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We present a theoretical study of the processes d(d,p)^{3}H and d(d,n)^{3}He at energies of interest for energy production and for big-bang nucleosynthesis. We accurately solve the four body scattering problem using the ab initio hyperspherical harmonics method, starting from nuclear Hamiltonians which include modern two- and three-nucleon interactions, derived in chiral effective field theory. We report results for the astrophysical S factor, the quintet suppression factor, and various single and double polarized observables. A first estimate of the theoretical uncertainty for all these quantities is provided by varying the cutoff parameter used to regularize the chiral interactions at high momentum.
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PURPOSE: Ethical questions are poorly investigated specifically in radiation oncology. The objective of the study was to identify and understand the main ethical issue in radiation oncology. MATERIALS AND METHODS: A quantitative analysis was based on the answers to a questionnaire of 200 professionals from 22 radiation oncology departments. The questionnaire mainly aimed to characterize the main ethical issue. A monocentric qualitative analysis was based on semi-structured interviews focused on the main identified ethical issue, carried out with eight technologists, and 20 patients undergoing radiotherapy. RESULTS: The main ethical issue was the understanding and/or acceptance of the treatment by the patients (71 %), which frequently arises (more than once a month) (52 %), and corresponds to an ethical tension between the principles of respect for autonomy and beneficence (the good as viewed by the patient) as defined by Beauchamp and Childress. The technologists, wish the patient to be fully involved in his treatment, with the even possibility of refusing it. However, excluding paternalism and autonomic relentlessness, the technologists have the feeling of acting for the good of the patients by treating them with radiation, even if the patients are not always aware of it, because they are within a situation of vulnerability. If the hierarchy of principles is a compromise alternative, this problem is finally well resolved by the effective implementation of an ethic of consideration and solicitude, restoring the patient capabilities, i.e. the maximum development of his potentialities in his situation of vulnerability. Beyond the legal dimension, patient information is crucial and must consider the specific temporality of the patient. CONCLUSION: The main ethical issue in radiation oncology is the understanding and/or acceptance of the treatment involving the development of an ethic of consideration and solicitude.
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Autonomia Pessoal , Radioterapia (Especialidade) , Humanos , Paternalismo , BeneficênciaRESUMO
The first Covid-19 lockdown changed medical and care practices. Although positive patients were prioritised and the focus was on the efficiency of the intensive care units, the relational aspect of care is central to the philosophy of French Care Centres for Support and Prevention in Addictology (CSAPA in French). The caregivers were impacted by restrictive aseptic protocols, with an increased risk of patients, that are already very vulnerable, abandoning or not following-up their treatment. Based on the case of Grasse CSAPA, the paper aims (1) to analyse, retrospectively, the ethical tensions triggered by the acceptance of otherness in patients with complex issues and (2) to highlight the inventiveness of the caregivers in their daily practice. The method is philosophical and conceptual and focuses on Levinas's ethics of the "face", because the crisis exacerbated pre-existing ethical tensions concerning intersubjectivity. Caregivers had to face up to a heightened ethical "responsibility for others". However, the crisis was also an opportunity to reinvest in relational care, by allowing them to detach from the primacy of sight: the masks sometimes helped and sometimes hindered care, revealing the shared vulnerability of both caregivers and patients. The health crisis reminds us that vigilance is always necessary with regard to the risks of dehumanising the relationship of care.
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The current study examined the impact of the lockdown due to the Covid-19 disease on mood state and behaviours of children and adolescents with ADHD. Nine hundred ninety-two parents of children and adolescents with ADHD filled out an anonymous online survey through the ADHD family association website. The survey investigated the degree of severity of six emotional and mood states (sadness, boredom, little enjoyment/interest, irritability, temper tantrums, anxiety) and five disrupted behaviours (verbal and physical aggression, argument, opposition, restlessness) based on their frequency/week (absent; low: 1-2 days/week; moderate: 3-4 days/week; severe: 5-7 days/week) before and during the lockdown. Important fluctuations were found in all dimensions during the lockdown independently by the severity degree. Subjects with previous low severity degree of these behaviors significantly worsened in almost all dimensions during the lockdown. On the contrary, ADHD patients with moderate and severe degree showed important improvement during the lockdown. Little enjoyment/interests and boredom resulted the dimensions more strongly affected by the condition of restriction, overall in children. Children vs. adolescents showed substantially similar trend but the former resulted significantly more vulnerable to emotive changes. The results provided both the individuation of domains affected, and the indirect benefits produced by restriction condition.
