Dissemination of UTC(NIST) over 20 km of commercial optical fiber with active phase stabilization.

We demonstrate the transfer of a cesium frequency standard steered to UTC(NIST) over 20 km of dark telecom optical fiber. Our dissemination scheme uses an active stabilization technique with a phase-locked voltage-controlled oscillator. Out-of-loop characterization of the optical fiber link performance is done with dual-fiber and single-fiber transfer schemes. We observe a fractional frequency instability of 1.5 × 10-12 and 2 × 10-15 at averaging intervals of 1 s and 105 s, respectively, for the link. Both schemes are sufficient to transfer the cesium clock reference without degrading the signal, with nearly an order of magnitude lower fractional frequency instability than the cesium clocks over all time scales. The simplicity of the two-fiber technique may be useful in future long-distance applications where higher stability requirements are not paramount, as it avoids technical complications involved with the single-fiber scheme.

An environmental analysis of public UAP sightings and sky view potential.

Sightings of unidentified flying objects (UFOs) or unidentified anomalous phenomena (UAP) have been reported throughout history. Given the potential security and safety risks they pose, as well as scientific curiosity, there is increasing interest in understanding what these sighting reports represent. We approach this problem as an important one of the human experience and that can be examined through a geographical lens: what local factors may increase or decrease the number of sighting reports? Using a Bayesian regression method, we test hypotheses based on variables representing sky view potential (light pollution, tree canopy, and cloud cover) and the potential for objects to be present in the sky (aircraft and military installations). The dependent variable includes over 98,000 publicly reported UAP sightings in the conterminous United States during the 20-year period from 2001 to 2020. The model results find credible correlations between variables that suggest people see more "phenomena" when they have more opportunity to. This analysis is one of few investigations of UAP sighting reports at a national scale providing context to help examine individual reports. Given that these objects are labeled unidentifiable in the personal sense, there are many natural and/or human based explanations worth exploring.

Absolute Frequency Measurements of the D Lines in

Optical frequencies of the D line transitions in ^{9}Be^{+} were measured with a relative uncertainty of Δν/ν=5×10^{-11}. The results represent the highest accuracy achieved on a broad electric dipole-allowed (E1) transition in a trapped ion experiment to date, enabled in part by detailed consideration of photon recoil and quantum interference. Measurements were made on a single laser-cooled ion stored in a radio frequency Paul trap, using a spectroscopy laser stabilized to an optical frequency comb and referenced to UTC (NIST). The uncertainties in the D_{1} and D_{2} lines have been reduced by a factor of 10 and 30, respectively, compared to previous work. We have extracted the ^{2}P fine structure splitting, Δν_{fs}=197 064.54(7) MHz, and the ^{2}P_{1/2} hyperfine constant, A_{P_{1/2}}=-117.92(4) MHz.

Erratum:

This corrects the article DOI: 10.1103/PhysRevLett.123.033201.

Radium Ion Optical Clock.

We report the first operation of a Ra^{+} optical clock, a promising high-performance clock candidate. The clock uses a single trapped ^{226}Ra^{+} ion and operates on the 7s ^{2}S_{1/2}→6d ^{2}D_{5/2} electric quadrupole transition. By self-referencing three pairs of symmetric Zeeman transitions, we demonstrate a frequency instability of 1.1×10^{-13}/sqrt[τ], where τ is the averaging time in seconds. The total systematic uncertainty is evaluated to be Δν/ν=9×10^{-16}. Using the clock, we realize the first measurement of the ratio of the D_{5/2} state to the S_{1/2} state Landé g-factors: g_{D}/g_{S}=0.598 805 3(11). A Ra^{+} optical clock could improve limits on the time variation of the fine structure constant, α[over ˙]/α, in an optical frequency comparison. The ion also has several features that make it a suitable system for a transportable optical clock.

Quadruply Ionized Barium as a Candidate for a High-Accuracy Optical Clock.

