10,670 research outputs found

    Effect of the curing time on the numerical modelling of the behaviour of a chemically stabilised soft soil

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    The ability of the Modified Cam Clay (MCC) model combined with the Von Mises (VM) model, considering the effect of curing time on the enhancement of the mechanical properties of a chemically stabilised soft soil is examined. The evolution of the strength and stiffness over time is based on the results of undrained compressive strength (UCS) tests carried out for different curing times (from 28 days to 360 days). Initially, the MCC/VM models associated with the effect of curing time are validated by CIU triaxial tests, for curing times of 28 and 90 days. Finally, the behaviour of an embankment built on a soft soil reinforced with deep mixing columns is predicted based on the previously validated models. The results show that the increase of curing time of the DMCs slightly decreases the settlement obtained with a curing time of 28 days

    Corrections to the Boltzmann mean free path in disordered systems with finite size scatterers

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    The mean free path is an essential characteristic length in disordered systems. In microscopic calculations, it is usually approximated by the classical value of the elastic mean free path. It corresponds to the Boltzmann mean free path when only isotropic scattering is considered, but it is different for anisotropic scattering. In this paper, we work out the corrections to the so called Boltzmann mean free path due to multiple scattering effects on finite size scatterers, in the s-wave approximation, ie. when the elastic mean free path is equivalent to the Boltzmann mean free path. The main result is the expression for the mean free path expanded in powers of the perturbative parameter given by the scatterer density.Comment: 12 page

    Accurate free and forced rotational motions of rigid Venus

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    % context :The precise and accurate modelling of a terrestrial planet like Venus is an exciting and challenging topic, all the more interesting since it can be compared with that of the Earth for which such a modelling has already been achieved at the milliarcsecond level % aims: We want to complete a previous study (Cottereau and Souchay, 2009), by determining at the milliarcsecond level the polhody, i.e. the torque-free motion of the axis of angular momentum of a rigid Venus in a body-fixed frame, as well as the nutation of its third axis of figure in space, which is fundamental from an observational point of view. results :In a first part we have computed the polhody, i.e. the respective free rotational motion of the axis of angular momentum of Venus with respect to a body-fixed frame. We have shown that this motion is highly elliptical, with a very long period of 525 cy to be compared with 430 d for the Earth. This is due to the very small dynamical flattening of Venus in comparison with our planet. In a second part we have computed precisely the Oppolzer terms which allow to represent the motion in space of the third Venus figure axis with respect to Venus angular momentum axis, under the influence of the solar gravitational torque. We have determined the corresponding tables of coefficients of nutation of the third figure axis both in longitude and in obliquity due to the Sun, which are of the same order of amplitude as for the Earth. We have shown that the coefficients of nutation for the third figure axis are significantly different from those of the angular momentum axis on the contrary of the Earth. Our analytical results have been validated by a numerical integration which revealed the indirect planetary effects.Comment: 14 pages, 11 figures, accepted for publication in section 11. Celestial mechanics and astrometry of Astronomy and Astrophysics (27/02/2010

    Self-similar dynamics for the modified Korteweg-de Vries equation

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    We prove a local well posedness result for the modified Korteweg-de Vries equa- tion in a critical space designed so that is contains self-similar solutions. As a consequence, we can study the flow of this equation around self-similar solutions: in particular, we give an as- ymptotic description of small solutions as t → +∞ and construct solutions with a prescribed blow up behavior as t → 0

    Access to General Practitioners during the second year of the COVID-19 pandemic in Portugal: a nationwide survey of doctors

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    BackgroundThe Portuguese National Health System (NHS) provides universal coverage and near-free health care, but the population has high out-of-pocket expenses and unmet care needs. This suggests impaired accessibility, a key dimension of primary care. The COVID-19 pandemic has further affected access to health care. Understanding General Practitioners' (GP) experiences during the pandemic is necessary to reconfigure post-pandemic service delivery and to plan for future emergencies. This study aimed to assess accessibility to GPs, from their perspective, evaluating determinants of accessibility during the second pandemic year in Portugal.MethodsAll GPs working in NHS Family Practices in continental Portugal were invited to participate in a survey in 2021. A structured online self-administered anonymous questionnaire was used. Accessibility was assessed through waiting times for consultations and remote contacts and provision of remote access. NHS standards were used to assess waiting times. Descriptive statistics were used to characterize the study sample. Associations between categorical variables were tested using the chi 2 statistic and the Student t-test was used to compare means of continuous variables.ResultsA total of 420 GPs were included (7% of the target population). Median weekly working hours was 49.0 h (interquartile range 42.0-56.8), although only 14% reported a contracted weekly schedule over 40 h. Access to in-person consultations and remote contacts was reported by most GPs to occur within NHS time standards. Younger GPs more often reported waiting times over these standards. Most GPs considered that they do not have enough time for non-urgent consultations or for remote contacts with patients.ConclusionsMost GPs reported compliance with standards for waiting times for most in-person consultations and remote contacts, but they do so at the expense of work overload. A persistent excess of regular and unpaid working hours by GPs needs confirmation. If unpaid overtime is necessary to meet the regular demands of work, then workload and specific allocated tasks warrant review. Future research should focus on younger GPs, as they seem vulnerable to restricted accessibility. GPs' preferences for more in-person care than was feasible during the pandemic must be considered when planning for the post-pandemic reconfiguration of service delivery

