Real-Time TEM Imaging of the Formation of Crystalline Nanoscale Gaps

We present real-time transmission electron microscopy of nanogap formation by feedback controlled electromigration that reveals a remarkable degree of crystalline order. Crystal facets appear during feedback controlled electromigration indicating a layer-by-layer, highly reproducible electromigration process avoiding thermal runaway and melting. These measurements provide insight into the electromigration induced failure mechanism in sub-20 nm size interconnects, indicating that the current density at failure increases as the width decreases to approximately 1 nm

Injuries in Quidditch:A Prospective Study from a Complete UK Season

Background : Quidditch is a mixed-gender, full-contact sport founded in the USA in 2005, played worldwide by an estimated 25,000 players. It is one of the few mixed-gender full-contact sports, yet there remain few published studies regarding injury rates and patterns. A previous study suggested that the overall rate of injury in quidditch is in line with other contact sports, however raised concerns that female players were sustaining a higher rate of concussion when compared to male players. Purpose : To examine injury rates and injury patterns in UK quidditch athletes over the course of a single season. Study design: Prospective epidemiological study. Methods : Data were prospectively collected by professional first aid staff for the 2017-18 season spanning all major UK tournaments, involving 699 athletes. Anonymized player demographics were collected by an online survey. Time loss injury rates were measured per 1000 athletic exposures (AEs) and hours of play. Results: The overall time loss injury rate was 20.5 per 1000 hours or 8.0 per 1000 AEs. The combined rate of concussion was 7.3 per 1000 hours or 2.8 per 1000 AEs. There was no statistical difference between time loss injuries in males (20.9/1000 hours and 8.1/1000 AEs) and females (13.9/1000 hours and 5.4/1000 AEs) (p=0.30) and no statistical difference between concussion rates in males (n=7) and females (n=4) (p=0.60). Conclusions : Total time loss injury rates in quidditch appear to be comparable with other full-contact sports such as football. The rate of concussions for both males and females appear higher when compared to other contact sports. Level of evidence : 3Publisher PDFPeer reviewe

Scaling of the B and D meson spectrum in lattice QCD

We give results for the $B$ and the $D$ meson spectrum using NRQCD on the lattice in the quenched approximation. The masses of radially and orbitally excited states are calculated as well as $S$-wave hyperfine and $P$-wave fine structure. Radially excited $P$-states are observed for the first time. Radial and orbital excitation energies match well to experiment, as does the strange-non-strange $S$-wave splitting. We compare the light and heavy quark mass dependence of various splittings to experiment. Our $B$-results cover a range in lattice spacings of more than a factor of two. Our $D$-results are from a single lattice spacing and we compare them to numbers in the literature from finer lattices using other methods. We see no significant dependence of physical results on the lattice spacing. PACS: 11.15.Ha 12.38.Gc 14.40.Lb 14.40.NdComment: 78 pages, 29 tables, 30 figures Revised version. Minor corrections to spelling and wordin

Heavy Quarkonium and nonperturbative corrections

We analyse the possible existence of non-perturbative contributions in heavy $\bar Q Q$ systems ($\bar Q$ and $Q$ need not have the same flavour) which cannot be expressed in terms of local condensates. Starting from QCD, with well defined approximations and splitting properly the fields into large and small momentum components, we derive an effective lagrangian where hard gluons (in the non-relativistic aproximation) have been integrated out. The large momentum contributions (which are dominant) are calculated using Coulomb type states. Besides the usual condensate corrections, we see the possibility of new non-perturbative contributions. We parametrize them in terms of two low momentum correlators with Coulomb bound state energy insertions $E_n$. We realize that the Heavy Quark Effective lagrangian can be used in these correlators. We calculate the corrections that they give rise to in the decay constant, the bound state energy and the matrix elements of bilinear currents at zero recoil. We study the cut-off dependence of the new contributions and we see that it matches perfectly with that of the large momentum contributions. We consider two situations in detail: i) $E_n>> \Lambda_{QCD}$ ($M_Q \rightarrow \infty$) and ii) $E_n << \Lambda_{QCD}$, and briefly discuss the expected size of the new contributions in $\Upsilon$ , $J/\Psi$ and $B_{c}^{\ast}$ systems.Comment: 28 pages, LaTeX. Minor changes, some comments and numerical results added. To be published in Phys. Rev.

Improved Nonrelativistic QCD for Heavy Quark Physics

We construct an improved version of nonrelativistic QCD for use in lattice simulations of heavy quark physics, with the goal of reducing systematic errors from all sources to below 10\%. We develop power counting rules to assess the importance of the various operators in the action and compute all leading order corrections required by relativity and finite lattice spacing. We discuss radiative corrections to tree level coupling constants, presenting a procedure that effectively resums the largest such corrections to all orders in perturbation theory. Finally, we comment on the size of nonperturbative contributions to the coupling constants.Comment: 40 pages, 2 figures (not included), in LaTe

Renormalization-Scale-Invariant PQCD Predictions for R_e+e- and the Bjorken Sum Rule at Next-to-Leading Order

We discuss application of the physical QCD effective charge $\alpha_V$, defined via the heavy-quark potential, in perturbative calculations at next-to-leading order. When coupled with the Brodsky-Lepage-Mackenzie prescription for fixing the renormalization scales, the resulting series are automatically and naturally scale and scheme independent, and represent unambiguous predictions of perturbative QCD. We consider in detail such commensurate scale relations for the $e^+e^-$ annihilation ratio $R_{e^+e^-}$ and the Bjorken sum rule. In both cases the improved predictions are in excellent agreement with experiment.Comment: 13 Latex pages with 5 figures; to be published in Physical Review

