242 research outputs found

    Orienting coupled quantum rotors by ultrashort laser pulses

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    We point out that the non-adiabatic orientation of quantum rotors, produced by ultrashort laser pulses, is remarkably enhanced by introducing dipolar interaction between the rotors. This enhanced orientation of quantum rotors is in contrast with the behavior of classical paired rotors, in which dipolar interactions prevent the orientation of the rotors. We demonstrate also that a specially designed sequence of pulses can most efficiently enhances the orientation of quantum paired rotors.Comment: 7 pages, 5 figures, to appear in Phys. Rev.

    A newly discovered membrane at the origin of the proximal tendinous complex of the rectus femoris

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    Acord transformatiu CRUE-CSICPurpose: The rectus femoris (RF) forms the anterior portion of the quadriceps muscle group. It has a proximal tendinous complex (PTC) which is constituted by a direct tendon (DT), an indirect tendon (IT), and a variable third head. Direct and indirect tendons finally converge into a common tendon (CT). All the PTC shows a medially sloping in its proximal insertion.We investigated several anatomical specimens and discovered a new component: a membrane connecting the CT with the anterior superior iliac spine. Such membrane constitutes a new origin of the PTC. The aim of this study was to clarify whether this membrane was an anatomical variation of the PTC or a constant structure and to describe its morphology and trajectory. Material and methods: We dissected 42 cadaveric lower limbs and examined the architecture of the PTC. We paid special attention to the morphology and interaction patterns between the tendons and the membrane. Results: We demonstrated that the membrane is a constant component of the PTC. It has a lateral to medial trajectory and is in relation to the common tendon, the DT, and IT, which present a medial slope. This suggests that the membrane has an stabilizer role for the PTC, acting as a corrector of the inclined vector of the complex. Conclusion: The RF injuries are frequent in football. The newly discovered membrane is a constant component of the PTC and its integrity should be included in the algorithm to diagnose injuries

    Particular aspects of cerebral metastases secondary to malignant melanoma in comparison with other brain metastases

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    Authors present a retrospective study of 427 patients with brain metastases admitted and treated in third and fourth neurosurgical departments of Emergency Clinical Hospital “Bagdasar-Arseni” Bucharest, from January, 2005 until December, 2014. 62.1% of all patients were men and 37.9% were women, with a medium age of 56.8 years, ranging between 17 and 85 years. 311 patients (72.8%) had a single metastasis, 79 patients (18.5%) developed 2 or 3 metastases and 37 patients (8.7%) had more than 3 metastases. The biggest four metastases in multiple cases were noted in database regarding location, either reported to left / right hemisphere, either related to site (frontal parietal etc.), and dimensions. In the case of malignant melanoma (22 men and 24 women) the status of the primary tumor was noted: the malignant melanoma was operated in 32 cases (69.6%) and in 7 patients (15.2%) the primary tumor was not operated. In another 7 cases the status of the primary tumor was not noted. The most frequent location for malignant melanoma was the legs in women and anterior thorax in men. In conclusion, cerebral metastases from malignant melanoma have most frequent intratumoral hemorrhages, comparative with other primary sources. Common primary sites founded in this study is legs in women and anterior thorax in men. Treatment of cerebral metastases is complex, multimodal, implying neurosurgeons, oncologists and radiotherapists

    To dd, or not to dd: Recent developments and comparisons of regularization schemes

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    We give an introduction to several regularization schemes that deal with ultraviolet and infrared singularities appearing in higher-order computations in quantum field theories. Comparing the computation of simple quantities in the various schemes, we point out similarities and differences between them.Comment: 61 pages, 12 figures; version sent to EPJC, references update

    Traumatic lumbar Spondylolisthesis: Case Report

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    Only few cases of traumatic spondylolisthesis (from the cranial to lumbosacral joint) have been reported to date. Recovery of neurological function is dependent on the time of decompression and stabilization. We highlight the paramount importance that the time past between injury and surgical decompression have on neurological recovery and implant durability. Authors present the case of a 26 years old patient who suffered a motor crash 10 days ago before admission in our institution for cauda equina syndrome (L5 level). He also presented abdominal trauma with left kidney contusion, spleen contusion, thoracic contusion and left fibular fracture. X-ray and MRI examinations of the lumbosacral spine revealed grade 3 of spondylolistesis (60% anterior dislocation L5 - S1, intervertebral disc and posterior ligaments laceration, severe compression of the dural sac and dural laceration with CSF leakage through the posterior muscular mass). Surgery performed 14 days after the injury consisted in a posterior approach with L5 laminectomy, dural decompression and duroplasty with fascia lata, segmental reduction and stabilization with transpedicular screws, L5-S1 discectomy and anterior intervertebral grafting with two tricortical iliac crest grafts. Posterior lumbar interbody fusion was carried out using titanium screws (Solas system). Decompression, reduction with L5, S1 pedicular screw fixation, L5 – S1 disc excision and anterior intervertebral grafting with two tricortical iliac crest grafts is an appropriate surgical technique wich offer a good stabilization and fine functional recovering

    Exercise-Based Strategies to Prevent Muscle Injury in Male Elite Footballers: An Expert-Led Delphi Survey of 21 Practitioners Belonging to 18 Teams from the Big-5 European Leagues.

