Presence of Statoliths

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    In social wasps granular aggregates occur mainly in the head region and the body integument. In the former location they are present both on the outer and inner side of the frons. On the outer side of the frons, in a groove traversing its center, there is a deep pit surrounded by a membrane which forms a cyst-like sac. In the pit of the hornet Vespa orientalis (Linne, 1771), there are aggregates comprising silicon (Sl), potassium (K), calcium (Ca) and iron (Fe), which are arranged in morula-like fashion. A granular material is secreted at the base of sensory hairs (sensilla), distributed on both sides of the groove, as well as along their shafts. Aggregates of sillcon and calcium are also present on the inner side of the frons. The integumental aggregates are comprised of yellow pigment granules. In the abdominal region these granules, which are concentrated in yellow stripes, assume a quasi-cylindrical shape, measuring 0.6-0.8 ÎĽmin length and 0.3-0.4 ÎĽmin diameter. Their structure is affected by caste, age, exposure to sunlight, and drugs introduced through feeding. Feeding on colchicine induces degeneration of the granules, whereas feeding on xanthines renders them refractory to the destructive action of colchicine. Their main metallic element is K. We postulate that 1) the granules on both sides of the frons are part of a tympanic and static organ; 2) the yellow granules (YG) dispersed all over the external surface of the body possess properties of organic semiconductors; 3) 1 and 2 are piezoelectric, and are involved both in gravity orientation and transposition from photo to geotaxis

    Case report: Malignant hypertension associated with catecholamine excess in a patient with Leigh syndrome

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    BACKGROUND: Leigh syndrome is a progressive neurodegenerative mitochondrial disorder caused by multiple genetic etiologies with multisystemic involvement that mostly affecting the central nervous system with high rate of premature mortality. CASE PRESENTATION: We present a 3-year, 10 month-old female patient with Leigh syndrome complicated by renal tubular acidosis, hypertension, gross motor delay, who presented with hypertensive emergency, persistent tachycardia, insomnia and irritability. Her previous genetic workup revealed a pathogenic variant in the MT-ND5 gene designated as m.13513G \u3e A;p.Asp393Asn with a heteroplasmy of 69%. She presented acutely with malignant hypertension requiring intensive care unit admission. Her acute evaluation revealed elevated serum and urine catecholamines, without an identifiable catecholamine-secreting tumor. After extensive evaluation for secondary causes, she was ultimately found to have progression of her disease with new infarctions in her medulla, pons, and basal ganglia as the most likely etiology of her hypertension. She was discharged home with clonidine, amlodipine and atenolol for hypertension management. This report highlights the need to recognize possible autonomic dysfunction in mitochondrial disease and illustrates the challenges for accurate and prompt diagnosis and subsequent management of the associated manifestations. This association between catecholamine induced autonomic dysfunction and Leigh syndrome has been previously reported only once with MT-ND5 mutation. CONCLUSIONS: Elevated catecholamines with malignant secondary hypertension may be unique to this specific mutation or may be a previously unrecognized feature of Leigh syndrome and other mitochondrial complex I deficient syndromes. As such, patients with Leigh syndrome who present with malignant hypertension should be treated without the need for extensive work-up for catecholamine-secreting tumors

    Bell inequalities for random fields

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    The assumptions required for the derivation of Bell inequalities are not usually satisfied for random fields in which there are any thermal or quantum fluctuations, in contrast to the general satisfaction of the assumptions for classical two point particle models. Classical random field models that explicitly include the effects of quantum fluctuations on measurement are possible for experiments that violate Bell inequalities.Comment: 18 pages; 1 figure; v4: Essentially the published version; extensive improvements. v3: Better description of the relationship between classical random fields and quantum fields; better description of random field models. More extensive references. v2: Abstract and introduction clarifie

    Comment on "Consistency, amplitudes, and probabilities in quantum theory"

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    In a recent article [Phys. Rev. A 57, 1572 (1998)] Caticha has concluded that ``nonlinear variants of quantum mechanics are inconsistent.'' In this note we identify what it is that nonlinear quantum theories have been shown to be inconsistent with.Comment: LaTeX, 5 pages, no figure

    Bounds on Multipartite Entangled Orthogonal State Discrimination Using Local Operations and Classical Communication

