Observations of temporal group delays in slow-light multiple coupled photonic crystal cavities

We demonstrate temporal group delays in coherently-coupled high-Q multi-cavity photonic crystals, in an all-optical analogue to electromagnetically induced transparency. We report deterministic control of the group delay up to 4× the single cavity lifetime in our CMOS-fabricated room-temperature chip. Supported by three-dimensional numerical simulations and theoretical analyses, our multi-pump beam approach enables control of the multi-cavity resonances and inter-cavity phase, in both single and double transparency peaks. The standing-wave wavelength-scale photon localization allows direct scalability for chip-scale optical pulse trapping and coupled-cavity QED

Long-term degradation of optical devices on the moon

Forty years ago, Apollo astronauts placed the first of several retroreflector arrays on the lunar surface. Their continued usefulness for laser-ranging might suggest that the lunar environment does not damage optical devices. However, new laser ranging data reveal that the efficiency of the three Apollo reflector arrays is now diminished by a factor of ten at all lunar phases and by an additional factor of ten when the lunar phase is near full moon. These deficits did not exist in the earliest years of lunar ranging, indicating that the lunar environment damages optical equipment on the timescale of decades. Dust or abrasion on the front faces of the corner-cube prisms may be responsible, reducing their reflectivity and degrading their thermal performance when exposed to face-on sunlight at full moon. These mechanisms can be tested using laboratory simulations and must be understood before designing equipment destined for the moon.Comment: 9 pages; 4 figures; accepted for publication in Icaru

Authors' reply: Effect of preoperative oral antibiotics in combination with mechanical bowel preparation on inflammatory response and short-term outcomes following left-sided colonic and rectal resections

No abstract available

Effect of preoperative oral antibiotics in combination with mechanical bowel preparation on inflammatory response and short‐term outcomes following left‐sided colonic and rectal resections

Background: Preoperative oral antibiotics in addition to intravenous antibiotics and mechanical bowel preparation (MBP) may influence the gut microbiome and reduce both the postoperative systemic inflammatory response to surgery and postoperative infective complications following colorectal resection. This propensity score‐matched study compared outcomes of patients undergoing left‐sided colonic or rectal resection with or without a combination of oral antibiotics and MBP. Methods: The addition of oral antibiotics and MBP to prophylactic intravenous antibiotics in left‐sided colonic and rectal resections was introduced in 2015–2016 at a single institution. Propensity score matching was undertaken to compare the effects of oral antibiotics plus MBP versus neither oral antibiotics nor MBP on the postoperative systemic inflammatory response and short‐term outcomes in patients undergoing left‐sided colonic or rectal resection between 2013 and 2018. Results: Of 396 patients who had propensity score matching for host, anaesthetic and operative factors, 204 matched patients were identified. The addition of oral antibiotics and MBP was associated with a significantly reduced postoperative inflammatory response (reduced postoperative Glasgow Prognostic Score) on day 3 (odds ratio (OR) 0·66, 95 per cent c.i. 0·44 to 0·99; P  = 0·013) and day 4 (OR 0·46, 0·30 to 0·71; P  = 0·001). Significantly reduced overall complications (OR 0·31, 0·17 to 0·56; P  < 0·001), infective complications (OR 0·41, 0·22 to 0·77; P  = 0·011), surgical‐site infection (OR 0·37, 0·17 to 0·83; P  = 0·024) and postoperative length of hospital stay (median 7 days versus 8 days in patients who had intravenous antibiotics alone; P  = 0·050) were also observed. Conclusion: Preoperative oral antibiotics and MBP in addition to prophylactic intravenous antibiotics were associated with a reduction in the postoperative systemic inflammatory response and postoperative complications in patients undergoing resectional left‐sided colonic or rectal surgery

High Pressure Study on MgB2

The hydrostatic pressure effect on the newly discovered superconductor MgB2 has been determined. The transition temperature Tc was found to decrease linearly at a large rate of -1.6 K/GPa, in good quantitative agreement with the ensuing calculated value of -1.4 K/GPa within the BCS framework by Loa and Syassen, using the full-potential linearlized augmented plane-wave method. The relative pressure coefficient, dlnTc/dp, for MgB2 also falls between the known values for conventional sp- and d-superconductors. The observation, therefore, suggests that electron-phonon interaction plays a significant role in the superconductivity of the compound.Comment: 8 pages, 3 figures; submitted to Physical Review B (February 14, 2001; revised March 21, 2001); minor modifications, including a discussion of the preprint by Vogt et a