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    PurposeTo define based on expert opinion and practical experience using a systematic and scientific approach, (1) the perceived most effective exercise-based strategies to prevent muscle injury in elite footballers; and, (2) when and how these exercise programs are prescribed based on the number of days between games i.e. implementation strategy.MethodsA Delphi survey obtained opinions and assessed for agreement. Delphi respondents consisted of 21 experienced sports practitioners (12 ± 5.3 years in elite football and with an academic background) belonging to 18 teams from the Big-5 European football leagues; England, France, Germany, Italy, Spain. Three teams were represented collaboratively by two experts. The Delphi process involves sequential rounds each evolving based on the responses from the previous. The number of rounds is not pre-defined and continues until an agreement is either achieved or it is clear that no agreement will be reached. Frequency of responses was recorded where the agreement was sought (i.e. in closed questions) and an agreement was achieved if ≄ 13/18 (70%) respondents agreed. For open-ended questions, a qualitative content analysis was performed to identify recurring themes and when themes were specified by ≄ 13 (70%), these were also considered as reaching an agreement. Practitioners had the opportunity to raise concerns if they disagreed with the 'agreement from recurrent themes'.ResultsThere were four Delphi rounds (100% response for each round). Sprinting and High-Speed Running (HSR) focused exercises were agreed as most effective (perceived) to prevent muscle injuries. Eccentric exercise was perceived as the next most effective. It was agreed that sprinting and HSR be integrated into coaches training, and target 100% of players worst-case match scenario (e.g. volume, intensity) based on individual maximum speeds. Eccentric exercise was recommended to be implemented according to the context of the main football session and planned/actual sprinting and HSR content. It was agreed that eccentrics can be performed before or after training, context dependent. The day to perform specific sprinting and HSR or eccentric exercises depended on the proximity of previous and upcoming matches. Other exercises reaching agreement as 'somewhat effective' included concentric and isometric, horizontal and vertical plyometrics, coordination, core and dynamic flexibility in addition to core stability. No agreement was reached for multi-joint, resisted sprinting, kicking or agility exercises nor simultaneous single-leg strength and stability. Finally, no agreement was reached regarding programming variables e.g. sets, repetitions as deemed too contextual.ConclusionRegarding exercise-based strategies, particular importance agreed by the Delphi expert group was to focus on sprinting, HSR and eccentric exercises, integrated with a variety of other exercise modes which also carry some level of effectiveness in a multidimensional programme. Context was agreed to be key and decision-making about when to undertake/ how to prescribe exercise strategies to be made according to the content of normal football training and the proximity of matches

    A quantitative theory-versus-experiment comparison for the intense laser dissociation of H2+

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    A detailed theory-versus-experiment comparison is worked out for H2+_2^+ intense laser dissociation, based on angularly resolved photodissociation spectra recently recorded in H.Figger's group. As opposite to other experimental setups, it is an electric discharge (and not an optical excitation) that prepares the molecular ion, with the advantage for the theoretical approach, to neglect without lost of accuracy, the otherwise important ionization-dissociation competition. Abel transformation relates the dissociation probability starting from a single ro-vibrational state, to the probability of observing a hydrogen atom at a given pixel of the detector plate. Some statistics on initial ro-vibrational distributions, together with a spatial averaging over laser focus area, lead to photofragments kinetic spectra, with well separated peaks attributed to single vibrational levels. An excellent theory-versus-experiment agreement is reached not only for the kinetic spectra, but also for the angular distributions of fragments originating from two different vibrational levels resulting into more or less alignment. Some characteristic features can be interpreted in terms of basic mechanisms such as bond softening or vibrational trapping.Comment: submitted to PRA on 21.05.200

    Undergraduate students as co-producers in the creation of first-year practical class resources

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    Undergraduate students are increasingly working with academic staff to evaluate and design teaching materials in Higher Education, thereby moving from being passive consumers of knowledge to genuine partners in their education. Here we describe a student partnership project run at the University of Cambridge, which aimed to improve undergraduate biology practical class teaching. Student interns were recruited to act as researchers, pedagogical consultants and producers of teaching resources. Research by the interns revealed that students with limited practical experience at high-school level tended to have lower confidence and more negative responses to first-year university practical classes than peers with more experience. Interns and academics therefore redesigned the workflow for practicals to include online pre- and post-practical tutorials to support understanding and consolidation of laboratory-based material, which included student-produced quizzes and videos. We reflect on the process of building the partnership, and explore the value of partnership approaches in Higher Education.This work was supported by the University of Cambridge Teaching and Learning Innovation Fund [AHAV]
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