6,136 research outputs found

    The complex Kohn variational method applied to N-d scattering

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    The three-nucleon ground state and the N--d scattering states are obtained using variational principles. The wave function of the system is decomposed into angular-spin-isospin channels and the corresponding two dimensional spatial amplitudes are expanded in a correlated polynomial basis. For the scattering states, the complex form of the Kohn variational principle is used to determine the SS--matrix. Special attention is given to the convergence pattern of the phase-shift and mixing parameters. The calculations have been performed using realistic local NN potentials and three-nucleon forces. Important features of the method are anomaly-free solutions and the low dimensionality of the matrices involved allowing for the inclusion of a large number of states. Very precise and stable numerical results have been obtained.Comment: Latex, 22 pages; 5 figure

    Pressure dependence of the sound velocity in a 2D lattice of Hertz-Mindlin balls: a mean field description

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    We study the dependence on the external pressure PP of the velocities vL,Tv_{L,T} of long wavelength sound waves in a confined 2D h.c.p. lattice of 3D elastic frictional balls interacting via one-sided Hertz-Mindlin contact forces, whose diameters exhibit mild dispersion. The presence of an underlying long range order enables us to build an effective medium description which incorporates the radial fluctuations of the contact forces acting on a single site. Due to the non linearity of Hertz elasticity, self-consistency results in a highly non-linear differential equation for the "equation of state" linking the effective stiffness of the array with the applied pressure, from which sound velocities are then obtained. The results are in excellent agreement with existing experimental results and simulations in the high and intermediate pressure regimes. It emerges from the analysis that the departure of vL(P)v_{L}(P) from the ideal P1/6P^{1/6} Hertz behavior must be attributed primarily to the fluctuations of the stress field, rather than to the pressure dependence of the number of contacts

    Excavation and Survey in the Jabbul Plain, Western Syria: The Umm el-Marra Project 1996-1997

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    The 1996 and 1997 seasons of the Hopkins-Amsterdam project in the Jabbul plain, western Syria, have generated new results on Bronze Age urbanism at Tell Umm el- Marra and elucidated longer-term settlement patterns in the Jabbul region. Excavation results have documented the foundation of Umm el-Marra as a regional center in the Early Bronze Age, provided new data on a period of decentralization in Middle Bronze I, and supplied evidence of the regeneration of urbanism in MB II. Faunal and archaeobotanical analysis broaden our understanding of these developments, attesting to an economy overwhelmingly dependent on the steppe environment, with an emphasis on large-scale onager hunting in MB II. Finally, a regional survey provides data on long-term demographic and socioeconomic trends, furnishing an expansive time range and spatial context for our under- standing of developmental patterns in the region. The survey results supply new information on the limits of the Uruk expansion, cycles of Bronze Age urbanization, changing patterns of steppe exploitation, and demo- graphic and agricultural extensification in the Byzantine and Early Islamic periods

    Feasibility of Photofrin II as a radiosensitizing agent in solid tumors - Preliminary results

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    Background: Photofrin II has been demonstrated to serve as a specific and selective radiosensitizing agent in in vitro and in vivo tumor models. We aimed to investigate the feasibility of a clinical application of Photofrin II. Material and Methods: 12 patients were included in the study (7 unresectable solid tumors of the pelvic region, 3 malignant gliomas, 1 recurrent oropharyngeal cancer, 1 recurrent adenocarcinoma of the sphenoid sinus). The dose of ionizing irradiation was 30-50.4 Gy; a boost irradiation of 14 Gy was added for the pelvic region. All patients were intravenously injected with 1 mg/kg Photofrin II 24 h prior to the commencement of radiotherapy. Magnetic resonance imaging (MRI) controls and in some cases positron emission tomography (PET) were performed in short intervals. The mean follow-up was 12.9 months. Results: No major adverse events were noted. Minor adverse events consisted of mild diarrhea, nausea and skin reactions. A complete remission was observed in 4/12 patients. A reduction in local tumor volume of > 45% was achieved in 4/12 patients. Stable disease was observed in 4/12 patients. 1 patient showed local disease progression after 5 months. Conclusion: The early follow-up results are encouraging regarding the feasibility of the application of Photofrin II as a radiosensitizing agent

    Human-derived nanoparticles and vascular response to injury in rabbit carotid arteries: Proof of principle

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    Self-calcifying, self-replicating nanoparticles have been isolated from calcified human tissues. However, it is unclear if these nanoparticles participate in disease processes. Therefore, this study was designed to preliminarily test the hypothesis that human-derived nanoparticles are causal to arterial disease processes. One carotid artery of 3 kg male rabbits was denuded of endothelium; the contralateral artery remained unoperated as a control. Each rabbit was injected intravenously with either saline, calcified, or decalcified nanoparticles cultured from calcified human arteries or kidney stones. After 35 days, both injured and control arteries were removed for histological examination. Injured arteries from rabbits injected with saline showed minimal, eccentric intimal hyperplasia. Injured arteries from rabbits injected with calcified kidney stone- and arterial-derived nanoparticles occluded, sometimes with canalization. The calcified kidney stone-derived nanoparticles caused calcifications within the occlusion. Responses to injury in rabbits injected with decalcified kidney stone-derived nanoparticles were similar to those observed in saline-injected animals. However, decalcified arterial-derived nanoparticles produced intimal hyperplasia that varied from moderate to occlusion with canalization and calcification. This study offers the first evidence that there may be a causal relationship between human-derived nanoparticles and response to injury including calcification in arteries with damaged endothelium

