1,637 research outputs found
Observable Effects of Scalar Fields and Varying Constants
We show by using the method of matched asymptotic expansions that a
sufficient condition can be derived which determines when a local experiment
will detect the cosmological variation of a scalar field which is driving the
spacetime variation of a supposed constant of Nature. We extend our earlier
analyses of this problem by including the possibility that the local region is
undergoing collapse inside a virialised structure, like a galaxy or galaxy
cluster. We show by direct calculation that the sufficient condition is met to
high precision in our own local region and we can therefore legitimately use
local observations to place constraints upon the variation of "constants" of
Nature on cosmological scales.Comment: Invited Festscrift Articl
Physiotherapy for Patients with Sciatica Awaiting Lumbar Micro-discectomy Surgery: A Nested, Qualitative Study of Patients' Views and Experiences
Background and Purpose
Sciatica is a common clinical condition that can be extremely painful, disabling and lifeâchanging. Whether conservative or surgical treatment for sciatica secondary to an intervertebral disc prolapse is most effective is still much debated. An important component of conservative treatment is physiotherapy, which aims to promote physical and psychological health for the patient, whilst resorption of the disc takes place. This paper reports a qualitative study of patients' views and experiences of a bespoke physiotherapy intervention for the treatment of sciatica.
Methods
A qualitative study nested within a pilot randomized controlled trial of bespoke physiotherapy for the treatment of patients with sciatica awaiting lumbar microdiscectomy surgery. Patients randomized to receive bespoke physiotherapy in the intervention arm of the trial were invited to take part in semiâstructured interviews. Twentyâone inâdepth, semiâstructured interviews took place. All interviews were recorded, fully transcribed and thematically analysed.
Results
Most patients in the sample found the physiotherapy valuable, appreciating the individual nature of the approach, the exercises to reduce pain and discomfort, techniques for improving functional spinal movement, walking and dynamic posture, and manual therapy and cardiovascular exercise. A small number did not find the physiotherapy of benefit. Sixteen patients in the sample went on to proceed with surgery, but most of these found value in having had the physiotherapy first.
Discussion
Many patients with sciatica appreciate the value of physiotherapy prior to surgery. Future research should examine patients' experiences of bespoke physiotherapy delivered within primary care
Reduced differential transform method for solving (1Â +Â n) â Dimensional Burgers' equation
AbstractThis paper discusses a recently developed semi-analytic technique so called the reduced differential transform method (RDTM) for solving the (1Â +Â n) â dimensional Burgers' equation. The method considers the use of the appropriate initial or boundary conditions and finds the solution without any discretization, transformation, or restrictive assumptions. Four numerical examples are provided in order to validate the efficiency and reliability of the method and furthermore to compare its computational effectiveness with other analytical methods available in the literature
Interactions of inert confiners with explosives
The deformation of an inert confiner by a steady detonation wave in an
adjacent explosive is investigated for cases where the confiner is suciently strong
(or the explosive suciently weak) such that the overall change in the sound speed
of the inert is small. A coupling condition which relates the pressure to the deflection
angle along the explosive-inert interface is determined. This includes its dependence
on the thickness of the inert, for cases where the initial sound speed of the inert
is less than or greater than the detonation speed in the explosive (supersonic and
subsonic inert
ows, respectively). The deformation of the inert is then solved by
prescribing the pressure along the interface. In the supersonic case, the detonation
drives a shock into the inert, subsequent to which the
ow in the inert consists
of alternating regions of compression and tension. In this case reverberations or
`ringing' occurs along both the deflected interface and outer edge of the inert. For
the subsonic case, the
flow in the interior of the inert is smooth and shockless.