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Sintomas Afetivos/psicologia , Transtorno do Deficit de Atenção com Hiperatividade/psicologia , COVID-19/psicologia , Transtornos do Comportamento Infantil/psicologia , Isolamento Social , Adolescente , Agressão/psicologia , Ansiedade/diagnóstico , Ansiedade/psicologia , Transtornos de Ansiedade/psicologia , Tédio , Criança , Feminino , Humanos , Humor Irritável , Masculino , Fatores de Risco , Inquéritos e QuestionáriosRESUMO
Light elements were produced in the first few minutes of the Universe through a sequence of nuclear reactions known as Big Bang nucleosynthesis (BBN)1,2. Among the light elements produced during BBN1,2, deuterium is an excellent indicator of cosmological parameters because its abundance is highly sensitive to the primordial baryon density and also depends on the number of neutrino species permeating the early Universe. Although astronomical observations of primordial deuterium abundance have reached percent accuracy3, theoretical predictions4-6 based on BBN are hampered by large uncertainties on the cross-section of the deuterium burning D(p,γ)3He reaction. Here we show that our improved cross-sections of this reaction lead to BBN estimates of the baryon density at the 1.6 percent level, in excellent agreement with a recent analysis of the cosmic microwave background7. Improved cross-section data were obtained by exploiting the negligible cosmic-ray background deep underground at the Laboratory for Underground Nuclear Astrophysics (LUNA) of the Laboratori Nazionali del Gran Sasso (Italy)8,9. We bombarded a high-purity deuterium gas target10 with an intense proton beam from the LUNA 400-kilovolt accelerator11 and detected the γ-rays from the nuclear reaction under study with a high-purity germanium detector. Our experimental results settle the most uncertain nuclear physics input to BBN calculations and substantially improve the reliability of using primordial abundances to probe the physics of the early Universe.
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This corrects the article DOI: 10.1103/PhysRevLett.110.192503.
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This corrects the article DOI: 10.1103/PhysRevLett.108.052502.
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In recent years local chiral interactions have been derived and implemented in quantum Monte Carlo methods in order to test to what extent the chiral effective field theory framework impacts our knowledge of few- and many-body systems. In this Letter, we present Green's function Monte Carlo calculations of light nuclei based on the family of local two-body interactions presented by our group in a previous paper in conjunction with chiral three-body interactions fitted to bound- and scattering-state observables in the three-nucleon sector. These interactions include Δ intermediate states in their two-pion-exchange components. We obtain predictions for the energy levels and level ordering of nuclei in the mass range A=4-12, accurate to ≤2% of the binding energy, in very satisfactory agreement with experimental data.
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This corrects the article DOI: 10.1103/PhysRevLett.119.162501.
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The charge and magnetic form factors, F_{C} and F_{M}, respectively, of ^{3}He are extracted in the kinematic range 25 fm^{-2}≤Q^{2}≤61 fm^{-2} from elastic electron scattering by detecting ^{3}He recoil nuclei and scattered electrons in coincidence with the two High Resolution Spectrometers of the Hall A Facility at Jefferson Lab. The measurements find evidence for the existence of a second diffraction minimum for the magnetic form factor at Q^{2}=49.3 fm^{-2} and for the charge form factor at Q^{2}=62.0 fm^{-2}. Both minima are predicted to exist in the Q^{2} range accessible by this Jefferson Lab experiment. The data are in qualitative agreement with theoretical calculations based on realistic interactions and accurate methods to solve the three-body nuclear problem.
