Generalized susceptibility of quasi-one dimensional system with periodic potential: model for the organic superconductor (TMTSF)2_2ClO4_4

The nesting vector and the magnetic susceptibility of the quasi-one-dimensional system having imperfectly nested Fermi surface are studied analytically and numerically. The magnetic susceptibility has the plateau-like maximum in ``\textit{sweptback}'' region in the momentum space, which is surrounded by $\mathbf{Q}=(2 k_F, \pi) + \mathbf{q}_i$ ($k_F$ is the Fermi wave number, $i=1,3,4$, and $\mathbf{q}_1$, $\mathbf{q}_3$ and $\mathbf{q}_{4}$ are given in this paper). The best nesting vector, at which the susceptibility $\chi_0(\mathbf{Q})$ has the absolute maximum at T=0, is obtained near but not at the inflection point, $\mathbf{Q}=(2 k_F, \pi)+\mathbf{q}_4$. The effect of the periodic potential $V$ on the susceptibility is studied, which is important for the successive transitions of the field-induced spin density wave in (TMTSF)$_2$ClO$_4$. We obtain that the sweptback region (surrounded by $\mathbf{q}_2$, $\mathbf{q}_3$ and $\mathbf{q}_4$ when $V>0$) becomes small as $V$ increases and it shrinks to $\mathbf{q}_3$ for $V \geq 4 t_b'$, where $t_b'$ gives the degree of imperfect nesting of the Fermi surface, i.e. the second harmonics of the warping in the Fermi surface. The occurrence of the sign reversal of the Hall coefficient in the field-induced spin density wave states is discussed to be possible only when $V<2 t_b'-2 t_4$, where $t_4$ is the amplitude of the fourth harmonics of the warping in the Fermi surface. This gives the novel limitation for the magnitude of $V$

Hypotension due to Kir6.1 gain‐of‐function in vascular smooth muscle

BACKGROUND: K(ATP) channels, assembled from pore‐forming (Kir6.1 or Kir6.2) and regulatory (SUR1 or SUR2) subunits, link metabolism to excitability. Loss of Kir6.2 results in hypoglycemia and hyperinsulinemia, whereas loss of Kir6.1 causes Prinzmetal angina–like symptoms in mice. Conversely, overactivity of Kir6.2 induces neonatal diabetes in mice and humans, but consequences of Kir6.1 overactivity are unknown. METHODS AND RESULTS: We generated transgenic mice expressing wild‐type (WT), ATP‐insensitive Kir6.1 [Gly343Asp] (GD), and ATP‐insensitive Kir6.1 [Gly343Asp,Gln53Arg] (GD‐QR) subunits, under Cre‐recombinase control. Expression was induced in smooth muscle cells by crossing with smooth muscle myosin heavy chain promoter–driven tamoxifen‐inducible Cre‐recombinase (SMMHC‐Cre‐ER) mice. Three weeks after tamoxifen induction, we assessed blood pressure in anesthetized and conscious animals, as well as contractility of mesenteric artery smooth muscle and K(ATP) currents in isolated mesenteric artery myocytes. Both systolic and diastolic blood pressures were significantly reduced in GD and GD‐QR mice but normal in mice expressing the WT transgene and elevated in Kir6.1 knockout mice as well as in mice expressing dominant‐negative Kir6.1 [AAA] in smooth muscle. Contractile response of isolated GD‐QR mesenteric arteries was blunted relative to WT controls, but nitroprusside relaxation was unaffected. Basal K(ATP) conductance and pinacidil‐activated conductance were elevated in GD but not in WT myocytes. CONCLUSIONS: K(ATP) overactivity in vascular muscle can lead directly to reduced vascular contractility and lower blood pressure. We predict that gain of vascular K(ATP) function in humans would lead to a chronic vasodilatory phenotype, as indeed has recently been demonstrated in Cantu syndrome

Quantum state preparation and macroscopic entanglement in gravitational-wave detectors

Long-baseline laser-interferometer gravitational-wave detectors are operating at a factor of 10 (in amplitude) above the standard quantum limit (SQL) within a broad frequency band. Such a low classical noise budget has already allowed the creation of a controlled 2.7 kg macroscopic oscillator with an effective eigenfrequency of 150 Hz and an occupation number of 200. This result, along with the prospect for further improvements, heralds the new possibility of experimentally probing macroscopic quantum mechanics (MQM) - quantum mechanical behavior of objects in the realm of everyday experience - using gravitational-wave detectors. In this paper, we provide the mathematical foundation for the first step of a MQM experiment: the preparation of a macroscopic test mass into a nearly minimum-Heisenberg-limited Gaussian quantum state, which is possible if the interferometer's classical noise beats the SQL in a broad frequency band. Our formalism, based on Wiener filtering, allows a straightforward conversion from the classical noise budget of a laser interferometer, in terms of noise spectra, into the strategy for quantum state preparation, and the quality of the prepared state. Using this formalism, we consider how Gaussian entanglement can be built among two macroscopic test masses, and the performance of the planned Advanced LIGO interferometers in quantum-state preparation