We identify Ba^{4+} (Te-like) as a promising candidate for a high-accuracy optical clock. The lowest-lying electronic states are part of a ^{3}P_{J} fine structure manifold with anomalous energy ordering, being nonmonotonic in J. We propose a clock based on the 338.8 THz electric quadrupole transition between the ground (^{3}P_{2}) and first-excited (^{3}P_{0}) electronic states. We perform relativistic many-body calculations to determine relevant properties of this ion. The lifetime of the excited clock state is found to be several seconds, accommodating low statistical uncertainty with a single ion for practical averaging times. The differential static scalar polarizability is found to be small and negative, providing suppressed sensitivity to blackbody radiation while simultaneously allowing cancellation of Stark and excess micromotion shifts. With the exception of Hg^{+} and Yb^{+}, sensitivity to variation of the fine structure constant is greater than other optical clocks thus far demonstrated.

Development and acceptability of a video-based vaccine promotion tutorial for obstetric care providers.

A prenatal care provider's recommendation for maternal vaccines is one of the strongest predictors of vaccine acceptance during pregnancy. Aside from basic talking points, few resources exist to help obstetric care providers effectively navigate conversations with vaccine hesitant patients. This paper describes the development and acceptability of "VaxChat," an hour-long, evidence-based video tutorial aimed at improving obstetric care providers' ability to promote maternal vaccines. Between June and November 2017, 62 obstetric care providers registered to receive continuing medical education credit for viewing VaxChat. Of the post-tutorial responses received, over 90% said VaxChat increased their knowledge of what to say to vaccine hesitant patients, increased their confidence in addressing vaccinations with their pregnant patients, and will help them improve their practice culture regarding maternal vaccine promotion. Eighty percent intend to change how they approach vaccine conversations. These data suggest VaxChat may be a welcome complement to existing provider-to-patient talking points.

Systematic uncertainty due to background-gas collisions in trapped-ion optical clocks.

We describe a framework for calculating the frequency shift and uncertainty of trapped-ion optical atomic clocks caused by background-gas collisions, and apply this framework to an 27Al+ clock to enable a total fractional systematic uncertainty below 10-18. For this clock, with 38(19) nPa of room-temperature H2 background gas, we find that collisional heating generates a non-thermal distribution of motional states with a mean time-dilation shift of order 10-16 at the end of a 150 ms probe, which is not detected by sideband thermometry energy measurements. However, the contribution of collisional heating to the spectroscopy signal is highly suppressed and we calculate the BGC shift to be -0.6(2.4) × 10-19, where the shift is due to collisional heating time dilation and the uncertainty is dominated by the worst case ±π/2 bound used for collisional phase shift of the 27Al+ superposition state. We experimentally validate the framework and determine the background-gas pressure in situ using measurements of the rate of collisions that cause reordering of mixed-species ion pairs.

Sympathetic Ground State Cooling and Time-Dilation Shifts in an

We report on Raman sideband cooling of ^{25}Mg^{+} to sympathetically cool the secular modes of motion in a ^{25}Mg^{+}-^{27}Al^{+} two-ion pair to near the three-dimensional (3D) ground state. The evolution of the Fock-state distribution during the cooling process is studied using a rate-equation simulation, and various heating sources that limit the efficiency of 3D sideband cooling in our system are discussed. We characterize the residual energy and heating rates of all of the secular modes of motion and estimate a secular motion time-dilation shift of -(1.9±0.1)×10^{-18} for an ^{27}Al^{+} clock at a typical clock probe duration of 150 ms. This is a 50-fold reduction in the secular motion time-dilation shift uncertainty in comparison with previous ^{27}Al^{+} clocks.

Effectiveness of workplace interventions in the prevention of upper extremity musculoskeletal disorders and symptoms: an update of the evidence.