A massive cluster of Red Supergiants at the base of the Scutum-Crux arm

We report on the unprecedented Red Supergiant (RSG) population of a massive young cluster, located at the base of the Scutum-Crux Galactic arm. We identify candidate cluster RSGs based on {\it 2MASS} photometry and medium resolution spectroscopy. With follow-up high-resolution spectroscopy, we use CO-bandhead equivalent width and high-precision radial velocity measurements to identify a core grouping of 26 physically-associated RSGs -- the largest such cluster known to-date. Using the stars' velocity dispersion, and their inferred luminosities in conjuction with evolutionary models, we argue that the cluster has an initial mass of $\sim$40,000\msun, and is therefore among the most massive in the galaxy. Further, the cluster is only a few hundred parsecs away from the cluster of 14 RSGs recently reported by Figer et al (2006). These two RSG clusters represent 20% of all known RSGs in the Galaxy, and now offer the unique opportunity to study the pre-supernova evolution of massive stars, and the Blue- to Red-Supergiant ratio at uniform metallicity. We use GLIMPSE, MIPSGAL and MAGPIS survey data to identify several objects in the field of the larger cluster which seem to be indicative of recent region-wide starburst activity at the point where the Scutum-Crux arm intercepts the Galactic bulge. Future abundance studies of these clusters will therefore permit the study of the chemical evolution and metallicity gradient of the Galaxy in the region where the disk meets the bulge.Comment: 49 pages, 22 figures. Accepted for publication in ApJ. Version with hi-res figures can be found at http://www.cis.rit.edu/~bxdpci/RSGC2.pd

The nutritional status of children with cystic fibrosis

The importance of nutritional intervention for children with cystic fibrosis (CF) is well recognised. It would be expected that the increase in knowledge over the past decade would be reflected in improvements in nutritional status for the CF paediatric population. The aim of the present paper was to evaluate the nutritional status of children with CF, cross-sectionally and longitudinally. Body cell mass adjusted for gender and size (BCM/Ht(p)) was measured in sixty-four children with CF to represent nutritional status and expressed as a Z-score. The cross-sectional results showed a mean BCM/Ht(p) Z-score of 0.54 (sd 1.21), with males having a slightly higher Z-score than females but with a larger variation. At the initial measurement, only one female and one male were considered sub-optimally nourished. The longitudinal analysis after 2 years showed that the mean population had a significantly decreased BCM/Ht(p) Z-score; however, when each gender was analysed separately, this decrease was significant only in the males. At the final measurement, only two females and three males were considered sub-optimally nourished. It is evident from our results that children with CF are well nourished, with only a small percentage considered malnourished. It appears that nutritional status decreases with age, with this decline being more evident in males. These results signify that although children with CF are better nourished with current treatment support, intervention needs to continue throughout a CF patient's life to counteract the changes that occur with age

Effects of the COVID-19 lockdown on orthopaedic trauma:a multicentre study across Scotland

Aims: The UK government declared a national lockdown on 23 March 2020 to reduce transmission of COVID-19. This study aims to identify the effect of lockdown on the rates, types, mechanisms, and mortality of musculoskeletal trauma across Scotland.Methods: Data for all musculoskeletal trauma requiring operative treatment were collected prospectively from five key orthopaedic units across Scotland during lockdown (23 March 2020 to 28 May 2020). This was compared with data for the same timeframe in 2019 and 2018. Data collected included all cases requiring surgery, injury type, mechanism of injury, and inpatient mortality.Results: A total of 1,315 patients received operative treatment from 23 March 2020 to 28 May 2020 compared with 1,791 in 2019 and 1,719 in 2018. The numbers of all injury types decreased, but the relative frequency of hip fractures increased (36.3% in 2020 vs 30.2% in 2019, p &lt; 0.0001 and 30.7% in 2018, p &lt; 0.0001). Significant increases were seen in the proportion of DIY-related injuries (3.1% in 2020 vs 1.7% in 2019, p = 0.012 and 1.6% in 2018, p &lt; 0.005) and injuries caused by falls (65.6% in 2020 vs 62.6% in 2019, p = 0.082 and 61.9% in 2018, p = 0.047). Significant decreases were seen in the proportion of road traffic collisions (2.6% in 2020 vs 5.4% in 2019, p &lt; 0.0001 and 4.2% in 2018, p = 0.016), occupational injuries (1.8% in 2020 vs 3.0% in 2019, p = 0.025 and 2.3% in 2018, p = 0.012) and infections (6.8% in 2020 vs 7.8% in 2019, p = 0.268 and 10.3% in 2018, p &lt; 0.012). Cycling injuries increased (78 in 2020 vs 64 in 2019 vs 42 in 2018). A significant increase in the proportion of self-harm injuries was seen (1.7% in 2020 vs 1.1% in 2019, p = 0.185 and 0.5% in 2018, p &lt; 0.0001). Mortality of trauma patients was significantly higher in 2020 (5.0%) than in 2019 (2.8%, p = 0.002) and 2018 (1.8%, p &lt; 0.0001).Conclusion: The UK COVID-19 lockdown has resulted in a marked reduction in musculoskeletal trauma patients undergoing surgery in Scotland. There have been significant changes in types and mechanisms of injury and, concerningly, mortality of trauma patients has risen significantly.</p