777 research outputs found
Spin-Dependent Twist-Four Matrix Elements from g_1 Data in the Resonance Region
Matrix elements of spin-dependent twist-four operators are extracted from
recent data on the spin-dependent g_1 structure function of the proton and
deuteron in the resonance region. We emphasize the need to include the elastic
contributions to the first moments of the structure functions at Q^2 < 2 GeV^2.
The coefficients of the 1/Q^2 corrections to the Ellis-Jaffe sum rules are
found to be 0.04 \pm 0.02 and 0.03 \pm 0.04 GeV^2 for the proton and neutron,
respectively.Comment: 10 pages REVTeX, 4 figure
Chiral extrapolation of lattice moments of proton quark distributions
We present the resolution of a long-standing discrepancy between the moments
of parton distributions calculated from lattice QCD and their experimental
values. We propose a simple extrapolation formula for the moments of the
nonsinglet quark distribution u-d, as a function of quark mass, which embodies
the general constraints imposed by the chiral symmetry of QCD. The inclusion of
the leading nonanalytic behavior leads to an excellent description of both the
lattice data and the experimental values of the moments.Comment: 9 pages, 1 figure, to appear in Physical Review Letter
Ethnic In-Group Favoritism Among Minority and Majority Groups: Testing the Self-Esteem Hypothesis Among Preadolescents
The self-esteem hypothesis in intergroup relations, as proposed by social identity
theory (SIT), states that successful intergroup discrimination enhances momentary
collective self-esteem. This hypothesis is a source of continuing controversy. Furthermore,
although SIT is increasingly used to account for children’s group attitudes,
few studies have examined the hypothesis among children. In addition, the
hypothesis’s generality makes it important to study among children from different
ethnic groups. The present study, conducted among Dutch and Turkish preadolescents,
examined momentary collective self-feelings as a consequence of ethnic group
evaluations. The results tended to support the self-esteem hypothesis. In-group
favoritism was found to have a self-enhancing effect among participants high in
ethnic identification. This result was found for ethnic majority (Dutch) and minority
(Turkish) participants.
Nonperturbative versus perturbative effects in generalized parton distributions
Generalized parton distributions (GPDs) are studied at the hadronic
(nonperturbative) scale within different assumptions based on a relativistic
constituent quark model. In particular, by means of a meson-cloud model we
investigate the role of nonperturbative antiquark degrees of freedom and the
valence quark contribution. A QCD evolution of the obtained GPDs is used to add
perturbative effects and to investigate the GPDs' sensitivity to the
nonperturbative ingredients of the calculation at larger (experimental) scale.Comment: 17 pages, 10 figures; submitted to Phys. Rev.
Serendipity in context: Prioritised contextual browsing in large-scale digital libraries
In previous work we proposed a model of information-seeking behaviour in scholarly workset creation, combining and extend-ing established models by Bates, Ellis, and Wilson to encompass strategies for scholarly research in large-scale information systems. However, this model simplifies contextual browsing, a key aspect of information seeking in large-scale information systems, as a single, holistic, strategy. Here, we extend this model with granular strategies for contextual browsing, defining new modes to characterise contextual browsing as combinations of these strategies, which we show to be consistent with ser-endipitous discovery as described by Makri et al. We study the properties of prioritised contextual browsing as a mechanism for implementing these strategies. We describe the Compage framework, a proof-of-concept implementation for prioritised contextual browsing of Linked Data resources, using Jaccard similarity for prioritisation. Extending Compage, we develop a simulation environment in which we investigate the utility of prioritised contextual browsing over a large-scale digital library dataset. Our simulation applies three strategies for the traversal of contextual metadata: reset, unprioritised, and prioritised. Results empirically demonstrate the advantages of prioritised contextual browsing, and that elements of serendipity can be identified and incorporated within our information-seeking model. In doing so, we evaluate our model's suitability for this scenario, yielding a more detailed understanding of the strategies and modes of behaviour underlying contextual browsing
On providing semantic alignment and unified access to music library metadata
