On the Energy-Momentum Tensor of the Scalar Field in Scalar--Tensor Theories of Gravity

We study the dynamical description of gravity, the appropriate definition of the scalar field energy-momentum tensor, and the interrelation between them in scalar-tensor theories of gravity. We show that the quantity which one would naively identify as the energy-momentum tensor of the scalar field is not appropriate because it is spoiled by a part of the dynamical description of gravity. A new connection can be defined in terms of which the full dynamical description of gravity is explicit, and the correct scalar field energy-momentum tensor can be immediately identified. Certain inequalities must be imposed on the two free functions (the coupling function and the potential) that define a particular scalar-tensor theory, to ensure that the scalar field energy density never becomes negative. The correct dynamical description leads naturally to the Einstein frame formulation of scalar-tensor gravity which is also studied in detail.Comment: Submitted to Phys. Rev D15, 10 pages. Uses ReVTeX macro

Clinical Measures of Bulbar Dysfunction in ALS

Bulbar impairment represents a hallmark feature of Amyotrophic Lateral Sclerosis (ALS) that significantly impacts survival and quality of life. Speech and swallowing dysfunction are key contributors to the clinical heterogeneity of ALS and require well-timed and carefully coordinated interventions. The accurate clinical, radiological and electrophysiological assessment of bulbar dysfunction in ALS is one of the most multidisciplinary aspects of ALS care, requiring expert input from speech-language pathologists (SLPs), neurologists, otolaryngologists, augmentative alternative communication (AAC) specialists, dieticians, and electrophysiologists—each with their own evaluation strategies and assessment tools. The need to systematically evaluate the comparative advantages and drawbacks of various bulbar assessment instruments and to develop integrated assessment protocols is increasingly recognized. In this review, we provide a comprehensive appraisal of the most commonly utilized clinical tools for assessing and monitoring bulbar dysfunction in ALS based on the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) evaluation framework. Despite a plethora of assessment tools, considerable geographical differences exist in bulbar assessment practices and individual instruments exhibit considerable limitations. The gaps identified in the literature offer unique opportunities for the optimization of existing and development of new tools both for clinical and research applications. The multicenter validation and standardization of these instruments will be essential for guideline development and best practice recommendations

Axion-Dilaton Cosmology and Dark Energy

We discuss a class of flat FRW cosmological models based on D=4 axion-dilaton gravity universally coupled to cosmological background fluids. In particular, we investigate the possibility of recurrent acceleration, which was recently shown to be generically realized in a wide class of axion-dilaton models, but in absence of cosmological background fluids. We observe that, once we impose the existence of radiation -and matter- dominated earlier stages of cosmic evolution, the axion-dilaton dynamics is altered significantly with respect to the case of pure axion-dilaton gravity. During the matter dominated epoch the scalar fields remain either frozen, due to the large expansion rate, or enter a cosmological scaling regime. In both cases, oscillations of the effective equation of state around the acceleration boundary value are impossible. Models which enter an oscillatory stage in the low redshift regime, on the other hand, are disfavored by observations. We also comment on the viability of the axion-dilaton system as a candidate for dynamical dark energy. In a certain subclass of models, an intermediate scaling regime is succeeded by eternal acceleration. We also briefly discuss the issue of dependence on initial conditions.Comment: 28 pages, 11 figure

Three Week Hypergravity Training Intervention Decreases Ground Contact Time During Repeated Jumping and Improves Sprinting and Shuttle Running Performance

International Journal of Exercise Science 9(2): 149-158, 2016. This study examined the effects of a non-traditional training method, hypergravity training (HT), on anaerobic performance. Highly active men (n = 9) completed a 3 week HT protocol in which weighted vests were worn 8 h/day, 4+ days/week separate from training. Vest loads were 11.2 ± 0.6% of body mass during week one, and increased to 13.2 ± 0.7% (week 2), and 16.1 ± 0.4% (week 3). Performance testing included power clean 1-RM (PC), counter movement jumps, 4 continuous jumps, 36.6 m sprints (SP), a 137.2 m short shuttle run (SSR), and a 274.3 m long shuttle run (LSR). A 3 week non-hypergravity training period (NHT) proceeded HT. Baseline SP improved from 4.69 ± 0.29 s to 4.58 ± 0.22 s post-treatment, and regressed after NHT (4.69 ± 0.24 s) (p = 0.006, ES = 1.80). Improvements in SSR (p = 0.012, ES = 1.71) occurred from baseline (26.7 ± 1.5 s) to post-treatment (26.2 ± 1.4 s), followed by a return to near-baseline values (26.9 ± 1.8 s). Jumping tasks displayed similar trends, but no statistical differences and modest effect sizes (0.51 - 0.62) were found except for improved ground contact time during repeated jumps post-HT (ES = 2.26). PC and LSR performances did not improve. Three weeks of HT significantly enhanced short running task performances and decreased ground contact time between 4 continuous jumps. HT may be incorporated into training programs prior to key points in an athletic season without hindering the quality of regular training session activities

Performance and perceptual responses of collegiate female soccer players to a practical external and internal cooling protocol

