2,213 research outputs found

    Chilopodes cavernicoles et endogés de l'île de Majorque.

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    Living IoT: A Flying Wireless Platform on Live Insects

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    Sensor networks with devices capable of moving could enable applications ranging from precision irrigation to environmental sensing. Using mechanical drones to move sensors, however, severely limits operation time since flight time is limited by the energy density of current battery technology. We explore an alternative, biology-based solution: integrate sensing, computing and communication functionalities onto live flying insects to create a mobile IoT platform. Such an approach takes advantage of these tiny, highly efficient biological insects which are ubiquitous in many outdoor ecosystems, to essentially provide mobility for free. Doing so however requires addressing key technical challenges of power, size, weight and self-localization in order for the insects to perform location-dependent sensing operations as they carry our IoT payload through the environment. We develop and deploy our platform on bumblebees which includes backscatter communication, low-power self-localization hardware, sensors, and a power source. We show that our platform is capable of sensing, backscattering data at 1 kbps when the insects are back at the hive, and localizing itself up to distances of 80 m from the access points, all within a total weight budget of 102 mg.Comment: Co-primary authors: Vikram Iyer, Rajalakshmi Nandakumar, Anran Wang, In Proceedings of Mobicom. ACM, New York, NY, USA, 15 pages, 201

    Positive temperature versions of two theorems on first-passage percolation

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    The estimates on the fluctuations of first-passsage percolation due to Talagrand (a tail bound) and Benjamini--Kalai--Schramm (a sublinear variance bound) are transcribed into the positive-temperature setting of random Schroedinger operators.Comment: 15 pp; to appear in GAFA Seminar Note

    The Error and Repair Catastrophes: A Two-Dimensional Phase Diagram in the Quasispecies Model

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    This paper develops a two gene, single fitness peak model for determining the equilibrium distribution of genotypes in a unicellular population which is capable of genetic damage repair. The first gene, denoted by σvia \sigma_{via} , yields a viable organism with first order growth rate constant k>1 k > 1 if it is equal to some target ``master'' sequence σvia,0 \sigma_{via, 0} . The second gene, denoted by σrep \sigma_{rep} , yields an organism capable of genetic repair if it is equal to some target ``master'' sequence σrep,0 \sigma_{rep, 0} . This model is analytically solvable in the limit of infinite sequence length, and gives an equilibrium distribution which depends on \mu \equiv L\eps , the product of sequence length and per base pair replication error probability, and \eps_r , the probability of repair failure per base pair. The equilibrium distribution is shown to exist in one of three possible ``phases.'' In the first phase, the population is localized about the viability and repairing master sequences. As \eps_r exceeds the fraction of deleterious mutations, the population undergoes a ``repair'' catastrophe, in which the equilibrium distribution is still localized about the viability master sequence, but is spread ergodically over the sequence subspace defined by the repair gene. Below the repair catastrophe, the distribution undergoes the error catastrophe when μ \mu exceeds \ln k/\eps_r , while above the repair catastrophe, the distribution undergoes the error catastrophe when μ \mu exceeds lnk/fdel \ln k/f_{del} , where fdel f_{del} denotes the fraction of deleterious mutations.Comment: 14 pages, 3 figures. Submitted to Physical Review

    High frequency dynamics in a monatomic glass

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    The high frequency dynamics of glassy Selenium has been studied by Inelastic X-ray Scattering at beamline BL35XU (SPring-8). The high quality of the data allows one to pinpoint the existence of a dispersing acoustic mode for wavevectors (QQ) of 1.5<Q<12.51.5<Q<12.5 nm1^{-1}, helping to clarify a previous contradiction between experimental and numerical results. The sound velocity shows a positive dispersion, exceeding the hydrodynamic value by \approx 10% at Q<3.5Q<3.5 nm1^{-1}. The Q2Q^2 dependence of the sound attenuation Γ(Q)\Gamma(Q), reported for other glasses, is found to be the low-QQ limit of a more general Γ(Q)Ω(Q)2\Gamma(Q) \propto \Omega(Q)^2 law which applies also to the higher QQ region, where Ω(Q)Q\Omega(Q)\propto Q no longer holds.Comment: Phys. Rev. Lett. (Accepted

    Crystal structure and proton conductivity of BaZr0.9Sc0

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    Solid-state sintering has been used to prepare the perovskite BaZr0.9Sc0.1O3-delta. Analysis of X-ray powder diffraction data shows that an increase of the unit cell parameter, a, was observed after deuteration. Rietveld analysis of room-temperature neutron powder diffraction data confirmed cubic symmetry (space group Pm-3m). Dynamic thermogravimetric analysis indicates that the hydration process occurs below 335 degrees C and approximately 58% of the theoretical number of protonic defects can be filled. The presence of protons/deutrons is seen from the strong O-H/O-D stretch band in the infrared spectrum of the hydrated/deuterated samples. The proton conductivity of a prehydrated sample was investigated under dry and wet Ar atmosphere

    Identification of <i>Salvia haenkei</i> as gerosuppressant agent by using an integrated senescence-screening assay.

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    Cellular senescence is a stable cell cycle arrest that is the causative process of aging. The PI3K/AKT/mTOR pathway is implicated in the control of cellular senescence and inhibitors of this pathway have been successfully used for life span prolongation experiments in mammals. PTEN is the major regulator of the PI3K/AKT/mTOR pathway and loss of PTEN promotes a senescence response termed PICS. Here we report a novel-screening assay, for the identification of compounds that block different types of senescence response. By testing a library of more than 3000 natural and chemical compounds in PTEN deficient cells we have found that an extract from &lt;i&gt;Salvia haenkei&lt;/i&gt; (SH), a native plant of Bolivia is a potent inhibitor of PICS. SH also decreases replicative and UV-mediated senescence in human primary fibroblasts and in a model of &lt;i&gt;in vitro&lt;/i&gt; reconstructed human epidermis. Mechanistically, SH treatment affects senescence driven by UV by interfering with IL1-α signalling. Pre-clinical and clinical testing of this extract by performing toxicity and irritability evaluation &lt;i&gt;in vitro&lt;/i&gt; also demonstrate the safety of SH extract for clinical use as anti-aging skin treatment

    Nuclear receptors in vascular biology

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    Nuclear receptors sense a wide range of steroids and hormones (estrogens, progesterone, androgens, glucocorticoid, and mineralocorticoid), vitamins (A and D), lipid metabolites, carbohydrates, and xenobiotics. In response to these diverse but critically important mediators, nuclear receptors regulate the homeostatic control of lipids, carbohydrate, cholesterol, and xenobiotic drug metabolism, inflammation, cell differentiation and development, including vascular development. The nuclear receptor family is one of the most important groups of signaling molecules in the body and as such represent some of the most important established and emerging clinical and therapeutic targets. This review will highlight some of the recent trends in nuclear receptor biology related to vascular biology
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