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    We show that entanglement guarantees difficulty in the discrimination of orthogonal multipartite states locally. The number of pure states that can be discriminated by local operations and classical communication is bounded by the total dimension over the average entanglement. A similar, general condition is also shown for pure and mixed states. These results offer a rare operational interpretation for three abstractly defined distance like measures of multipartite entanglement.Comment: 4 pages, 1 figure. Title changed in accordance with jounral request. Major changes to the paper. Intro rewritten to make motivation clear, and proofs rewritten to be clearer. Picture added for clarit

    Bell's theorem as a signature of nonlocality: a classical counterexample

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    For a system composed of two particles Bell's theorem asserts that averages of physical quantities determined from local variables must conform to a family of inequalities. In this work we show that a classical model containing a local probabilistic interaction in the measurement process can lead to a violation of the Bell inequalities. We first introduce two-particle phase-space distributions in classical mechanics constructed to be the analogs of quantum mechanical angular momentum eigenstates. These distributions are then employed in four schemes characterized by different types of detectors measuring the angular momenta. When the model includes an interaction between the detector and the measured particle leading to ensemble dependencies, the relevant Bell inequalities are violated if total angular momentum is required to be conserved. The violation is explained by identifying assumptions made in the derivation of Bell's theorem that are not fulfilled by the model. These assumptions will be argued to be too restrictive to see in the violation of the Bell inequalities a faithful signature of nonlocality.Comment: Extended manuscript. Significant change

    Testing the Dirac equation

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    The dynamical equations which are basic for the description of the dynamics of quantum felds in arbitrary space--time geometries, can be derived from the requirements of a unique deterministic evolution of the quantum fields, the superposition principle, a finite propagation speed, and probability conservation. We suggest and describe observations and experiments which are able to test the unique deterministic evolution and analyze given experimental data from which restrictions of anomalous terms violating this basic principle can be concluded. One important point is, that such anomalous terms are predicted from loop gravity as well as from string theories. Most accurate data can be obtained from future astrophysical observations. Also, laboratory tests like spectroscopy give constraints on the anomalous terms.Comment: 11 pages. to appear in: C. L\"ammerzahl, C.W.F. Everitt, and F.W. Hehl (eds.): Gyros, Clocks, Interferometers...: Testing Relativistic Gravity in Space, Lecture Notes in Physics 562, Springer 200

    Does quantum nonlocality irremediably conflict with Special Relativity?

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    We reconsider the problem of the compatibility of quantum nonlocality and the requests for a relativistically invariant theoretical scheme. We begin by discussing a recent important paper by T. Norsen [arXiv:0808.2178] on this problem and we enlarge our considerations to give a general picture of the conceptually relevant issue to which this paper is devoted.Comment: 18 pages, 1 figur

    Non-local Realistic Theories and the Scope of the Bell Theorem

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    According to a widespread view, the Bell theorem establishes the untenability of so-called 'local realism'. On the basis of this view, recent proposals by Leggett, Zeilinger and others have been developed according to which it can be proved that even some non-local realistic theories have to be ruled out. As a consequence, within this view the Bell theorem allows one to establish that no reasonable form of realism, be it local or non-local, can be made compatible with the (experimentally tested) predictions of quantum mechanics. In the present paper it is argued that the Bell theorem has demonstrably nothing to do with the 'realism' as defined by these authors and that, as a consequence, their conclusions about the foundational significance of the Bell theorem are unjustified.Comment: Forthcoming in Foundations of Physic

    A probabilistic phase-insensitive optical squeezer in peaceful coexistence with causality

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    A non trace-preserving map describing a probabilistic but heralded noiseless linear amplifier has recently been proposed and experimentally demonstrated. Here, we exhibit another remarkable feature of this peculiar transformation, namely its ability to serve as a universal single-mode squeezer regardless of the quadrature that is initially squeezed. Hence, it acts as an heralded phase-insensitive optical squeezer, conserving the signal-to-noise ratio just as a phase-sensitive optical amplifier but for all quadratures at the same time, which may offer new perspectives in quantum optical communications. Although this ability to squeeze all quadratures seemingly opens a way to instantaneous signaling by circumventing the quantum no-cloning theorem, we explain the subtle mechanism by which the probability for such a causality violation vanishes, even on an heralded basis
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