The burden of disabling musculoskeletal pain and injuries (musculoskeletal disorders, MSDs) arising from work-related causes in many workplaces remains substantial. There is little consensus on the most appropriate interventions for MSDs. Our objective was to update a systematic review of workplace-based interventions for preventing and managing upper extremity MSD (UEMSD). We followed a systematic review process developed by the Institute for Work & Health and an adapted best evidence synthesis. 6 electronic databases were searched (January 2008 until April 2013 inclusive) yielding 9909 non-duplicate references. 26 high-quality and medium-quality studies relevant to our research question were combined with 35 from the original review to synthesise the evidence on 30 different intervention categories. There was strong evidence for one intervention category, resistance training, leading to the recommendation: Implementing a workplace-based resistance training exercise programme can help prevent and manage UEMSD and symptoms. The synthesis also revealed moderate evidence for stretching programmes, mouse use feedback and forearm supports in preventing UEMSD or symptoms. There was also moderate evidence for no benefit for EMG biofeedback, job stress management training, and office workstation adjustment for UEMSD and symptoms. Messages are proposed for both these and other intervention categories.

Prevención de síntomas visuales y músculo-esqueléticos asociados al uso de ordenador en el trabajo / Workplace interventions to prevent musculoskeletal and visual symptoms and disorders among computer users: A systematic review

Antecedentes: La literatura científica sobre el efecto de las intervenciones en el puesto de trabajo, en la compensación de un defecto refractivo y en la conducta sobre los síntomas músculo-esqueléticos y visuales en los usuarios de ordenador, es amplia y heterogénea. Método: Se realizó una revisión sistemática de la literatura como la mejor síntesis de la evidencia para abordar la siguiente cuestión general: ¿Tienen las intervenciones en trabajadores de oficina que son usuarios de ordenador un efecto sobre la salud músculo-esquelética o visual? También se realizó una evaluación de intervenciones específicas. Resultados: La búsqueda inicial identificó 7.313 artículos que se redujeron a 31 estudios tras analizar contenido y calidad. En general, se observó un nivel mixto de evidencia para la pregunta general. Se observó una evidencia moderada de que: (1) la adaptación de los puestos de trabajo no tenía ningún efecto, (2) tampoco la realización de descansos y ejercicio y (3) utilizar dispositivos alternativos a los ratones convencionales sí tenía un efecto positivo. Para el resto de intervenciones se observó una evidencia del efecto mixta o insuficiente. Conclusión: Se encontraron pocos estudios de alta calidad que examinaran los efectos de las intervenciones en oficinas sobre los problemas musculo-esqueléticos y de la salud visual

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Effect of an arginine-containing nutritional supplement on pressure ulcer healing in community spinal patients.

OBJECTIVE: To determine whether or not the use of an arginine-containing nutritional supplement could result in significantly shorter pressure ulcer (PU) healing times in people with spinal cord injuries living in the community, compared with a comparative historical control group. METHOD: Eighteen spinal-cord-injured patients (all part of a hospital spinal outreach service) received 9 g of a commercial powdered arginine supplement per day until full PU healing occurred. Healing rates were compared against 17 historical control patients (as assessed by medical history audit). RESULTS: Baseline characteristics (age, gender, injury level and time) were similar between groups. Mean ulcer healing times were 10.5 +/- 1.3 weeks versus 21 +/- 3.7 weeks (p<0.05) in the intervention and control groups respectively. Comparison of healing rates in the intervention group against expected healing rates derived from the medical literature showed that intervention patients had a significantly shorter mean healing time (category 2 PU: 5.5+/-1.3 weeks versus 13.4 weeks; category 3 PU: 12.5 +/- 1.9 weeks versus 18.2 weeks; category 4 PU: 14.4 +/- 4.8 weeks versus 22.1 weeks). A diagnosis of diabetes did not significantly alter healing rates in either group. CONCLUSION: Results from this observational study show a promising benefit of arginine supplementation on PU healing for individuals with spinal cord injury living in the community.

Streptococcal protective antigens (Spa): a new family of type-specific proteins of group A streptococci.

