Measurement and control of a mechanical oscillator at its thermal decoherence rate

In real-time quantum feedback protocols, the record of a continuous measurement is used to stabilize a desired quantum state. Recent years have seen highly successful applications in a variety of well-isolated micro-systems, including microwave photons and superconducting qubits. By contrast, the ability to stabilize the quantum state of a tangibly massive object, such as a nanomechanical oscillator, remains a difficult challenge: The main obstacle is environmental decoherence, which places stringent requirements on the timescale in which the state must be measured. Here we describe a position sensor that is capable of resolving the zero-point motion of a solid-state, nanomechanical oscillator in the timescale of its thermal decoherence, a critical requirement for preparing its ground state using feedback. The sensor is based on cavity optomechanical coupling, and realizes a measurement of the oscillator's displacement with an imprecision 40 dB below that at the standard quantum limit, while maintaining an imprecision-back-action product within a factor of 5 of the Heisenberg uncertainty limit. Using the measurement as an error signal and radiation pressure as an actuator, we demonstrate active feedback cooling (cold-damping) of the 4.3 MHz oscillator from a cryogenic bath temperature of 4.4 K to an effective value of 1.1$\pm$0.1 mK, corresponding to a mean phonon number of 5.3$\pm$0.6 (i.e., a ground state probability of 16%). Our results set a new benchmark for the performance of a linear position sensor, and signal the emergence of engineered mechanical oscillators as practical subjects for measurement-based quantum control.Comment: 24 pages, 10 figures; typos corrected in main text and figure

Multivalued linear transformations of hyperspaces

The purpose of this paper is the study of multivalued linear transformations of hypervector spaces (or hyperspaces) in the sense of Tallini. In this regards first we introduce and study various multivalued linear transformations of hyperspaces and then constitute the categories of hyperspaces with respect the different linear transformations of hyperspaces as the morphisms in these categories. Also, we construct some algebraic hyperoperations on Hom K (V,W), the set of all multivalued linear transformations from a hyperspace V into hyperspaces W, and obtaine their basic properties. Finally, we construct the fundamental functor F from HV K , category of hyperspaces over field K into V K , the category of clasical vector space over K

Core promoter short tandem repeats as evolutionary switch codes for primate speciation

Alteration in gene expression levels underlies many of the phenotypic differences across species. Because of their highly mutable nature, proximity to the +1 transcription start site (TSS), and the emerging evidence of functional impact on gene expression, core promoter short tandem repeats (STRs) may be considered an ideal source of variation across species. In a genome-scale analysis of the entire Homo sapiens protein-coding genes, we have previously identified core promoters with at least one STR of ≥6-repeats, with possible selective advantage in this species. In the current study, we performed reverse analysis of the entire Homo sapiens orthologous genes in mouse in the Ensembl database, in order to identify conserved STRs that have shrunk as an evolutionary advantage to humans. Two protocols were used to minimize ascertainment bias. Firstly, two species sharing a more recent ancestor with Homo sapiens (i.e. Pan troglodytes and Gorilla gorilla gorilla) were also included in the study. Secondly, four non-primate species encompassing the major orders across Mammals, including Scandentia, Laurasiatheria, Afrotheria, and Xenarthra were analyzed as out-groups. We introduce STR evolutionary events specifically identical in primates (i.e. Homo sapiens, Pan troglodytes, and Gorilla gorilla gorilla) vs. non-primate out-groups. The average frequency of the identically shared STR motifs across those primates ranged between 0.00005 and 0.06. The identified genes are involved in important evolutionary and developmental processes, such as normal craniofacial development (TFAP2B), regulation of cell shape (PALMD), learning and long-term memory (RGS14), nervous system development (GFRA2), embryonic limb morphogenesis (PBX2), and forebrain development (APAF1). We provide evidence of core promoter STRs as evolutionary switch codes for primate speciation, and the first instance of identity-by-descent for those motifs at the interspecies level. © 2014 Wiley Periodicals, Inc

Preliminary Experimental Investigation on a Low Profile Magneto-Hydrodynamic Propulsive Blanket, Considering Plasma Generation

