Exploring the S-Matrix of Massless Particles

We use the recently proposed generalised on-shell representation for scattering amplitudes and a consistency test to explore the space of tree-level consistent couplings in four-dimensional Minkowski spacetime. The extension of the constructible notion implied by the generalised on-shell representation, i.e. the possibility to reconstruct at tree level all the scattering amplitudes from the three-particle ones, together with the imposition of the consistency conditions at four-particle level, allow to rediscover all the known theories and their algebra structure, if any. Interestingly, this analysis seems to leave room for high-spin couplings, provided that at least the requirement of locality is weakened. We do not claim to have found tree-level consistent high-spin theories, but rather that our methods show signatures of them and very likely, with a suitable modification, they can be a good framework to perform a systematic search.Comment: 44 pages, 1 figur

On the Abundance of Circumbinary Planets

We present here the first observationally based determination of the rate of occurrence of circumbinary planets. This is derived from the publicly available Kepler data, using an automated search algorithm and debiasing process to produce occurrence rates implied by the seven systems already known. These rates depend critically on the planetary inclination distribution: if circumbinary planets are preferentially coplanar with their host binaries, as has been suggested, then the rate of occurrence of planets with $R_p>6R_\oplus$ orbiting with $P_p<300$\ d is $10.0 ^{+18}_{-6.5}$\% (95\% confidence limits), higher than but consistent with single star rates. If on the other hand the underlying planetary inclination distribution is isotropic, then this occurrence rate rises dramatically, to give a lower limit of 47\%. This implies that formation and subsequent dynamical evolution in circumbinary disks must either lead to largely coplanar planets, or proceed with significantly greater ease than in circumstellar disks. As a result of this investigation we also show that giant planets (${>}10R_\oplus$) are significantly less common in circumbinary orbits than their smaller siblings, and confirm that the proposed shortfall of circumbinary planets orbiting the shorter period binaries in the Kepler sample is a real effect.Comment: Accepted for publication in MNRAS (1st August 2014). 12 pages. Update to match final version, including clarifications and new figures. Results are unchange

Implementation of a Large System-Wide Hepatitis C Virus Screening and Linkage to Care Program for Baby Boomers.

BackgroundWe implemented and evaluated a large health system-wide hepatitis C virus (HCV) screening and linkage to care program for persons born between 1945 and 1965 ("baby boomers").MethodsAn electronic health record (EHR) clinical decision support (CDS) tool for HCV screening for baby boomers was introduced in August 2015 for patients seen in the outpatient University of California, Los Angeles healthcare system setting. An HCV care coordinator was introduced in January 2016 to facilitate linkage to HCV care. We compared HCV testing in the year prior (August 2014-July 2015) to the year after (August 2015-July 2016) implementation of the CDS tool. Among patients with reactive HCV antibody testing, we compared outcomes related to the care cascade including HCV ribonucleic acid (RNA) testing, HCV RNA positivity, and linkage to HCV specialty care.ResultsDuring the study period, 19606 participants were screened for HCV antibody. Hepatitis C virus antibody screening increased 145% (from 5676 patients tested to 13930 tested) after introduction of the CDS intervention. Screening increased across all demographic groups including age, sex, and race/ethnicity, with the greatest increases among those in the older age groups. The addition of an HCV care coordinator increased follow-up HCV RNA testing for HCV antibody positive patients from 83% to 95%. Ninety-four percent of HCV RNA positive patients were linked to care postimplementation.ConclusionsIntroduction of an EHR CDS tool and care coordination markedly increased the number of baby boomers screened for HCV, rates of follow-up HCV RNA testing, and linkage to specialty HCV care for patients with chronic HCV infection

Mechanical vaccum pumps

This presentation gives an overview of the technology of contemporary primary and secondary mechanical vacuum pumps. For reference a brief history of vacuum and a summary of important and basic vacuum concepts are first presented

Isotropic-medium three-dimensional cloaks for acoustic and electromagnetic waves

We propose a generalization of the two-dimensional eikonal-limit cloak derived from a conformal transformation to three dimensions. The proposed cloak is a spherical shell composed of only isotropic media; it operates in the transmission mode and requires no mirror or ground plane. Unlike the well-known omnidirectional spherical cloaks, it may reduce visibility of an arbitrary object only for a very limited range of observation angles. In the short-wavelength limit, this cloaking structure restores not only the trajectories of incident rays, but also their phase, which is a necessary ingredient to complete invisibility. Both scalar-wave (acoustic) and transverse vector-wave (electromagnetic) versions are presented.Comment: 17 pages, 12 figure

