8,617 research outputs found
The general caloron correspondence
We outline in detail the general caloron correspondence for the group of
automorphisms of an arbitrary principal -bundle over a manifold ,
including the case of the gauge group of . These results are used to define
characteristic classes of gauge group bundles. Explicit but complicated
differential form representatives are computed in terms of a connection and
Higgs field.Comment: 25 pages. New section added containing example
Influence of growth rate on the immature skeleton
Bone architecture adapts to withstand the loads placed upon it. In response to increased loads during growth, bones circumferentially expand to increase their diameter through the incorporation of periosteal blood vessels and the formation and infilling of primary osteons. However, the influence of growth rate on bone architecture in the immature skeleton is not fully understood.
To investigate how bone architecture is modulated by growth rate, morphometric, biochemical and genetic comparisons were made between tibiae from broiler chickens with either fast or slow growth potentials.
Both strains of chickens were kept under identical conditions, and fed ad-libitum standard broiler feed. Tibiae were removed and tested by three-point bending to determine stiffness and breaking strength and cross sections of the tibia were examined histomorphologically. Bone stiffness and breaking strength were higher in the rapidly growing birds, but after adjustment for body weight the bones were inherently weaker. Cortical porosity periosteally, but not endosteally, was increased. Sections reacted for ALP and TRAP activity, and others stained for cement (reversal) lines indicated the absence of primary osteon remodelling in the periosteal region. This suggests that the increased periosteal porosity is due to slower infilling of the primary osteons in the rapidly growing birds. To directly quantify the rate of osteon infilling, tibiae were removed from 21-day-old chicks, which had been double labelled with calcein (80 and 8 h before death). The mineral apposition rate was higher in the slow growing chickens, and confirmined the previous histomorphometry results. Osteocyte density within the circumferential lamellae of the cortical bone was higher in the rapidly growing birds but unchanged within the newly laid down bone of the primary osteons.
Immunohistochemical staining of cortical bone sections from chickens injected with bromodeoxyuridine located proliferating pre-osteoblast cells to the osteogenic layer of the periosteum. A lower labelling index in the rapidly growing birds was seen across four circumferential areas of the periosteum (anterior = fast growing area, posterior = slow growing area, medial and lateral = intermediate growing areas), even though the osteogenic layer of the periosteum was thicker in the fast strain. Blood vessel numbers within the periosteum was similar between strains but differed between regions habitually loaded in tension (anterior) or in compression (posterior).
Osteoblasts were grown and expanded in culture from explants of tibia cortical bone (periosteum removed) of 21-day-old birds of both strains (n=4/strain). Osteoblast proliferation was determined by tritiated-thymidine uptake and differentiation by alkaline phosphatase (ALP) activity. At pre-confluency, cell proliferation was higher in the slow growing birds, but this pattern was reversed at confluency and post confluency which was a likely consequence of impairment of proliferation by contact inhibition in the slow growing strain. ALP activity was only detected at post-confluency and was higher in the fast growing strain. Osteoblastic gene expression was determined by RT-PCR and quantified by densitometry. A higher level of osteopontin, and bone sialoprotein expression (BSP) was observed in the slow growing birds. Whereas Runx2 and the serotonin receptor, considered to have a role in mechanoregulation, were more highly expressed in the fast chickens.
In conclusion, fast growth resulted in the expected circumferential expansion to increase bone bending strength. Fast growth was accompanied by increased porosity resulting from the rapid formation of primary osteons and the incapacity of osteoblasts to completely infill the resultant canal. However, periosteal interstitial bone of the fast growing birds had a higher osteocyte density suggesting that the lack of infilling was not due to a decrease in osteoblast number. No evidence was obtained to suggest that osteonal remodelling or periosteal blood vessel number were a determinant for primary osteon size. However, the lower labelling index at the periosteum and increased osteocyte density within the circumferential lamellae of the fast strain suggests an increase in transit time through the osteoblast lineage at the periosteal surface. In vitro, osteoblast proliferation was faster in the slow growing birds whereas differentiation was slower. This is in accord with the previous hypothesis that the fast growing birds are characterised by an increase in transit time through the osteoblast lineage, which may be driven by the high levels of Runx2 expression. Osteopontin and BSP are associated with mechanical loading but the significance of the lower expression levels in the fast growing birds requires further study. However, the up regulation of serotonin expression may reflect the greater loads experienced in the fast growing birds in vivo
Iowa State Welcomes New Dean of Home Economics: Faculty Adds Fifteen to Staff
With the arrival of Miss Anna J. Richardson in Ames in time for winter quarter registration, Iowa State will welcome her new dean of the Home Economics division. Miss Edna Walls, who has served as acting dean since the death of Dean MacKay in August, 1921, will continue as vice-dean
The public health potential of the current health apps for increasing physical activity
I consider my PhD as having 2 distinctive parts: A) to ascertain the quality of physical activity (PA) applications (apps) on the market in terms of safety, effectiveness, and user experience (Studies 1, 2); B) to assess the efficacy of selected PA apps with potential, physically inactive, users (Studies 3, 4). I am finalising part A of the PhD and I am writing the protocols for part B. It would be valuable to gain the views of experts to make sure I am considering the topic from both behaviour change discipline and user experience research
The caloron correspondence and higher string classes for loop groups
We review the caloron correspondence between -bundles on
and -bundles on , where is the space of smooth loops in
the compact Lie group . We use the caloron correspondence to define
characteristic classes for -bundles, called string classes, by
transgression of characteristic classes of -bundles. These generalise the
string class of Killingback to higher dimensional cohomology.Comment: 21 pages. Author addresses adde
Relationship between popularity and the likely efficacy: an observational study based on a random selection on top-ranked physical activity apps
Objectives To explore the relationship between popularity of mobile application (apps) for physical activity (PA) and their likely efficacy. The primary objective was to assess the association between app popularity (indicated by user ratings) and likely efficacy (indicated by the number of Behaviour Change Techniques (BCT) present). The secondary objective was to assess the relationship between user ratings and those BCTs that have been shown to be effective in increasing PA.