The use of magnetohydrodynamic (MHD) blanket propulsion system in ships, even with low efficiencies, has particular benefits that can make them an appropriate option for the marine designers. Accordingly, any attempt to increase the efficiency of these systems requires full recognition of their performance in different conditions. In the present study, as a continuation of previous numerical works by the current authors, a magneto-hydrodynamic blanket propulsion system has been built and experimentally studied through examining the MHD forces produced in different voltages. Copper and gold have been used and compared as electrodes and the high advantage of gold has been demonstrated. The effect of electrolysis on the behavior of the blanket is analyzed. It has been demonstrated that although electrolysis restricts high currents in lower voltages (lower than ~140V) and the saturation of hydrogen decreases the MHD forces due to low electrical current (~140V up to ~160V), the saturation of hydrogen around cathode at high voltages (more than ~160V), makes a dielectric barrier which soon breaks down and make the production of plasma possible, which in turn highly increases the thrust force of the MHD blanket. Therefore, three regimes have been introduced and described for the MHD blanket; the electrolysis regime, the transition regime, and the hot plasma regime. Based on the obtained results, one may conclude that the present results have offered good evidence about the possibility of increasing the MHD blanket performance through plasma production in water

Clamp-tapering increases the quality factor of stressed nanobeams

Stressed nanomechanical resonators are known to have exceptionally high quality factors ($Q$) due to the dilution of intrinsic dissipation by stress. Typically, the amount of dissipation dilution and thus the resonator $Q$ is limited by the high mode curvature region near the clamps. Here we study the effect of clamp geometry on the $Q$ of nanobeams made of high-stress $\mathrm{Si_3N_4}$. We find that tapering the beam near the clamp - and locally increasing the stress - leads to increased $Q$ of MHz-frequency low order modes due to enhanced dissipation dilution. Contrary to recent studies of tethered-membrane resonators, we find that widening the clamps leads to decreased $Q$ despite increased stress in the beam bulk. The tapered-clamping approach has practical advantages compared to the recently developed "soft-clamping" technique. Tapered-clamping enhances the $Q$ of the fundamental mode and can be implemented without increasing the device size

Peanut consumption and cardiovascular risk

Objective We evaluated the effects of peanut consumption on lipid profiles, atherogenic index of plasma (AIP) and CHD risk in hypercholesterolaemic men.Design Randomised crossover clinical trial.Setting Participants were randomly assigned to two groups. They were asked to consume peanut supplements (about 77 g) with their habitual diet for 4 weeks.Subjects Fifty-four hypercholesterolaemic men with total cholesterol (TC) concentrations between 200 and 350 mg/dl.Results Compared with the habitual diet, peanut supplementation of the habitual diet significantly reduced TC/HDL cholesterol (HDL-C) ratio (mean 1 (se 03) P = 0001) and LDL cholesterol (LDL-C)/HDL-C ratio (mean 07 (se 02); P = 0001). Peanut consumption increased HDL-C (mean 61 (se 15) mg/dl; P < 0001) and total antioxidant capacity (TAC) (mean 12 (se 06) U/mL P = 004). In addition, peanut consumption significantly reduced the AIP (mean 01 (se 003) P = 001) and CHD estimated risk over 10 years based on systolic and diastolic blood pressures (mean 14 (se 05 ) P = 0004 and mean 22 (se 05 ) P < 0001, respectively).Conclusions Short-term peanut consumption might improve lipid profiles, the AIP and CHD risk in free-living hypercholesterolaemic men. © 2009 The Authors

Epidemiological characteristics of human brucellosis in Shahin Dezh, Western Azarbaijan, Iran, 2008-2012

Background: Brucellosis is still one of the most challenging issues for health and the economy in many developing countries such as Iran. Objectives: This study investigated the epidemiological features of brucellosis in Shahin Dezh, Western Azarbaijan province, North West of Iran. Patients and Methods: This study had across-sectional design and data was collected from private and public sectors over a five-year period (2008-2012). All cases were studied between years 2008 and 2012 in Shahin Dezh. Results: In total, 492 cases of brucellosis were reported. The prevalence of brucellosis decreased from 152 cases/100000 inhabitants in 2008 to 97 cases/100000 inhabitants at the beginning of 2012. About 52.3 of subjects were male, and most cases of brucellosis were aged 25-30 years. Eighty-one percent of subjects lived in rural areas. There was a statistically significant difference regarding contact with livestock between rural and urban areas (91.7 vs. 68.8) (P value <0.001). Raw milk was the most commonly consumed dairy product; consumed by 37 of cases. Finally, during winter and spring a high prevalence rate of brucellosis was reported. Conclusions: Comprehensive health-related interventions need to empower communities at risk, especially young men and young and adult women in the Shahin Dezh County. Health education is needed to raise awareness of people in the studied area. © 2015, Infectious Diseases and Tropical Medicine Research Center