Feasibility of training practice nurses to deliver a psychosocial intervention within a collaborative care framework for people with depression and long-term conditions

Background Practice nurses (PNs) deliver much of the chronic disease management in primary care and have been highlighted as appropriately placed within the service to manage patients with long-term physical conditions (LTCs) and co-morbid depression. This nested qualitative evaluation within a service development pilot provided the opportunity to examine the acceptability of a Brief Behavioural Activation (BBA) intervention within a collaborative care framework. Barriers and facilitators to engaging with the intervention from the patient and clinician perspective will be used to guide future service development and research. Methods The study was conducted across 8 practices in one Primary Care Trust 1 in England. Through purposive sampling professionals (n = 10) taking part in the intervention (nurses, GPs and a mental health gateway worker) and patients (n = 4) receiving the intervention participated in semi-structured qualitative interviews. Analysis utilised the four Normalisation Process Theory (NPT) concepts of coherence, cognitive participation, collective action and reflexive monitoring to explore the how this intervention could be implemented in practice. Results Awareness of depression and the stigma associated with the label of depression meant that, from a patient perspective a PN being available to ‘listen’ was perceived as valuable. Competing practice priorities, perceived lack of time and resources, and lack of engagement by the whole practice team were considered the greatest barriers to the implementation of this intervention in routine primary care. Conclusion Lack of understanding of, participation in, and support from the whole practice team in the collaborative care model exacerbated the pressures perceived by PNs. The need for formal supervision of PNs to enable them to undertake the role of case manager for patients with depression and long-term conditions is emphasised

Evaluation of the efficacy and safety of high dose short duration enrofloxacin treatment regimen for uncomplicated urinary tract infections in dogs.

BackgroundUncomplicated urinary tract infections (UTI) in dogs usually are treated with antimicrobial drugs for 10-14 days. Shorter duration antimicrobial regimens have been evaluated in human patients.HypothesisA high dose short duration (HDSD) enrofloxacin protocol administered to dogs with uncomplicated UTI will not be inferior to a 14-day treatment regimen with amoxicillin-clavulanic acid.AnimalsClient-owned adult, otherwise healthy dogs with aerobic bacterial urine culture yielding ≥ 10(3) CFU/mL of bacteria after cystocentesis.MethodsProspective, multicenter, controlled, randomized blinded clinical trial. Enrolled dogs were randomized to group 1 (enrofloxacin 18-20 mg/kg PO q24h for 3 days) or group 2 (amoxicillin-clavulanic acid 13.75-25 mg/kg PO q12h for 14 days). Urine cultures were obtained at days 0, 10, and 21. Microbiologic and clinical cure rates were evaluated 7 days after antimicrobial treatment was discontinued. Lower urinary tract signs and adverse events also were recorded.ResultsThere were 35 dogs in group 1 and 33 in group 2. The microbiologic cure rate was 77.1 and 81.2% for groups 1 and 2, respectively. The clinical cure rate was 88.6 and 87.9% for groups 1 and 2, respectively. Cure rates between groups did not differ according to the selected margin of noninferiority.Conclusions and clinical importanceHDSD enrofloxacin treatment was not inferior to a conventional amoxicillin-clavulanic acid protocol for the treatment of uncomplicated bacterial UTI in dogs. Further research is warranted to determine if this protocol will positively impact owner compliance and decrease the emergence of antimicrobial resistance

Frozen light in photonic crystals with degenerate band edge

Consider a plane monochromatic wave incident on a semi-infinite periodic structure. What happens if the normal component of the transmitted wave group velocity vanishes? At first sight, zero normal component of the transmitted wave group velocity simply implies total reflection of the incident wave. But we demonstrate that total reflection is not the only possible outcome. Instead, the transmitted wave can appear in the form of a frozen mode with very large diverging amplitude and either zero, or purely tangential energy flux. The field amplitude in the transmitted wave can exceed that of the incident wave by several orders of magnitude. There are two qualitatively different kinds of frozen mode regime. The first one is associated with a stationary inflection point of electromagnetic dispersion relation. This phenomenon has been analyzed in our previous publications. Now, our focus is on the frozen mode regime related to a degenerate photonic band edge. An advantage of this new phenomenon is that it can occur in much simpler periodic structures. This spectacular effect is extremely sensitive to the frequency and direction of propagation of the incident plane wave. These features can be very attractive in a variety practical applications, such as higher harmonic generation and wave mixing, light amplification and lasing, highly efficient superprizms, etc