181 research outputs found

    Dialogue, Praxis and the State: A Response to Richard Jackson

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    The article argues in favour of an engagement with state actors for critical terrorism scholars, challenging Richard Jackson's assertion that such engagement necessarily involves co-optation

    Testing collapse models with levitated nanoparticles: the detection challenge

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    We consider a nanoparticle levitated in a Paul trap in ultrahigh cryogenic vacuum, and look for the conditions which allow for a stringent noninterferometric test of spontaneous collapse models. In particular we compare different possible techniques to detect the particle motion. Key conditions which need to be achieved are extremely low residual pressure and the ability to detect the particle at ultralow power. We compare three different detection approaches based respectively on a optical cavity, optical tweezer and a electrical readout, and for each one we assess advantages, drawbacks and technical challenges

    Generation of Entanglement from Mechanical Rotation

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    Many phenomena and fundamental predictions, ranging from Hawking radiation to the early evolution of the Universe rely on the interplay between quantum mechanics and gravity or more generally, quantum mechanics in curved spacetimes. However, our understanding is hindered by the lack of experiments that actually allow us to probe quantum mechanics in curved spacetime in a repeatable and accessible way. Here we propose an experimental scheme for a photon that is prepared in a path superposition state across two rotating Sagnac interferometers that have different diameters and thus represent a superposition of two different spacetimes. We predict the generation of genuine entanglement even at low rotation frequencies and show how these effects could be observed even due to the Earth's rotation. These predictions provide an accessible platform in which to study the role of the underlying spacetime in the generation of entanglement

    Determination of depression risk factors in children and adolescents by regression tree methodology.

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    We used a regression tree method (RTM) to determine risks of depression in children/adolescents. The survey records of 4,143 children/adolescents in a study based in Mersin, Turkey served as data in this study, and multi-step, stratified, and cluster sampling were used. Effects of 24 variables (sex, smoking, parental problems, etc.) were evaluated on depression scores. The Child Beck Depression Inventory (CBDI) was used to determine the level of depression. Subjects were into 12 different groups based on magnitudes of mean depression scores. The interactions among 7 variables determined to be risk factors are shown on a schema. The STATISTICA (ver.6.0) package program was used for all computations. Although traditional statistical methods have often been used for analysis in this field, such approaches are associated with certain disadvantages such as missing values, ignorance of interaction effects, or restriction of the shape of the distribution. To avoid such disadvantages, we therefore suggest the use of the RTM in studies involving numerical-based outcome variables and for the investigation of a large number of variables and it may be more effective than traditional statistical methods in epidemiological studies which determine risk factors.</p

    Photon bunching in a rotating reference frame

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    Although quantum physics is well understood in inertial reference frames (flat spacetime), a current challenge is the search for experimental evidence of nontrivial or unexpected behavior of quantum systems in noninertial frames. Here, we present a novel test of quantum mechanics in a noninertial reference frame: we consider Hong-Ou-Mandel (HOM) interference on a rotating platform and study the effect of uniform rotation on the distinguishability of the photons. Both theory and experiments show that the rotational motion induces a relative delay in the photon arrival times at the exit beam splitter and that this delay is observed as a shift in the position of the HOM dip. This experiment can be extended to a full general relativistic test of quantum physics using satellites in Earth’s orbit and indicates a new route toward the use of photonic technologies for investigating quantum mechanics at the interface with relativity

    Creating atom-nanoparticle quantum superpositions

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    A nanoscale object evidenced in a nonclassical state of its center of mass will hugely extend the boundaries of quantum mechanics. To obtain a practical scheme for the same, we exploit a hitherto unexplored coupled system: an atom and a nanoparticle coupled by an optical field. We show how to control the center of mass of a large ∼ 500 -nm nanoparticle using the internal state of the atom so as to create, as well as detect, nonclassical motional states of the nanoparticle. Specifically, we consider a setup based on a silica nanoparticle coupled to a cesium atom and discuss a protocol for preparing and verifying a Schrödinger-cat state of the nanoparticle that does not require cooling to the motional ground state. We show that the existence of the superposition can be revealed using the Earth's gravitational field using a method that is insensitive to the most common sources of decoherence and works for any initial state of the nanoparticle

    Precession Motion in Levitated Optomechanics

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    We investigate experimentally the dynamics of a nonspherical levitated nanoparticle in a vacuum. In addition to translation and rotation motion, we observe the light torque-induced precession and nutation of the trapped particle. We provide a theoretical model, which we numerically simulate and from which we derive approximate expressions for the motional frequencies. Both the simulation and approximate expressions we find in good agreement with experiments. We measure a torque of 1.9 � 0.5 × 10−23 N m at 1 × 10−1 mbar, with an estimated torque sensitivity of 3.6 � 1.1 × 10−31 N m= Hz p at 1 × 10−7 mba

    Testing collapse models with levitated nanoparticles: Detection challenge

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    We consider a nanoparticle levitated in a Paul trap in ultrahigh cryogenic vacuum, and look for the conditions which allow for a stringent noninterferometric test of spontaneous collapse models. In particular we compare different possible techniques to detect the particle motion. Key conditions which need to be achieved are extremely low residual pressure and the ability to detect the particle at ultralow power. We compare three different detection approaches based, respectively, on an optical cavity, an optical tweezer, and an electrical readout, and for each one we assess advantages, drawbacks, and technical challenges

    Reclaiming the political : emancipation and critique in security studies

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    The critical security studies literature has been marked by a shared commitment towards the politicization of security – that is, the analysis of its assumptions, implications and the practices through which it is (re)produced. In recent years, however, politicization has been accompanied by a tendency to conceive security as connected with a logic of exclusion, totalization and even violence. This has resulted in an imbalanced politicization that weakens critique. Seeking to tackle this situation, the present article engages with contributions that have advanced emancipatory versions of security. Starting with, but going beyond, the so-called Aberystwyth School of security studies, the argument reconsiders the meaning of security as emancipation by making the case for a systematic engagement with the notions of reality and power. This revised version of security as emancipation strengthens critique by addressing political dimensions that have been underplayed in the critical security literature

    Renal and suprarenal insufficiency secondary to familial Mediterranean fever associated with amyloidosis: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Familial Mediterranean fever is an autosomal recessive disease that predominantly affects people of the Mediterranean coast. One of the most frequent complications of the disease is amyloidosis. This clinical entity is known as secondary (also called AA) amyloidosis.</p> <p>Case presentation</p> <p>In this report, we describe the case of a 33-year-old Turkish man with familial Mediterranean fever and chronic renal insufficiency. He was admitted to our clinic with symptoms of suprarenal insufficiency. The patient died three months later as a result of cardiac arrest.</p> <p>Conclusion</p> <p>Our aim is to make a contribution to the literature by reporting a case of combined insufficiency due to the accumulation of renal and adrenal amyloid in a patient with familial Mediterranean fever, which has very rarely been described in the literature. We hope that adrenal insufficiency, which becomes fatal if not diagnosed and treated rapidly, will come to mind as easily as chronic renal failure in clinical practice.</p
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