    A new approach to generating research-quality data through citizen science: The USA National Phenology Monitoring System

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    Phenology is one of the most sensitive biological responses to climate change, and recent changes in phenology have the potential to shake up ecosystems. In some cases, it appears they already are. Thus, for ecological reasons it is critical that we improve our understanding of species’ phenologies and how these phenologies are responding to recent, rapid climate change. Phenological events like flowering and bird migrations are easy to observe, culturally important, and, at a fundamental level, naturally inspire human curiosity— thus providing an excellent opportunity to engage citizen scientists. The USA National Phenology Network has recently initiated a national effort to encourage people at different levels of expertise—from backyard naturalists to professional scientists—to observe phenological events and contribute to a national database that will be used to greatly improve our understanding of spatio-temporal variation in phenology and associated phenological responses to climate change.

Traditional phenological observation protocols identify specific dates at which individual phenological events are observed. The scientific usefulness of long-term phenological observations could be improved with a more carefully structured protocol. At the USA-NPN we have developed a new approach that directs observers to record each day that they observe an individual plant, and to assess and report the state of specific life stages (or phenophases) as occurring or not occurring on that plant for each observation date. Evaluation is phrased in terms of simple, easy-to-understand, questions (e.g. “Do you see open flowers?”), which makes it very appropriate for a citizen science audience. From this method, a rich dataset of phenological metrics can be extracted, including the duration of a phenophase (e.g. open flowers), the beginning and end points of a phenophase (e.g. traditional phenological events such as first flower and last flower), multiple distinct occurrences of phenophases within a single growing season (e.g multiple flowering events, common in drought-prone regions), as well as quantification of sampling frequency and observational uncertainties. These features greatly enhance the utility of the resulting data for statistical analyses addressing questions such as how phenological events vary in time and space, and in response to global change. This new protocol is an important step forward, and its widespread adoption will increase the scientific value of data collected by citizen scientists.
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    Theory of superconductor-insulator transition in single Josephson junctions

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    A non-band theory is developed to describe the superconductor-insulator (SI) transtition in resistively shunted, single Josephson junctions. The Iāˆ’VI-V characteristic is formulated by a Landauer-like formula and evaluated by the path-integral transfer-matrix method. The result is consistent with the recent experiments at around 80 mKmK. However, the insulator phase shrinks with decreasing temperature indicating that the single Josephson junction becomes all superconducting at absolute zero temperature, as long as dissipation is present.Comment: 4 pages, 3 figure

    The relationship between types of childhood victimisation and young adulthood criminality

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    BackgroundPrevious research suggests that some types of childhood abuse and neglect are related to an increased likelihood of perpetrating criminal behaviour in adulthood. Little research, however, has examined associations between multiple different types of childhood victimisation and adult criminal behaviour.AimsWe sought to examine the contribution of multiple and diverse childhood victimisations on adult criminal behaviour. Our central hypothesis was that, after controlling for gender, substance use and psychopathy, each type of childhood victimisation Ć¢ specifically experience of property offences, physical violence, verbal abuse, sexual abuse, neglect and witnessed violence Ć¢ would be positively and independently related to criminal behaviour in young adults.MethodsWe examined data from a large, nationally representative sample of 2244 young Swedish adults who reported at least one form of victimisation, using hierarchical regression analysis to also account for gender, substance use and psychopathy.ResultsExperiences of physical assaults, neglect and witnessing violence as a child were significantly associated with adult criminal behaviour, but not experiences of property, verbal or sexual victimizations.ConclusionsOur findings help to identify those forms of harm to children that are most likely to be associated with later criminality. Even after accounting for gender, substance misuse and psychopathology, childhood experience of violence Ć¢ directly or as a witness Ć¢ carries risk for adulthood criminal behaviour, so such children need targeted support and treatment. Copyright ƂĀ© 2016 John Wiley & Sons, Ltd.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138903/1/cbm2002.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138903/2/cbm2002_am.pd

    Th1/Th2 cytokines and ICAM-1 levels post-liver transplant do not predict early rejection.

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    Th1 derived cytokines IFN-gamma and IL-2, Th2 cytokine IL-4, and ICAM-1 have been implicated in liver allograft rejection. In order to determine whether monitoring of cytokine profiles during the first days post-liver transplant can predict early rejection we measured IFN-gg, IL-2, sIL-2 receptor, IL-4 and ICAM-1 in 22 patients, in plasma samples obtained within 4 h after liver perfusion (baseline) and between postoperative days (POD) 3-6. ICAM-1 and sIL-2R levels at POD 3-6 were significantly higher than at baseline but did not differ in presence or absence of rejection. Mean percentage increase of ICAM-1 levels was significantly lower in patients with Muromonab-C3 Orthoclone OKT3 (J.C. Health Care) (OKT3) whereas percentage increase of sIL-2R levels was higher in OKT3-treated patients. IFN-gamma levels at POD 3-6 increased from baseline while IL-4 levels were unchanged. Levels of IFN-gamma, IL-4 and their ratios did not correlate with rejection or immunosuppressive therapy. Thus, Th1/Th2 cytokine monitoring during the first week post-transplant does not predict early rejection and immunosuppressive therapy is the predominant factor affecting ICAM and sIL-2R levels after liver transplantation
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