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This corrects the article DOI: 10.1103/PhysRevLett.116.102501.
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The astrophysical S factor for the radiative capture d(p,γ)^{3}He in the energy range of interest for big bang nucleosynthesis (BBN) is calculated using an ab initio approach. The nuclear Hamiltonian retains both two- and three-nucleon interactions-the Argonne v_{18} and the Urbana IX, respectively. Both one- and many-body contributions to the nuclear current operator are included. The former retain for the first time, besides the 1/m leading order contribution (m is the nucleon mass), also the next-to-leading order term, proportional to 1/m^{3}. The many-body currents are constructed in order to satisfy the current conservation relation with the adopted Hamiltonian model. The hyperspherical harmonics technique is applied to solve the A=3 bound and scattering states. Particular attention is paid in this second case in order to obtain, in the energy range of BBN, an uncertainty on the astrophysical S factor of the order or below â¼1%. Then, in this energy range, the S factor is found to be â¼10% larger than the currently adopted values. Part of this increase (1%-3%) is due to the 1/m^{3} one-body operator, while the remaining is due to the new more accurate scattering wave functions. We have studied the implication of this new determination for the d(p,γ)^{3}He S factor on the deuterium primordial abundance. We find that the predicted theoretical value for ^{2}H/H is in excellent agreement with its experimental determination, using the most recent determination of the baryon density of the Planck experiment, and with a standard number of relativistic degrees of freedom N_{eff}=3.046 during primordial nucleosynthesis. This calls for a more accurate measurement of the astrophysical S factor in order to confirm the present predictions.
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The charge form factor of 4He has been extracted in the range 29 fm(-2) ≤ Q2 ≤ 77 fm(-2) from elastic electron scattering, detecting 4He recoil nuclei and electrons in coincidence with the high resolution spectrometers of the Hall A Facility of Jefferson Lab. The measurements have uncovered a second diffraction minimum for the form factor, which was predicted in the Q2 range of this experiment. The data are in qualitative agreement with theoretical calculations based on realistic interactions and accurate methods to solve the few-body problem.
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We present a detailed study of the effect of different three-nucleon interactions in p-(3)He elastic scattering at low energies. In particular, two interactions have been considered: one derived from effective field theory at next-to-next-to-leading order and one derived from a more phenomenological point of view-the so-called Illinois model. The four-nucleon scattering observables are calculated by using the Kohn variational principle and the hyperspherical harmonics technique, and the results are compared with available experimental data. We have found that the inclusion of both interactions improves the agreement with the experimental data, in particular, for the proton vector analyzing power.
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To elucidate the physical properties of the force generation mechanism in molecular motors, we have obtained an analytical solution of the bidimensional Fokker-Plank equation which describes a common setup used in single molecule experiments. As a first application of this general result, we have shown that the size of the trapping system affects the dwell time of a multistable particle linearly. A quantitative application to skeletal actomyosin complex, using direct observation of force generation dynamics in the literature, shows that the size of the trapping system used was important for increasing the dwell time of the myosin head stable states to an observable time scale.
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Modelos Químicos , Modelos Moleculares , Modelos Estatísticos , Proteínas Motores Moleculares/química , Proteínas Motores Moleculares/ultraestrutura , Pinças Ópticas , Simulação por Computador , Difusão , Estresse MecânicoRESUMO
The astrophysical S factor for proton-proton weak capture is calculated in chiral effective field theory over the center-of-mass relative-energy range 0-100 keV. The chiral two-nucleon potential derived up to next-to-next-to-next-to leading order is augmented by the full electromagnetic interaction including, beyond Coulomb, two-photon and vacuum-polarization corrections. The low-energy constants entering the weak current operators are fixed so as to reproduce the A=3 binding energies and magnetic moments and the Gamow-Teller matrix element in tritium ß decay. Contributions from S and P partial waves in the incoming two-proton channel are retained. The S factor at zero energy is found to be S(0)=(4.030±0.006)×10(-23) MeV fm(2), with a P-wave contribution of 0.020×10(-23) MeV fm(2). The theoretical uncertainty is due to the fitting procedure of the low-energy constants and to the cutoff dependence.
