78 research outputs found
Spin-Transfer-Torque Driven Magneto-Logic OR, AND and NOT Gates
We show that current induced magneto-logic gates like AND, OR and NOT can be
designed with the simple architecture involving a single nano spin-valve
pillar, as an extension of our recent work on spin-torque-driven magneto-logic
universal gates, NAND and NOR. Here the logical operation is induced by
spin-polarized currents which also form the logical inputs. The operation is
facilitated by the simultaneous presence of a constant controlling magnetic
field, in the absence of which the same element operates as a magnetoresistive
memory element. We construct the relevant phase space diagrams for the free
layer magnetization dynamics in the monodomain approximation and show the
rationale and functioning of the proposed gates. The flipping time for the
logical states of these non-universal gates is estimated to be within nano
seconds, just like their universal counter parts.Comment: 9 pages,7 figure
DDoS Attack Detection in WSN using Modified Invasive Weed Optimization with Extreme Learning Machine
Wireless sensor networks (WSN) are the wide-spread methodology for its distribution of the vast amount of devoted sensor nodes (SNs) that is employed for sensing the atmosphere and gather information. The gathered information was transmitted to the sink nodes via intermediate nodes. Meanwhile, the SN data are prone to the internet, and they are vulnerable to diverse security risks, involving distributed denial of service (DDoS) outbreaks that might interrupt network operation and compromises data integrity. In recent times, developed machine learning (ML) approaches can be applied for the discovery of DDoS attacks and accomplish security in WSN. To achieve this, this study presents a modified invasive weed optimization with extreme learning machine (MIWO-ELM) model for DDoS outbreak recognition in the WSN atmosphere. In the presented MIWO-ELM technique, an initial stage of data pre-processing is conducted. The ELM model can be applied for precise DDoS attack detection and classification process. At last, the MIWO method can be exploited for the parameter tuning of the ELM model which leads to improved performance of the classification. The experimental analysis of the MIWO-ELM method takes place using WSN dataset. The comprehensive simulation outputs show the remarkable performance of the MIWO-ELM method compared to other recent approaches
Daily rhythm of nociception in rats
BACKGROUND: Many behavioral and physiological variables exhibit daily rhythmicity. Few investigations of the daily rhythmicity in nociception have been conducted, and conflicting results have been obtained. The present study evaluated the daily rhythmicity in nociception in Wistar rats. METHODS: Nociception was investigated by Eddy's hot plate method, tail immersion method, and tail clip method. The latency between the noxious stimulus and the animal's response was recorded as reaction time. Separate groups of rats were tested in 4-hour intervals for 24 hours. RESULTS: There was clear daily variation in response latency. Reaction time was shortest a few hours before lights-on and longest at the light-dark transition. CONCLUSION: Nociception exhibits robust daily rhythmicity in rats. Sensitivity to pain is highest late in the dark phase of the light-dark cycle and lowest at the light-dark transition
Genetic evidence that SOST inhibits WNT signaling in the limb
AbstractSOST is a negative regulator of bone formation, and mutations in human SOST are responsible for sclerosteosis. In addition to high bone mass, sclerosteosis patients occasionally display hand defects, suggesting that SOST may function embryonically. Here we report that overexpression of SOST leads to loss of posterior structures of the zeugopod and autopod by perturbing anteriorâposterior and proximalâdistal signaling centers in the developing limb. Mutant mice that overexpress SOST in combination with Grem1 and Lrp6 mutations display more severe limb defects than single mutants alone, while Sostâ/â significantly rescues the Lrp6â/â skeletal phenotype, signifying that SOST gain-of-function impairs limb patterning by inhibiting the WNT signaling through LRP5/6
Equatorial and related non-equilibrium states in magnetization dynamics of ferromagnets: Generalization of Suhl's spin-wave instabilities
We investigate the nonlinear dynamics underlying the evolution of a 2-D
nanoscale ferromagnetic film with uniaxial anisotropy in the presence of
perpendicular pumping. Considering the associated Landau-Lifshitz spin
evolution equation with Gilbert damping together with Maxwell equation for the
demagnetization field, we study the dynamics in terms of the stereographic
variable. We identify several new fixed points for suitable choice of external
field in a rotating frame of reference. In particular, we identify explicit
equatorial and related fixed points of the spin vector in the plane transverse
to the anisotropy axis when the pumping frequency coincides with the amplitude
of the static parallel field. We then study the linear stability of these novel