A variety of digital data sources---including institutional and formal digital libraries, crowd-sourced community resources, and data feeds provided by media organizations such as the BBC---expose information of musicological interest, describing works, composers, performers, and wider historical and cultural contexts. Aggregated access across such datasets is desirable as these sources provide complementary information on shared real-world entities. Where datasets do not share identifiers, an alignment process is required, but this process is fraught with ambiguity and difficult to automate; whereas manual alignment may be time-consuming and error-prone. We address this problem through the application of a Linked Data model and framework to assist domain experts in this process. Candidate alignment suggestions are generated automatically based on textual and on contextual similarity. The latter is determined according to user-configurable weighted graph traversals. Match decisions confirming or disputing the candidate suggestions are obtained in conjunction with user insight and expertise. These decisions are integrated into the knowledge base, enabling further iterative alignment, and simplifying the creation of unified viewing interfaces. Provenance of the musicologist's judgement is captured and published, supporting scholarly discourse and counter-proposals. We present our implementation and evaluation of this framework, conducting a user study with eight musicologists. We further demonstrate the value of our approach through a case study providing aligned access to catalogue metadata and digitised score images from the British Library and other sources, and broadcast data from the BBC Radio 3 Early Music Show
Breast Ultrasound Following a Positive Clinical Breast Examination: Does It Have a Role in Low- and Middle-Income Countries?
Purpose: Breast cancer is the most common cancer among women worldwide, with an estimated 1.7 million new cases occurring in 2012. The majority of cases and deaths occur in low- and middle-income countries (LMICs), where population-based mammography screening is not available and countries must rely on clinical breast examination (CBE). Since ultrasound has the potential to reduce unnecessary biopsies by triaging women with palpable or focal breast findings at CBE, we searched for evidence in the literature on the effectiveness of ultrasound in detecting potential breast cancer following positive CBE findings.
Methods: We reviewed the literature from 2000 to 2014 for evidence on the performance of breast ultrasound, in the absence of mammography, used to evaluate women after a positive CBE. From the studies meeting our inclusion/exclusion criteria for our analysis, we extracted data on the study design, location, ultrasound transducer parameters, patient age, method for determining positive and negative cases, and number of malignancies detected/total number of women studied.
Results: We found 15 studies matching our inclusion/exclusion criteria, 9 from high-income countries and 6 from LMICs. Despite considerable variability in study design and patient populations, breast ultrasound consistently showed high sensitivity (median = 94 percent) and specificity (median = 80 percent) for detecting breast cancer and identifying normal and benign findings not requiring a biopsy. Clear patterns related to transducer frequency or income level were not discernible given the variations in patient populations and final diagnostic determinations.
Conclusion: Our systematic review suggests that breast ultrasound following a positive CBE may be a powerful diagnostic test to determine those who do or do not need biopsy. We encourage further research in breast ultrasound use after a positive CBE in LMICs to assess the accuracy of ultrasound in these settings and the feasibility of widespread implementation
A comparison of multidisciplinary team residential rehabilitation with conventional outpatient care for the treatment of non-arthritic intra-articular hip pain in UK Military personnel:a protocol for a randomised controlled trial
BACKGROUND: Non-arthritic hip disorders are defined as abnormalities of the articulating surfaces of the acetabulum and femur before the onset of osteoarthritis, including intra-articular structures such as the acetabular labrum and chondral surfaces. Abnormal femoroacetabular morphology is commonly seen in young men who constitute much of the UK military population. Residential multidisciplinary team (MDT) rehabilitation for patients with musculoskeletal injuries has a long tradition in the UK military, however, there are no studies presenting empirical data on the efficacy of a residential MDT approach compared with individualised conventional outpatient treatment. With no available data, the sustainability of this care pathway has been questioned. The purpose of this randomised controlled trial is to compare the