Upper limits on the strength of periodic gravitational waves from PSR J1939+2134

The first science run of the LIGO and GEO gravitational wave detectors presented the opportunity to test methods of searching for gravitational waves from known pulsars. Here we present new direct upper limits on the strength of waves from the pulsar PSR J1939+2134 using two independent analysis methods, one in the frequency domain using frequentist statistics and one in the time domain using Bayesian inference. Both methods show that the strain amplitude at Earth from this pulsar is less than a few times $10^{-22}$.Comment: 7 pages, 1 figure, to appear in the Proceedings of the 5th Edoardo Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July 200

Improving the sensitivity to gravitational-wave sources by modifying the input-output optics of advanced interferometers

We study frequency dependent (FD) input-output schemes for signal-recycling interferometers, the baseline design of Advanced LIGO and the current configuration of GEO 600. Complementary to a recent proposal by Harms et al. to use FD input squeezing and ordinary homodyne detection, we explore a scheme which uses ordinary squeezed vacuum, but FD readout. Both schemes, which are sub-optimal among all possible input-output schemes, provide a global noise suppression by the power squeeze factor, while being realizable by using detuned Fabry-Perot cavities as input/output filters. At high frequencies, the two schemes are shown to be equivalent, while at low frequencies our scheme gives better performance than that of Harms et al., and is nearly fully optimal. We then study the sensitivity improvement achievable by these schemes in Advanced LIGO era (with 30-m filter cavities and current estimates of filter-mirror losses and thermal noise), for neutron star binary inspirals, and for narrowband GW sources such as low-mass X-ray binaries and known radio pulsars. Optical losses are shown to be a major obstacle for the actual implementation of these techniques in Advanced LIGO. On time scales of third-generation interferometers, like EURO/LIGO-III (~2012), with kilometer-scale filter cavities, a signal-recycling interferometer with the FD readout scheme explored in this paper can have performances comparable to existing proposals. [abridged]Comment: Figs. 9 and 12 corrected; Appendix added for narrowband data analysi

Search for gravitational wave bursts in LIGO's third science run

We report on a search for gravitational wave bursts in data from the three LIGO interferometric detectors during their third science run. The search targets subsecond bursts in the frequency range 100-1100 Hz for which no waveform model is assumed, and has a sensitivity in terms of the root-sum-square (rss) strain amplitude of hrss ~ 10^{-20} / sqrt(Hz). No gravitational wave signals were detected in the 8 days of analyzed data.Comment: 12 pages, 6 figures. Amaldi-6 conference proceedings to be published in Classical and Quantum Gravit

Searching for a Stochastic Background of Gravitational Waves with LIGO

The Laser Interferometer Gravitational-wave Observatory (LIGO) has performed the fourth science run, S4, with significantly improved interferometer sensitivities with respect to previous runs. Using data acquired during this science run, we place a limit on the amplitude of a stochastic background of gravitational waves. For a frequency independent spectrum, the new limit is $\Omega_{\rm GW} < 6.5 \times 10^{-5}$. This is currently the most sensitive result in the frequency range 51-150 Hz, with a factor of 13 improvement over the previous LIGO result. We discuss complementarity of the new result with other constraints on a stochastic background of gravitational waves, and we investigate implications of the new result for different models of this background.Comment: 37 pages, 16 figure

Effect of local anaesthesia and/or analgesia on pain responses induced by piglet castration

<p>Abstract</p> <p>Background</p> <p>Surgical castration in male piglets is painful and methods that reduce this pain are requested. This study evaluated the effect of local anaesthesia and analgesia on vocal, physiological and behavioural responses during and after castration. A second purpose was to evaluate if herdsmen can effectively administer anaesthesia.</p> <p>Methods</p> <p>Four male piglets in each of 141 litters in five herds were randomly assigned to one of four treatments: castration without local anaesthesia or analgesia (C, controls), analgesia (M, meloxicam), local anaesthesia (L, lidocaine), or both local anaesthesia and analgesia (LM). Lidocaine (L, LM) was injected at least three minutes before castration and meloxicam (M, LM) was injected after castration. During castration, vocalisation was measured and resistance movements judged. Behaviour observations were carried out on the castration day and the following day. The day after castration, castration wounds were ranked, ear and skin temperature was measured, and blood samples were collected for analysis of acute phase protein Serum Amyloid A concentration (SAA). Piglets were weighed on the castration day and at three weeks of age. Sickness treatments and mortality were recorded until three weeks of age.</p> <p>Results</p> <p>Piglets castrated with lidocaine produced calls with lower intensity (<it>p </it>< 0.001) and less resistance movements (<it>p </it>< 0.001) during castration. Piglets that were given meloxicam displayed less pain-related behaviour (huddled up, spasms, rump-scratching, stiffness and prostrated) on both the castration day (<it>p </it>= 0.06, n.s.) and the following day (<it>p </it>= 0.02). Controls had less swollen wounds compared to piglets assigned to treatments M, L and LM (<it>p </it>< 0.001). The proportion of piglets with high SAA concentration (over threshold values 200, 400 mg/l) was higher (<it>p </it>= 0.005; <it>p </it>= 0.05) for C + L compared to M + LM. Ear temperature was higher (<it>p </it>< 0.01) for controls compared to L and LM. There were no significant treatment effects for skin temperature, weight gain, sickness treatments or mortality.</p> <p>Conclusions</p> <p>The study concludes that lidocaine reduced pain during castration and that meloxicam reduced pain after castration. The study also concludes that the herdsmen were able to administer local anaesthesia effectively.</p