Previous studies in our laboratory described a new group A streptococcal protective antigen (Spa) in type 18 streptococci that was distinct from the type 18 M protein. This study was undertaken to identify additional serotypes of group A streptococci that express Spa proteins. PCR techniques were used to identify and clone a new spa gene from type 36 streptococci. The 5' sequence of spa36 was highly variable compared to spa18, while the 3' sequence was conserved. Antisera against Spa36 opsonized type 36 streptococci but not type 18 streptococci, indicating that the opsonic Spa epitopes were type-specific. Antisera against the conserved carboxy-terminal half of Spa18 were used to identify Spa or Spa-like proteins expressed on the surface of 25 of 70 different serotypes of GAS. Spa proteins may represent a new family of type-specific surface antigens that function in concert with M proteins to elicit protective immune responses.

Consumer sensory evaluations of aging effects on beef quality.

The most important sensory attribute affecting consumer acceptability is tenderness, which is a complex trait. Aging is the practice of holding meat at low temperatures to improve tenderness. In order to assess consumer quality attributes, cattle were selected to represent a range of quality grades from Utility to Prime. Steaks from these cattle were aged in vacuum bags for 0, 7, or 14 d, cut, and cooked on open hearth grills to 70 degrees C. Sensory evaluation was completed by consumers (n= 522). Warner-Bratzler (WB) shear and various physical characteristics were also determined. Shear values decreased with aging time and tenderness increased. Consumers perceived the majority of change in tenderness occurred during the first 7 d of aging while change in WB shear was similar during the first 7 d and the second 7 d of aging. Aging had no effect (P > 0.05) on juiciness, flavor, pH, lipid content, or water content of steaks.

Duplication of the pale, soft, and exudative condition starting with normal postmortem pork.

The objective of the current study was to create an in vitro model that duplicated the development of PSE pork. Postrigor pork chops with various pH values and normal color were vacuum-packaged, and heated at approximately 42 degrees C for various times (0, 15, 30, 60, 120, or 240 min), or heated to temperatures that occur early postmortem (34, 37, 39, or 42 degrees C for 60 or 120 min) in a water bath. Chops were cooled and allowed to bloom, after which changes in Minolta and Hunter color values were assessed, and purge loss was determined. Warming postrigor pork with normal color and pH to early postmortem body temperature for various times successfully duplicated the characteristics of PSE pork. After 60 to 120 min at 42 degrees C or above, chops with pH < 5.8 lightened until L values were similar to those typical of PSE pork (Minolta L = 61.0). Change in chop color depended on length of time the samples were warmed, as well as on pH. Below 34 degrees C, temperature had no (P > or = 0.28) effect on color (Minolta L, a, b, and Hunter L*, a*, b*); however, at higher temperatures, color change depended on pH and warming time. A comparison of the time and temperature relationships for changes in lightness and purge suggested that the mechanisms of the two processes are not identical. The similarities in the dynamic range of color change, change in absolute color values, and time frame for changes in vitro and in vivo suggest similarity of the processes creating PSE in a carcass and in the in vitro model.

Overexpression of transcription factor AP-2alpha suppresses mammary gland growth and morphogenesis.

AP-2 transcription factors are key regulators of mouse embryonic development. Aberrant expression of these genes has also been linked to the progression of human breast cancer. Here, we have investigated the role of the AP-2 gene family in the postnatal maturation of the mouse mammary gland. Analysis of AP-2 RNA and protein levels demonstrates that these genes are expressed in the mammary glands of virgin and pregnant mice. Subsequently, AP-2 expression declines during lactation and then is reactivated during involution. The AP-2alpha and AP-2gamma proteins are localized in the ductal epithelium, as well as in the terminal end buds, suggesting that they may influence growth of the ductal network. We have tested this hypothesis by targeting AP-2alpha expression to the mouse mammary gland using the MMTV promoter. Our studies indicate that overexpression of AP-2alpha inhibits mammary gland growth and morphogenesis, and this coincides with a rise in PTHrP expression. Alveolar budding is severely curtailed in transgenic virgin mice, while lobuloalveolar development and functional differentiation are inhibited during pregnancy and lactation, respectively. Our studies strongly support a role for the AP-2 proteins in regulating the proliferation and differentiation of mammary gland epithelial cells in both mouse and human.