Effect of sound stress on ovulation, estrus, and conception in beef heifers

Thirty of the 50 heifers used in estrous synchronization studies and that received prostaglandin and Syncro-Mate B to synchronize estrus were subjected to sound stress for 48 hours after prostaglandin was injected. Fifty-nine percent of 29 sound-stressed heifers that showed estrus within 5 days conceived when artificially inseminated compared with 72 percent of 18 nonstressed heifers

Spin qubits with electrically gated polyoxometalate molecules

Spin qubits offer one of the most promising routes to the implementation of quantum computers. Very recent results in semiconductor quantum dots show that electrically-controlled gating schemes are particularly well-suited for the realization of a universal set of quantum logical gates. Scalability to a larger number of qubits, however, remains an issue for such semiconductor quantum dots. In contrast, a chemical bottom-up approach allows one to produce identical units in which localized spins represent the qubits. Molecular magnetism has produced a wide range of systems with tailored properties, but molecules permitting electrical gating have been lacking. Here we propose to use the polyoxometalate [PMo12O40(VO)2]q-, where two localized spins-1/2 can be coupled through the electrons of the central core. Via electrical manipulation of the molecular redox potential, the charge of the core can be changed. With this setup, two-qubit gates and qubit readout can be implemented.Comment: 9 pages, 6 figures, to appear in Nature Nanotechnolog

Dual-gated bilayer graphene hot electron bolometer

Detection of infrared light is central to diverse applications in security, medicine, astronomy, materials science, and biology. Often different materials and detection mechanisms are employed to optimize performance in different spectral ranges. Graphene is a unique material with strong, nearly frequency-independent light-matter interaction from far infrared to ultraviolet, with potential for broadband photonics applications. Moreover, graphene's small electron-phonon coupling suggests that hot-electron effects may be exploited at relatively high temperatures for fast and highly sensitive detectors in which light energy heats only the small-specific-heat electronic system. Here we demonstrate such a hot-electron bolometer using bilayer graphene that is dual-gated to create a tunable bandgap and electron-temperature-dependent conductivity. The measured large electron-phonon heat resistance is in good agreement with theoretical estimates in magnitude and temperature dependence, and enables our graphene bolometer operating at a temperature of 5 K to have a low noise equivalent power (33 fW/Hz1/2). We employ a pump-probe technique to directly measure the intrinsic speed of our device, >1 GHz at 10 K.Comment: 5 figure

Spintronics: Fundamentals and applications

Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.Comment: invited review, 36 figures, 900+ references; minor stylistic changes from the published versio

Circulating microRNA Profiles during the Bovine Oestrous Cycle

Up to 50% of ovulations go undetected in modern dairy herds due to attenuated oestrus behavior and a lack of high-accuracy methods for detection of fertile oestrus. This significantly reduces overall herd productivity and constitutes a high economic burden to the dairy industry. MicroRNAs (miRNAs) are ubiquitous regulators of gene expression during both health and disease and they have been shown to regulate different reproductive processes. Extracellular miRNAs are stable and can provide useful biomarkers of tissue function; changes in circulating miRNA profiles have been reported during menstrual cycles. This study sought to establish the potential of circulating miRNAs as biomarkers of oestrus in cattle. We collected plasma samples from 8 Holstein-Friesian heifers on days Days 0, 8 and 16 of an oestrous cycle and analysed small RNA populations on each Day using two independent high-throughput approaches, namely, Illumina sequencing (n = 24 samples) and Qiagen PCR arrays (n = 9 sample pools, 3-4 samples / pool). Subsequently, we used RT-qPCR (n = 24 samples) to validate the results of high-throughput analyses, as well as to establish the expression profiles of additional miRNAs previously reported to be differentially expressed during reproductive cycles. Overall, we identified four miRNAs (let-7f, miR-125b, miR-145 and miR-99a-5p), the plasma levels of which distinctly increased (up to 2.2-fold, P < 0.05) during oestrus (Day 0) relative to other stages of the cycle (Days 8 and 16). Moreover, we identified several hundred different isomiRs and established their relative abundance in bovine plasma. In summary, our results reveal the dynamic nature of plasma miRNAs during the oestrous cycle and provide evidence of the feasibility of using circulating miRNAs as biomarkers of reproductive function in livestock in the future