fixed points under homogeneous and spin wave perturbations and obtain a
generalized Suhl's instability criterion, giving the condition for exponential
growth of P-modes under spin wave perturbations. Two parameter phase diagrams
(in terms of amplitudes of static parallel and oscillatory perpendicular
magnetic fields) for stability are obtained, which differ qualitatively from
those for the conventional ferromagnetic resonance near thermal equilibrium and
are amenable to experimental tests.Comment: 23 pages, 5 figures, To appear in Physica
Vhl deficiency in osteocytes produces high bone mass and hematopoietic defects
Tissue oxygen (O2) levels vary during development and disease; adaptations to decreased O2 (hypoxia) are mediated by hypoxia-inducible factor (HIF) transcription factors. HIFs are active in the skeleton, and stabilizing HIF-α isoforms cause high bone mass (HBM) phenotypes. A fundamental limitation of previous studies examining the obligate role for HIF-α isoforms in the skeleton involves the persistence of gene deletion as osteolineage cells differentiate into osteocytes. Because osteocytes orchestrate skeletal development and homeostasis, we evaluated the influence of Vhl or Hif1a disruption in osteocytes. Osteocytic Vhl deletion caused HBM phenotype, but Hif1a was dispensable in osteocytes. Vhl cKO mice revealed enhanced canonical Wnt signaling. B cell development was reduced while myelopoiesis increased in osteocytic Vhl cKO, revealing a novel influence of Vhl/HIF-α function in osteocytes on maintenance of bone microarchitecture via canonical Wnt signaling and effects on hematopoiesis
Nonlinear Dynamics of Moving Curves and Surfaces: Applications to Physical Systems
The subject of moving curves (and surfaces) in three dimensional space (3-D)
is a fascinating topic not only because it represents typical nonlinear
dynamical systems in classical mechanics, but also finds important applications
in a variety of physical problems in different disciplines. Making use of the
underlying geometry, one can very often relate the associated evolution
equations to many interesting nonlinear evolution equations, including soliton
possessing nonlinear dynamical systems. Typical examples include dynamics of
filament vortices in ordinary and superfluids, spin systems, phases in
classical optics, various systems encountered in physics of soft matter, etc.
Such interrelations between geometric evolution and physical systems have
yielded considerable insight into the underlying dynamics. We present a
succinct tutorial analysis of these developments in this article, and indicate
further directions. We also point out how evolution equations for moving
surfaces are often intimately related to soliton equations in higher
dimensions.Comment: Review article, 38 pages, 7 figs. To appear in Int. Jour. of Bif. and
Chao
Conditional Deletion of Sost in MSCâderived lineages Identifies Specific Cell Type Contributions to Bone Mass and B Cell Development
Sclerostin (Sost) is a negative regulator of bone formation and blocking its function via antibodies has shown great therapeutic promise by increasing both bone mass in humans and animal models. Sclerostin deletion in Sost knockout mice (Sostâ/â) causes high bone mass (HBM) similar to Sclerosteosis patients. Sostâ/â mice have been shown to display an up to 300% increase in bone volume/total volume (BV/TV), relative to aged matched controls, and it has been postulated that the main source of skeletal Sclerostin is the osteocyte. To understand the cellâtype specific contributions to the HBM phenotype described in Sostâ/â mice, as well as to address the endocrine and paracrine mode of action of sclerostin, we examined the skeletal phenotypes of conditional Sost lossâofâfunction (SostiCOIN/iCOIN) mice with specific deletions in (1) the limb mesenchyme (Prx1âCre; targets osteoprogenitors and their progeny); (2) midâstage osteoblasts and their progenitors (Col1âCre); (3) mature osteocytes (Dmp1âCre) and (4) hypertrophic chondrocytes and their progenitors (ColXâCre). All conditional alleles resulted in significant increases in bone mass in trabecular bone in both the femur and lumbar vertebrae, but only Prx1âCre deletion fully recapitulated the amplitude of the HBM phenotype in the appendicular skeleton and the B cell defect described in the global knockout. Despite wildtype expression of Sost in the axial skeleton of Prx1âCre deleted mice, these mice also had a significant increase in bone mass in the vertebrae, but the Sclerostin released in circulation by the axial skeleton did not affect bone parameters in the appendicular skeleton. Also, both Col1 and Dmp1 deletion resulted in a similar 80% significant increase in trabecular bone mass, but only Col1 and Prx1 deletion resulted in a significant increase in cortical thickness. We conclude that several cell types within the Prx1âosteoprogenitor derived lineages contribute significant amounts of Sclerostin protein to the paracrine pool of Sost, in bone
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