International Journal of Exercise Science 8(4): 331-340, 2015. This study examined practical pre- and mid practice cooling interventions on running performance, perceived exertion (RPE), and thermal sensation (TS) during soccer. During two formal pre-season practices female, NCAA Division II soccer players participated in three, 15 min scrimmage bouts followed by a 4th 10 min bout. Following the 1st, 2nd, and 3rd bouts, 8 field position players completed competitive sets of two, 30 yard sprints against other team members with time recorded between 5 and 30 yards. After the 4th bout, players completed an indoor shuttle running beep test (BT). In the treatment group (COOL) ice towels (IT) were applied to the head and neck regions and draped across both legs for 10 min following a standardized warm-up and for 10 min during a 15 min break between the 2nd and 3rd scrimmage sessions. Sport beverage slurries (350 mL; -0.3 °C, ~6% carbohydrate) were also served during IT cooling for COOL; while the control (CON) received no IT and drank the same ,uncooled sport beverage. No main effect was found for sprint performance (COOL = 3.55 ± 0.16 s; CON = 3.51 ± 0.07 s; P = 0.51) or numbers of reps completed in the BT (COOL = 17.6 ± 5.6; CON = 17.3 ± 6.0; P = 0.88). RPE did not differ following any performance test, but TS was lower following the 3rd sprint bout (P = 0.04) and the BT (P = 0.005) for COOL. COOL promoted lower TS, but had no effect on performance

Nucleosynthesis Constraints on Scalar-Tensor Theories of Gravity

We study the cosmological evolution of massless single-field scalar-tensor theories of gravitation from the time before the onset of $e^+e^-$ annihilation and nucleosynthesis up to the present. The cosmological evolution together with the observational bounds on the abundances of the lightest elements (those mostly produced in the early universe) place constraints on the coefficients of the Taylor series expansion of $a(\phi)$, which specifies the coupling of the scalar field to matter and is the only free function in the theory. In the case when $a(\phi)$ has a minimum (i.e., when the theory evolves towards general relativity) these constraints translate into a stronger limit on the Post-Newtonian parameters $\gamma$ and $\beta$ than any other observational test. Moreover, our bounds imply that, even at the epoch of annihilation and nucleosynthesis, the evolution of the universe must be very close to that predicted by general relativity if we do not want to over- or underproduce $^{4}$He. Thus the amount of scalar field contribution to gravity is very small even at such an early epoch.Comment: 15 pages, 2 figures, ReVTeX 3.1, submitted to Phys. Rev. D1

Adenovirus 5 recovery using nanofiber ion‐exchange adsorbents

This is an accepted manuscript of an article published by Wiley in Biotechnology and Bioengineering on 28/03/2019, available online: https://doi.org/10.1002/bit.26972 The accepted version of the publication may differ from the final published version.Viral vectors such as adenovirus have successful applications in vaccines and gene therapy but the manufacture of the high‐quality virus remains a challenge. It is desirable to use the adsorption‐based chromatographic separations that so effectively underpin the therapeutic protein manufacture. However fundamental differences in the size and stability of this class of product mean it is necessary to revisit the design of sorbent's morphology and surface chemistry. In this study, the behaviour of a cellulose nanofiber ion‐exchange sorbent derivatised with quaternary amine ligands at defined densities is characterised to address this. This material was selected as it has a large accessible surface area for viral particles and rapid process times. Initially, the impact of surface chemistry on infective product recovery using low (440 µmol/g), medium (750 µmol/g), and high (1029 µmol/g) ligand densities is studied. At higher densities product stability is reduced, this effect increased with prolonged adsorption durations of 24 min with just ~10% loss at low ligand density versus ~50% at high. This could be mitigated by using a high flow rate to reduce the cycle time to ~1 min. Next, the impact of ligand density on the separation's resolution was evaluated. Key to understanding virus quality is the virus particle: infectious virus particle ratio. It was found this parameter could be manipulated using ligand density and elution strategy. Together this provides a basis for viral vector separations that allows for their typically low titres and labile nature by using high liquid velocity to minimise both load and on‐column times while separating key product and process‐related impurities.This study was supported by the UK Engineering and Physical Sciences Research Council (EPSRC) grant EP/L01520X/1, and Puridify (now part of GE Healthcare), in conjunction with grant EP/N013395/1.Published versio

Genetic disruption of oncogenic Kras sensitizes lung cancer cells to Fas receptor-mediated apoptosis

Genetic lesions that activate KRAS account for approximately 30% of the 1.6 million annual cases of lung cancer. Despite clinical need, KRAS is still undruggable using traditional small-molecule drugs/inhibitors. When oncogenic Kras is suppressed by RNA interference, tumors initially regress but eventually recur and proliferate despite suppression of Kras Here, we show that tumor cells can survive knockout of oncogenic Kras, indicating the existence of Kras-independent survival pathways. Thus, even if clinical KRAS inhibitors were available, resistance would remain an obstacle to treatment. Kras-independent cancer cells exhibit decreased colony formation in vitro but retain the ability to form tumors in mice. Comparing the transcriptomes of oncogenic Kras cells and Kras knockout cells, we identified 603 genes that were specifically up-regulated in Kras knockout cells, including the Fas gene, which encodes a cell surface death receptor involved in physiological regulation of apoptosis. Antibodies recognizing Fas receptor efficiently induced apoptosis of Kras knockout cells but not oncogenic Kras-expressing cells. Increased Fas expression in Kras knockout cells was attributed to decreased association of repressive epigenetic marks at the Fas promoter. Concordant with this observation, treating oncogenic Kras cells with histone deacetylase inhibitor and Fas-activating antibody efficiently induced apoptosis, thus bypassing the need to inhibit Kras. Our results suggest that activation of Fas could be exploited as an Achilles\u27 heel in tumors initiated by oncogenic Kras

On the variation of the gauge couplings during inflation

It is shown that the evolution of the (Abelian) gauge coupling during an inflationary phase of de Sitter type drives the growth of the two-point function of the magnetic inhomogeneities. After examining the constraints on the variation of the gauge coupling arising in a standard model of inflationary and post-inflationary evolution, magnetohydrodynamical equations are generalized to the case of time evolving gauge coupling. It is argued that large scale magnetic fields can be copiously generated. Other possible implications of the model are outlined.Comment: 5 pages in RevTex style, one figur