Semiconductor Spintronics

Spintronics refers commonly to phenomena in which the spin of electrons in a solid state environment plays the determining role. In a more narrow sense spintronics is an emerging research field of electronics: spintronics devices are based on a spin control of electronics, or on an electrical and optical control of spin or magnetism. This review presents selected themes of semiconductor spintronics, introducing important concepts in spin transport, spin injection, Silsbee-Johnson spin-charge coupling, and spindependent tunneling, as well as spin relaxation and spin dynamics. The most fundamental spin-dependent nteraction in nonmagnetic semiconductors is spin-orbit coupling. Depending on the crystal symmetries of the material, as well as on the structural properties of semiconductor based heterostructures, the spin-orbit coupling takes on different functional forms, giving a nice playground of effective spin-orbit Hamiltonians. The effective Hamiltonians for the most relevant classes of materials and heterostructures are derived here from realistic electronic band structure descriptions. Most semiconductor device systems are still theoretical concepts, waiting for experimental demonstrations. A review of selected proposed, and a few demonstrated devices is presented, with detailed description of two important classes: magnetic resonant tunnel structures and bipolar magnetic diodes and transistors. In most cases the presentation is of tutorial style, introducing the essential theoretical formalism at an accessible level, with case-study-like illustrations of actual experimental results, as well as with brief reviews of relevant recent achievements in the field.Comment: tutorial review; 342 pages, 132 figure

Effect of sound stress on ovulation, estrus, and conception in beef heifers

Thirty of the 50 heifers used in estrous synchronization studies and that received prostaglandin and Syncro-Mate B to synchronize estrus were subjected to sound stress for 48 hours after prostaglandin was injected. Fifty-nine percent of 29 sound-stressed heifers that showed estrus within 5 days conceived when artificially inseminated compared with 72 percent of 18 nonstressed heifers

Synchronizing estrus in heifers with prostaglandin and Syncro-mate B

Forty-seven of 50 heifers were in estrus 1 to 5 days after an injection of prostaglandin given when an ear implant of Synchro-mate B was removed. The implant had been in place one week. Thirty of the 47 (63.8%) heifers with synchronized estrus conceived on first artificial insemination. Twenty untreated heifers were in estrus in 27 days; 13 (65%) conceived on first artificial insemination

Insemination at an appointed time after estrous synchronization in beef cattle

Eighty-three cows were each treated with a nine-day Syncro-mate B ear implant and one estrogen and progesterone injection. After implant removal, cows were artificially inseminated either 48, 54 or 60 hours later or 12 hours after estrus. An additional 16 cows received no treatment and were pasture mated. First service conception rates were 26.3, 23.8, 38.1, 33.3, and 68.8% for the 48-, 54-, and 60-post implant group, 12-hour post-estrus, and naturally bred cows, respectively

Induced calving in beef cattle

Calving was induced in 44 Polled Hereford cows at 275 days’ gestation. Twenty mgs. Of dexamethasone (Azium) given intramuscularly caused parturition an average of 43.1 hours after injection (range 21 to 57). An injection of 30 mgs. Of prostaglandin F2 40 hours after dexamethasone effectively increased predictability of calving. Seven of nine cows calved 2.5 to five hours post prostaglandin (average time of calving 44.9 hours after dexamethasone). Prostaglandin given 30 hours after dexamethasone or dexamethasone 40 hours after prostaglandin was less effective ( average 46.6, range 34.5 to 57.5; average 75.3, range 63 to 100, respectively)