    First contact with the health system: a survey study in northern Portugal

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    Objective The objective of this study is to characterise the self-reported first contact with the health system and the reasons stated for each choice, testing associations with population characteristics. Design Cross-sectional survey. Setting Primary care department of a local health unit in northern Portugal. Participants Random sample of 4286 persons, retrieved from all registered adults. Outcomes Participants who stated they usually see the same doctor when a health problem arises were considered to adopt first-contact care and were asked to identify their regular doctor. Participants were asked why they adopt first-contact care or why they choose to do otherwise. Associations between personal characteristics and the adoption of first-contact care were tested using logistic regression. Results There were 808 valid questionnaires received (19% response rate). The mean age of respondents was 53 years, 58% were women and 60% had a high school or higher degree. Most (71%) stated always seeing the same doctor when facing a health problem. This was a general practitioner (GP) in 84%. The main reasons were previous knowledge and trust in the doctor. When this doctor was not a GP, the main reason was the need to obtain an appointment quickly. Participants who chose first-contact care were less likely to have university degrees than those who did not (OR 0.31; 95% CI 0.13 to 0.76). Being registered with the same GP for over 1 year increased the odds of adopting first-contact care: twice as likely for those registered for 1-4 years with the same GP (2.07; 95% CI 1.04 to 4.11), and three times more likely for those registered for over 10 years (3.21; 95% CI 1.70 to 6.08). Conclusions The high adoption of first-contact care and the reasons given for this suggest a strong belief in primary care in this population. The longer patients experience continuity, the more they adopt first-contact care. The preferences of higher-educated patients regarding first-contact care deserve reflection. © Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.Funding text 1: Funding Instituto de Saúde Pública, Universidade do Porto, covered the costs of printing the paper questionnaires. Matosinhos Local Health Unit (National Health Service, Portugal) supported this study by covering the costs of stamped institutional envelopes for sending and returning the questionnaire. This work is financed by national funds through the FCT- Foundation for Science and Technology, I.P., within the scope of projects UIDB/04750/2020 and LA/P/0064/2020

    Asymptotics in Fourier space of self-similar solutions to the modified Korteweg-de Vries equation

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    We give the asymptotics of the Fourier transform of self-similar solutions to the modified Korteweg-de Vries equation, through a fixed point argument in weighted W1,W^{1,\infty} around a carefully chosen, two term ansatz. Such knowledge is crucial in the study of stability properties of the self-similar solutions for the modified Korteweg-de Vries flow. In the defocusing case, the self-similar profiles are solutions to the PainlevéII equation. Although they were extensively studied in physical space, no result to our knowledge describe their behavior in Fourier space. We are able to relate the constants involved in the description in Fourier space with those involved in the description in physical space

    Asymptotics in Fourier space of self-similar solutions to the modified Korteweg-de Vries equation

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    We give the asymptotics of the Fourier transform of self-similar solutions for the modified Korteweg-de Vries equation. In the defocussing case, the self-similar profiles are solutions to the Painlevé II equation; although they were extensively studied in physical space, no result to our knowledge describe their behavior in Fourier space. These Fourier asymptotics are crucial in the study of stability properties of the self-similar solutions for the modified Korteweg-de Vries flow. Our result is obtained through a fixed point argument in a weighted W1,∞ space around a carefully chosen, two term ansatz, and we are able to relate the constants involved in the description in Fourier space with those of the description in physical space

    Diagnosis of monoclonal gammopathy of renal significance

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    Monoclonal gammopathies are a heterogeneous group of disorders characterized by clonal proliferation of immunoglobulin produced by B-lymphocytes or plasma cell clone. The term monoclonal gammopathy of renal significance (MGRS) was introduced to distinguish monoclonal gammopathies that result in the development of kidney disease from those that are benign. Screening for monoclonal immunoglobulin and an appropriate hematologic workup are fundamental and sometimes a difficult challenge, with therapeutic and prognostic implications. Kidney biopsy is essential to determine the exact nature of the lesion and to evaluate the severity of renal disease. In this review we discuss the clinical and pathologic features of MGRS, highlighting the most diagnostic difficulties and current therapeutic options.info:eu-repo/semantics/publishedVersio

    Diagnosis of monoclonal gammopathy of renal significance

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    Monoclonal gammopathies are a heterogeneous group of disorders characterized by clonal proliferation of immunoglobulin produced by B-lymphocytes or plasma cell clone. The term monoclonal gammopathy of renal significance (MGRS) was introduced to distinguish monoclonal gammopathies that result in the development of kidney disease from those that are benign. Screening for monoclonal immunoglobulin and an appropriate hematologic workup are fundamental and sometimes a difficult challenge, with therapeutic and prognostic implications. Kidney biopsy is essential to determine the exact nature of the lesion and to evaluate the severity of renal disease. In this review we discuss the clinical and pathologic features of MGRS, highlighting the most diagnostic difficulties and current therapeutic options.info:eu-repo/semantics/publishedVersio
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