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The muon-capture reactions {2}H(µ{-},ν{µ})nn and {3}He(µ{-},ν{µ}){3}H are studied with nuclear potentials and charge-changing weak currents, derived in chiral effective field theory. The low-energy constants (LECs) c{D} and c{E}, present in the three-nucleon potential and (c{D}) axial-vector current, are constrained to reproduce the A=3 binding energies and the triton Gamow-Teller matrix element. The muon-capture rates on deuteron and {3}He are predicted to be 399±3 sec{-1} and 1494±21 sec{-1}, respectively. The spread accounts for the cutoff sensitivity, as well as uncertainties in the LECs and electroweak radiative corrections. By comparing the calculated and precisely measured rates on {3}He, a value for the induced pseudoscalar form factor is obtained in good agreement with the chiral perturbation theory prediction.
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A spontaneous rupture of the extensor pollicis longus (EPL) tendon occurred in a patient with trapeziometacarpal arthritis. We hypothesize that a mechanical attrition by protrusion at the trapeziometacarpal joint alone was responsible of a spontaneous rupture of the extensor pollicis longus tendon.
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Artrite/fisiopatologia , Articulações Carpometacarpais/fisiopatologia , Ossos Metacarpais/fisiopatologia , Traumatismos dos Tendões/fisiopatologia , Trapézio/fisiopatologia , Adulto , Artrite/diagnóstico por imagem , Articulações Carpometacarpais/diagnóstico por imagem , Feminino , Humanos , Ossos Metacarpais/diagnóstico por imagem , Radiografia , Ruptura Espontânea/fisiopatologia , Trapézio/diagnóstico por imagemRESUMO
Infertile males sometimes bear structurally balanced chromosome aberrations, such as translocations and inversions, which involve both autosomes and sex chromosomes. The aim of this study was to evaluate genotype-phenotype correlations in a sample of infertile men with various types of Y chromosome abnormalities. In particular, we examined the effect of (i) balanced structural aberrations such as translocations between sex chromosomes and autosomes; (ii) unbalanced structural aberrations such as deletions or isodicentrics, both [idic(Yp)] and [idic(Yq)]. We studied 13 subjects bearing Y chromosome aberrations. Each patient underwent seminal fluid examination, andrological inspection, hormone study, testicular ultrasound, conventional and molecular cytogenetic analysis and study of Y chromosome microdeletions. Comparison of genotype and sperm phenotype in infertile patients with various Y chromosome aberrations revealed the key role of meiotic pairing defects in arresting spermatogenesis, both in the presence and in the absence of azoospermic factor microdeletions and cell mosaicism. The failure of meiosis and, in consequence, spermatogenesis may be a result of the failure to inactivate the X chromosome in the meiotic prophase, which is necessary for normal male spermatogenesis to take place.
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Aberrações Cromossômicas , Cromossomos Humanos Y , Sêmen , Humanos , Hibridização in Situ Fluorescente , Masculino , Reação em Cadeia da PolimeraseRESUMO
In this paper we present a purely mechanical analog of the conventional chemo-mechanical modeling of muscle contraction. We abandon the description of kinetics of the power stroke in terms of jump processes and instead resolve the continuous stochastic evolution on an appropriate energy landscape. In general physical terms, we replace hard spin chemical variables by soft spin variables representing mechanical snap-springs. This allows us to treat the case of small and even disappearing barriers and, more importantly, to incorporate the mechanical representation of the power stroke into the theory of Brownian ratchets. The model provides the simplest non-chemical description for the main stages of the biochemical Lymn-Taylor cycle and may be used as a basis for the artificial micro-mechanical reproduction of the muscle contraction mechanism.