The detonation in the explosive initially defl
ects the smooth interface towards the
explosive. For sufficiently thick inerts in such cases, it appears that the deflection
of the confiner would either drive the detonation speed in the explosive up to the
sound speed of the inert or drive a precursor wave ahead of the detonation in the
explosive. Transonic cases, where the inert sound speed is close to the detonation
speed, are also considered. It is shown that the confinement affect of the inert on
the detonation is enhanced as sonic conditions are approached from either side
Using GIS to integrate old and new archaeological data from Stone Age deposits in Karonga, Malawi
The Karonga District of northern Malawi has an extensive Stone Age archaeological record, primarily represented by stone artefacts that occur in both superficial and buried contexts. Work conducted in the 1960s provided initial documentation of this record. Some of this was presented in summary form in a small number of publications. However, most data were restricted to unpublished field notes, maps, and other static or largely inaccessible formats. GIS has been an essential tool for bringing together these diverse datasets in a digital format to facilitate integration of new research and promote reinvestigation of old sites. Examples from both the regional and site scale demonstrate how old data have been combined with recent survey and excavation data to document, analyse, interpret, and archive current knowledge about the rich Stone Age record of northern Malawi. A significant result from this approach has been the suggested reinterpretation of the Mwangandaâs Village Site
New Travelling Wave Solutions of Two Nonlinear Physical Models by Using a Modified Tanh-Coth Method
In this work, a modified tanh â coth method is used to derive travelling wave solutions for (2 + 1)-dimensional Zakharov-Kuznetsov (ZK) equation and (3 + 1)-dimensional Burgers equation. A new variable is used to solve these equations and established new travelling wave solutions. </jats:p
The relationship between fibrogenic TGFÎČ1 signaling in the joint and cartilage degradation in post-injury osteoarthritis
SummaryObjectiveTo review the literature on modulation of chondrocyte activities in the osteoarthritic joint, and to discuss these changes in relation to established hard and soft tissue repair paradigms, with an emphasis on transforming growth factor beta (TGFÎČ1)-mediated signaling which can promote either a chondrogenic or fibrogenic phenotype.MethodsPapers addressing the close relationship between repair in general, and the specific post-injury response of joint tissues are summarized. Different interpretations of the role of TGFÎČ1 in the emergence of an âosteoarthriticâ chondrocyte are compared and the phenotypic plasticity of âreparativeâ progenitor cells is examined. Lastly, emerging data on a central role for A-Disintegrin-And-Metalloproteinase-with-Thrombospondin-like-Sequences-5 (ADAMTS5) activity in modulating TGFÎČ1 signaling through activin receptor-like kinase 1 (ALK1) and activin receptor-like kinase 5 (ALK5) pathways is discussed.ResultsThe review illustrates how a transition from ALK5-mediated fibrogenic signaling to ALK1-mediated chondrogenic signaling in joint cells represents the critical transition from a non-reparative to a reparative cell phenotype. Data from cell and in vivo studies illustrates the mechanism by which ablation of ADAMTS5 activity allows the transition to reparative chondrogenesis. Multiple large gene expression studies of normal and osteoarthritis (OA) human cartilages (CAs) also support an important role for TGFÎČ1-mediated pro-fibrogenic activities during disease progression.ConclusionsWe conclude that progressive articular CA damage in post-injury OA results primarily from biomechanical, cell biologic and mediator changes that promote a fibroblastic phenotype in joint cells. Since ADAMTS5 and TGFÎČ1 appear to control this process, agents which interfere with their activities may not only enhance endogenous CA repair in vivo, but also improve the properties of tissue-engineered CA for implantation
Advances in the proposed electromagnetic zero-point field theory of inertia
A NASA-funded research effort has been underway at the Lockheed Martin
Advanced Technology Center in Palo Alto and at California State University in
Long Beach to develop and test a recently published theory that Newton's
equation of motion can be derived from Maxwell's equations of electrodynamics
as applied to the zero-point field (ZPF) of the quantum vacuum. In this
ZPF-inertia theory, mass is postulated to be not an intrinsic property of
matter but rather a kind of electromagnetic drag force that proves to be
acceleration dependent by virtue of the spectral characteristics of the ZPF.