Dependence of direct detection signals on the WIMP velocity distribution

The signals expected in WIMP direct detection experiments depend on the ultra-local dark matter distribution. Observations probe the local density, circular speed and escape speed, while simulations find velocity distributions that deviate significantly from the standard Maxwellian distribution. We calculate the energy, time and direction dependence of the event rate for a range of velocity distributions motivated by recent observations and simulations, and also investigate the uncertainty in the determination of WIMP parameters. The dominant uncertainties are the systematic error in the local circular speed and whether or not the MW has a high density dark disc. In both cases there are substantial changes in the mean differential event rate and the annual modulation signal, and hence exclusion limits and determinations of the WIMP mass. The uncertainty in the shape of the halo velocity distribution is less important, however it leads to a 5% systematic error in the WIMP mass. The detailed direction dependence of the event rate is sensitive to the velocity distribution. However the numbers of events required to detect anisotropy and confirm the median recoil direction do not change substantially.Comment: 21 pages, 7 figures, v2 version to appear in JCAP, minor change

Classical capacity of quantum channels with general Markovian correlated noise

The classical capacity of a quantum channel with arbitrary Markovian correlated noise is evaluated. For the general case of a channel with long-term memory, which corresponds to a Markov chain which does not converge to equilibrium, the capacity is expressed in terms of the communicating classes of the Markov chain. For an irreducible and aperiodic Markov chain, the channel is forgetful, and one retrieves the known expression for the capacity

High Pressure Studies on Fe-Pnictide Superconductors

A review of high-pressure studies on Fe-pnictide superconductors is given. The pressure effects on the magnetic and superconducting transitions are discussed for different classes of doped and undoped FeAs-compounds, ROFeAs (R = rare earth), AeFe2As2 (Ae = Ca, Sr, Ba), and AFeAs (A = Li, Na). Pressure tends to decrease the magnetic transition temperature in the undoped or only slightly doped compounds. The superconducting Tc increases with pressure for underdoped FeAs-pnictides, remains approximately constant for optimal doping, and decreases linearly in the overdoped range. The undoped LaOFeAs and AeFe2As2 become superconducting under pressure although nonhydrostatic pressure conditions seem to play a role in CaFe2As2. The superconductivity in the (undoped) AFeAs is explained as a chemical pressure effect due to the volume contraction caused by the small ionic size of the A-elements. The binary FeSe shows the largest pressure coefficient of Tc in the Se-deficient superconducting phase.Comment: submitted for publication in Physica C special issue on Fe-pnictide

Test-retest reliability and predictive validity of a juvenile guide dog behavior test

The ability to measure stable and consistent behavioral traits in dogs would facilitate selection and assessment of working dogs, such as guide dogs. Ideally, these measures should predict suitability for the working role from a young age. This study assessed test-retest reliability of a juvenile guide dog behavior test and predictive validity using qualification or withdrawal from guide dog training. Ninety-three guide dog puppies (52 female; 41 male) were tested at 5 (mean 4.78; ±0.73 SD) and 8 (mean 7.98; ±0.78 SD) months of age. The dogs were exposed to a sequence of 11 stimuli designed to assess the dogs’ reactions to meeting a stranger, obedience commands, body sensitivity, scavenging, and “animal” and human distractions. The behavior of dogs was digitally recorded and analyzed using an ethogram incorporating both frequency of behavior and specific reactions to stimuli. Test-retest reliability indicated interindividual consistency in many of the behavioral measures such as jumping, barking, and “low” greeting posture, as defined in our ethogram. Behavior measures that did not show interindividual consistency between tests included obedience responses, lip licking, body shaking, and scratching. Binary logistic regression models revealed 7 behavioral measures at 5 months and 5 measures at 8 months that were significantly associated with qualification or withdrawal. Uncorrelated measures and principal component scores of correlated measures were combined in a logistic regression model that showed great potential for predicting the probability of a dog qualifying or being withdrawn from guide dog training

Evaluation of an inflammation-based prognostic score in patients with inoperable pancreatic cancer

Background/Aims: Patients with pancreatic cancer have one of the poorest survival rates and selection of patients for active treatment remains problematical. The present study assesses the value of an inflammation-based score (Glasgow Prognostic Score, GPS) in patients with inoperable pancreatic cancer. Methods: The GPS was constructed as follows: patients with both an elevated C-reactive protein (>10 mg/l) and hypoalbuminaemia (<35 g/l) were allocated a score of 2. Patients in whom only 1 or none of these biochemical abnormalities was present were allocated a score of 1 or 0, respectively. Results: One hundred and eighty-seven patients were studied and 49 (26%) underwent an operative palliative bypass procedure. At the end of follow-up, 181 (97%) patients died, 17% of patients were alive at 12 months. On univariate analysis, age (p < 0.01), TNM stage (p < 0.001) and the GPS (p < 0.001) were significant predictors of survival. On multivariate survival analysis, stratified for bypass procedure, age (hazard ratio 1.53, 95%CI 1.12–2.10, p = 0.008), TNM stage (hazard ratio 1.70, 95%CI 1.33–2.18, p < 0.001) and the GPS (hazard ratio 1.72, 95%CI 1.40–2.11, p < 0.001) remained independent significant predictors of survival. Conclusion: At diagnosis, the presence of a systemic inflammatory response (as measured by the GPS) appears to be a useful indicator of poor outcome, independent of TNM stage, in patients with inoperable pancreatic cancer