Design Observational study.
Methods 400 top-ranked free and paid apps from iTunes and Google Play stores were screened, and were included if the primary behaviour targeted was PA and they had stand-alone functionality. The outcome variable of user rating was dichotomised into high (4, 5 stars) or low (1, 2, 3 stars) rating.
Setting iTunes and Google Play app stores.
Participants No individual participants but the study used user-led rating system in the app store.
Primary and secondary outcome measures BCTs and user rating.
Results Of 400 apps, 156 were eligible and 65 were randomly selected, downloaded and assessed by two reviewers. There was no relationship overall between star ratings and the number of BCTs present, nor between star ratings and the presence of BCTs known to be effective in increasing PA. App store was strongly associated with star ratings, with lower likelihood of finding 4 or 5 stars in iTunes compared with Google Play (OR 0.74, 95% CI 0.73 to 0.76, p<0.001).
Conclusions The findings of this study suggest that popularity does not necessarily imply the likelihood of effectiveness. Hence, public health impact is unlikely to be achieved by allowing market forces to ‘prescribe’ what is used by the public
A scoping review of the resources needed to deliver anterior cruciate ligament physiotherapy rehabilitation in randomised controlled trials
Background: The Anterior Cruciate Ligament (ACL) stabilises the knee and is commonly injured in sport. Surgical repair and rehabilitation are common. However, rehabilitation randomised controlled trials do not always report the resources used to deliver ACL rehabilitation. This may lead to suboptimal availability of resources for evidence based care.
Objective: To identify the resources used to deliver multimodal ACL rehabilitation in randomised controlled trials
Methods: Comprehensive searches, combining ‘anterior cruciate ligament’, and ‘rehabilitation’ with the Cochrane RCT filter, were conducted of Medline, Embase, Cinahl, PeDro, Sports Discus and the Cochrane Library. Adults post ACL reconstruction were included. The intervention and comparator were physiotherapy for post-operative rehabilitation. Outcomes were the resources required to deliver rehabilitation, and study type was randomised controlled trials. Papers were screened against the criteria; data were charted and narrative synthesis applied.
Results: Fourteen studies reported on 599 patients. The interventions ranged from 4 to 36 weeks. Physiotherapy was typically an hour and ranged from 1 to 5 sessions/week. Resources included a gym environment with rehabilitation equipment such as resistance machines, free weights, cardiovascular and neuromuscular control equipment, and an experienced physiotherapist.
Conclusions: Implications for future studies include the need for a more detailed report of the resources used in RCTs. Accurate reporting would help healthcare decision makers to effectively manage resources when implementing evidence based care. Findings can be considered as criteria against which to audit resource provision
A Historical Perspective on Decentralisation and Service Delivery for Socioeconomic Development in Papua New Guinea
Papua New Guinea (PNG) has over 800 different language groups. Decentralisation in PNG continues to devolve from central government. This paper considers government service delivery through decentralisation mechanisms noting provincial and local level governments have often inadequately facilitated service delivery. The 2014 District Development Authorities enabled provincial governments to be bypassed, thus reducing bureaucratic and administrative wastage, eliminate cultural and tribal politics, and delivering basic socioeconomic services directly at the district level
Quality of Publicly Available Physical Activity Apps: Review and Content Analysis
BACKGROUND: Within the new digital health landscape, the rise of health apps creates novel prospects for health promotion. The market is saturated with apps that aim to increase physical activity (PA). Despite the wide distribution and popularity of PA apps, there are limited data on their effectiveness, user experience, and safety of personal data. OBJECTIVE: The purpose of this review and content analysis was to evaluate the quality of the most popular PA apps on the market using health care quality indicators. METHODS: The top-ranked 400 free and paid apps from iTunes and Google Play stores were screened. Apps were included if the primary behavior targeted was PA, targeted users were adults, and the apps had stand-alone functionality. The apps were downloaded on mobile phones and assessed by 2 reviewers against the following quality assessment criteria: (1) users' data privacy and security, (2) presence of behavior change techniques (BCTs) and quality of the development and evaluation processes, and (3) user ratings and usability. RESULTS: Out of 400 apps, 156 met the inclusion criteria, of which 65 apps were randomly selected to be downloaded and assessed. Almost 30% apps (19/65) did not have privacy policy. Every app contained at least one BCT, with an average number of 7 and a maximum of 13 BCTs. All but one app had commercial affiliation, 12 consulted an expert, and none reported involving users in the app development. Only 12 of 65 apps had a peer-reviewed study connected to the app. User ratings were high, with only a quarter of the ratings falling below 4 stars. The median usability score was excellent-86.3 out of 100. CONCLUSIONS: Despite the popularity of PA apps available on the commercial market, there were substantial shortcomings in the areas of data safety and likelihood of effectiveness of the apps assessed. The limited quality of the apps may represent a missed opportunity for PA promotion
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