The theory proposes that interactions between the ZPF and matter take place at
the level of quarks and electrons, hence would account for the mass of a
composite neutral particle such as the neutron. An effort to generalize the
exploratory study of Haisch, Rueda and Puthoff (1994) into a proper
relativistic formulation has been successful. Moreover the principle of
equivalence implies that in this view gravitation would also be electromagnetic
in origin along the lines proposed by Sakharov (1968). With regard to exotic
propulsion we can definitively rule out one speculatively hypothesized
mechanism: matter possessing negative inertial mass, a concept originated by
Bondi (1957) is shown to be logically impossible. On the other hand, the linked
ZPF-inertia and ZPF-gravity concepts open the conceptual possibility of
manipulation of inertia and gravitation, since both are postulated to be
electromagnetic phenomena. It is hoped that this will someday translate into
actual technological potential. A key question is whether the proposed
ZPF-matter interactions generating the phenomenon of mass might involve one or
more resonances. This is presently under investigation.Comment: Revised version of invited presentation at 34th AIAA/ASME/SAE/ASEE
Joint Propulsion Conference, July 13-15, 1998, Cleveland, OH, 10 pages, no
figure
Aspects of the Noisy Burgers Equation
The noisy Burgers equation describing for example the growth of an interface
subject to noise is one of the simplest model governing an intrinsically
nonequilibrium problem. In one dimension this equation is analyzed by means of
the Martin-Siggia-Rose technique. In a canonical formulation the morphology and
scaling behavior are accessed by a principle of least action in the weak noise
limit. The growth morphology is characterized by a dilute gas of nonlinear
soliton modes with gapless dispersion law with exponent z=3/2 and a superposed
gas of diffusive modes with a gap. The scaling exponents and a heuristic
expression for the scaling function follow from a spectral representation.Comment: 23 pages,LAMUPHYS LaTeX-file (Springer), 13 figures, and 1 table, to
appear in the Proceedings of the XI Max Born Symposium on "Anomalous
Diffusion: From Basics to Applications", May 20-24, 1998, Ladek Zdroj, Polan
The relationship between vertical leg stiffness and gross mechanical efficiency in cyclists
Background: Professional cyclists have been shown to have a mechanical efficiency that is 11% higher compared to amateur cyclists (Coyle et al. 1991: Med Sci Sports Exerc, 23 (1), 93-107). The variations in power between professional and amateur cyclists are associated with a greater torque development at the first phase of the pedal revolution (Coyle et al. 1991). It has also been shown in cyclists that a relationship exists between vertical leg stiffness and the peak power output (PPO) (r = 0.75, p < 0.01) achieved during a 30 s Wingate test (Pitchers et al. 2013: The relationship of vertical leg stiffness, peak power output and VÌO2max in recreationally active cyclists: identification of the interface between human and bike. 9th Annual Conference of the United Kingdom Strength & Conditioning Association, Nottingham, UK). Vertical leg stiffness may be important to cycling performance as the majority of the force produced is vertical and optimisation of the stretch shortening cycle may limit energy wastage during the propulsive phase (So et al. 2005: Phys Ther Sports, 6, 89-96; Fonda & Sarabon 2010: Sport Sci Rev, 19 (1), 187-210). The relationship between vertical leg stiffness and mechanical efficiency during cycling has yet to be examined. \ud
Purpose: To assess the relationship between vertical leg stiffness and gross mechanical efficiency (GE) in cycling. \ud
Methods: In a single group, within subjects design, 11 recreationally active male cyclists (age 34 ± 6 y, VÌO2max 57.4 ± 7.5 mlâkgâmin-1, body mass 81 ± 1.2 kg, stature 1.81 ± 0.06 m) completed two testing sessions, with a minimum of 48 hr rest between each session. In the first testing session participants completed a stiffness familiarisation before an incremental cycle test to establish VÌO2max. At the second session participants completed 20 sub-maximal bilateral hops at a frequency of 2.3 Hz. This was followed by three 8 min sub-maximal cycling bouts at 50, 55 and 60 % of the participantsâ individual maximal minute power (MMP) to establish GE (Table I). \ud
Results: Mean values for GE and vertical leg stiffness were 19.0 ± 1.4 % and 34.1 ± 9.0 kNâm-1, respectively. Pearsonâs correlation coefficient revealed no relationship between vertical leg stiffness and GE (r = -0.07, p = 0.85). \ud
Discussion: The main finding is that in recreationally active male cyclists there is no relationship between vertical leg stiffness and GE. In this group these findings indicate that GE is likely influenced more by other biological systems rather than the mechanical properties of the musculoskeletal system. However, these data may not be reflective of an elite sample where higher leg stiffness might be more likely to influence GE at higher power outputs.\ud
Conclusion: Whilst vertical leg stiffness has been shown to have a strong relationship with PPO (Pitchers et al 2013) in recreational cyclists, this is not the case for GE. Further work is needed to establish if this is also the case in an elite population
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