effects of a residential multidisciplinary intervention, to usual outpatient care, on the clinical outcomes of young active adults undergoing treatment for non-arthritic intra-articular hip pain. METHODS/DESIGN: The trial will be conducted at the Defence Medical Rehabilitation Centre, Headley Court, UK. One hundred military male participants with clinical indicators of non-arthritic intra-articular hip pain will be randomly allocated to either: (1) 7-day residential multidisciplinary team intervention, n = 50; (2) 6-week physiotherapist-led outpatient intervention (conventional care), n = 50. Measurements will be taken at baseline, post-treatment (1-week MDT group; 6-weeks physiotherapy group), and 12-weeks. The primary outcome measures are the function in daily living sub-scale of the Copenhagen Hip and Groin Outcome Score (HAGOS), the physical function subscale of the Non-arthritic Hip Score (NAHS), and VAS pain scale. Secondary outcomes include objective measures of physical capacity and general health. An intention-to-treat analysis will be performed using linear and mixed models. DISCUSSION: This study will be the first to assess the efficacy of intensive MDT rehabilitation, versus conventional outpatient care, for the management of non-arthritic hip pain. The results from this study will add to the evidence-base and inform clinical practice for the management of intra-articular non-arthritic hip pain and femoroacetabular impingement in young active adults. TRIAL REGISTRATION: ISRCTN Reference: ISRCTN 59255714 dated 11-Nov-2015 ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12891-016-1309-z) contains supplementary material, which is available to authorized users
Evidence of re-osseointegration after electrolytic cleaning and regenerative therapy of peri-implantitis in humans: a case report with four implants.
OBJECTIVE
To evaluate re-osseointegration after electrolytic cleaning and regenerative therapy of dental implants with peri-implantitis in humans.
MATERIAL AND METHODS
Four dental implants that developed peri-implantitis underwent electrolytic cleaning followed by regenerative therapy with guided bone regeneration. All four implants developed recurrent peri-implantitis and were therefore explanted 6 to 13 months later. Radiographic bone level, probing depth, and bleeding on probing were determined at the time of surgery, 6 months later, and before implant retrieval. The peri-implant tissues were histologically and histomorphometrically analyzed.
RESULTS
All four implants demonstrated radiographic and histological bone gain, reduced probing depth, and bleeding on probing. Radiographic bone gain was 5.8 mm mesially and 4.8 mm distally for implant #1, 3.3 mm and 2.3 mm for implant #2, 3.1 mm and 0.5 mm for implant #3, and 3.5 mm and 2.8 mm for implant #4. The histometric mean and maximum vertical bone gain for implant #1 to #4 was 1.65 mm and 2.54 mm, 3.04 mm and 3.47 mm, 0.43 mm and 1.27 mm, and 4.16 mm and 5.22 mm, respectively. The percentage of re-osseointegration for implant #1 to #4 was 21.0%, 36.9%, 5.7%, and 39.0%, respectively. In one implant, the newly formed bone was deposited directly onto calculus on the implant surface.
CONCLUSIONS
We found that (1) re-osseointegration is possible on a formerly contaminated implant surface and (2) the electrolytic cleaning process seems to be effective enough at sites with calculus residues.
CLINICAL RELEVANCE
Since re-osseointegration can be achieved by electrolytic cleaning, this decontamination technique may be considered as a future treatment concept
Optimization of insect cell based protein production processes - online monitoring, expression systems, scale-up
Due to the increasing use of insect cell based expression systems in research and industrial recombinant protein production, the development of efficient and reproducible production processes remains a challenging task. In this context, the application of online monitoring techniques is intended to ensure high and reproducible product qualities already during the early phases of process development. In the following chapter, the most common transient and stable insect cell based expression systems are briefly introduced. Novel applications of insect cell based expression systems for the production of insect derived antimicrobial peptides/proteins (AMPs) are discussed using the example of G. mellonella derived gloverin. Suitable in situ sensor techniques for insect cell culture monitoring in disposable and common bioreactor systems are outlined with respect to optical and capacitive sensor concepts. Since scale-up of production processes is one of the most critical steps in process development, a conclusive overview is given about scale up aspects for industrial insect cell culture processes
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