Recent results on the passivity analysis and control of physical systems, based on the balance of dissipated and internally generated energy, are generalised to nonlinear systems represented by bond ...graphs. For linear systems, the internally generated energy associated with modulated sources can be coupled with the dissipative field, so that if external energy sources are excluded, then the system is passive (or dissipative) if the resulting composite multiport field is passive. Such a result for linear systems was previously conveniently expressed in terms of a characteristic matrix being positive semi-definite. Parasitic elements of previous works are no longer required, which allows working on the original bond graph of lower dimension than the augmented bond graph and for no-linear systems avoid inverting the dissipative nonlinear constitutive relations. For nonlinear systems, passivity is now considered through the explicit difference between the dissipated and the internally generated energy. If this energy difference is positive, the system is passive. For control systems, the current work proposes that the controller is designed to have a structure similar to the plant (linear or nonlinear), and its parameters are chosen to assure that in closed-loop the difference between the dissipated and the internally generated energy is positive. In particular, the control parameters can be chosen to assign a desired dissipated energy or to cancel by feedback the internally generated energy and to add damping, therefore achieving sufficient conditions for the passivity of the closed-loop system.
A state feedback is proposed to analyse the stability of a matrix polynomial in closed loop. First, it is shown that a matrix polynomial is stable if and only if a state space realisation of a ladder ...form of certain transfer matrix is stable. Following the ideas of the Routh-Hurwitz stability procedure for scalar polynomials, certain continued-fraction expansions of polynomial matrices are carrying out by unimodular matrices to achieve the Euclid's division algorithm which leads to an extension of the well-known Routh-Hurwitz stability criteria but this time in terms of matrix coefficients. After that, stability of the closed-loop matrix polynomial is guaranteed based on a Corollary of a Lyapunov Theorem. The sufficient stability conditions are: (i) The matrices of one column of the presented array must be symmetric and positive definite and (ii) the matrices of the cascade realisation must satisfy a commutative condition. These stability conditions are also necessary for matrix polynomial of second order. The results are illustrated through examples.
Rheumatoid arthritis (RA) patients commonly report medicinal cannabis use (MCU). Personality has been independently associated with both RA-related outcomes and MCU, but there is no information ...available on how they interact in RA patients. This study aimed to investigate a potential association between personality traits and MCU in RA outpatients, as well as to identify additional factors associated with its use.
This cross-sectional study was performed between June 2020 and August 2021. Consecutive RA outpatients had standardized evaluations using an interview format to collect sociodemographic information, comorbidities, risk of recreational substance use, RA-related disease activity/severity, health-related quality of life, depressive and anxiety symptoms, five personality traits, and MCU in the 12 months before the interview. Multivariable logistic regression estimated adjusted odds ratios (aOR). The study was IRB-approved.
180 patients were included; 160 (88.9%) were women with a mean age of 53.4 ± 13 years. Fifty-three (29.4%) patients reported MCU. Among them, 52 (98.1%) used topical formulations. Neuroticism had the highest overall score (Formula: see text = 3.47 ± 0.34). Openness to experience trait was higher in MCU patients in the comparative analysis (p = 0.007). In the multivariable regression, higher openness trait (aOR: 2.81, 95%CI: 1.11-7.10) along with moderate risk in tobacco use (aOR: 3.36, 95%CI: 1.04-10.7) and higher RA disease activity/severity (aOR: 1.10, 95%CI: 1.01-1.19) were independently associated with MCU.
In the current study, personality influenced the seeking of MCU for pain relief, associating dynamically with higher disease activity/severity and tobacco use. Contrary to other available information, it did not relate to psychopathology or the recreational use of cannabis. Proactive interdisciplinary clinical evaluations around MCU in RA outpatients should include personality, besides standard clinical assessments, to understand patients' motivations for its use as they may reveal important clinical information.
A recent clinical trial demonstrated that a daily dose tenofovir disoproxil fumarate and emtricitabrine (TDF-FTC) can reduce HIV acquisition among men who have sex with men (MSM) and transgender (TG) ...women by 44%, and up to 90% if taken daily. We explored how medical and service providers understand research results and plan to develop clinical protocols to prescribe, support and monitor adherence for patients on PrEP in the United States.
Using referrals from our community collaborators and snowball sampling, we recruited 22 healthcare providers in San Francisco, Oakland, and Los Angeles for in-depth interviews from May-December 2011. The providers included primary care physicians seeing high numbers of MSM and TG women, HIV specialists, community health clinic providers, and public health officials. We analyzed interviews thematically to produce recommendations for setting policy around implementing PrEP. Interview topics included: assessing clinician impressions of PrEP and CDC guidance, considerations of cost, office capacity, dosing schedules, and following patients over time.
Little or no demand for PrEP from patients was reported at the time of the interviews. Providers did not agree on the most appropriate patients for PrEP and believed that current models of care, which do not involve routine frequent office visits, were not well suited for prescribing PrEP. Providers detailed the need to build capacity and were concerned about monitoring side effects and adherence. PrEP was seen as potentially having impact on the epidemic but providers also noted that community education campaigns needed to be tailored to effectively reach specific vulnerable populations.
While PrEP may be a novel and clinically compelling prevention intervention for MSM and TG women, it raises a number of important implementation challenges that would need to be addressed. Nonetheless, most providers expressed optimism that they eventually could prescribe and monitor PrEP in their practice.
The theoretical basis for evaluating shear strength in rock joints is presented and used to derive an equation that governs the relationship between tangential and normal stress on the joint during ...situations of slippage between the joint faces. The dependent variables include geometric dilatancy, the instantaneous friction angle, and a parameter that considers joint surface roughness. The effect roughness is studied, and the aforementioned formula is used to analyse joints under different conditions. A mathematical expression is deduced that explains Barton׳s value for the joint roughness coefficient (JRC) according to the roughness geometry. In particular, when the Hoek and Brown failure criterion is used for a rock in the contact with the surface roughness plane, it is possible to determine the shear strength of the joint as a function of the relationship between the uniaxial compressive strength of the wall with the normal stress acting on the wall. Finally, theoretical results obtained for the geometry of a three-dimensional joint are compared with those of the Barton׳s formulation.
•Theoretical bases allow to elaborate a strength criterion for discontinuities.•A three-dimensional study is performed for joints with spherical cap irregularities.•The theoretical formulation is applied to the Hoek and Brown failure criterion.•Analysis of the results allows the explanation of the Barton empirical formula.
A method for calculating the ultimate bearing capacity at the tip of a pile that is embedded in rock, according to the theory of plasticity, was presented in a previous paper 1 using the original ...Hoek-Brown failure criterion 2, Hoek et al. 3 modified their original model, in order to apply it to highly fractured media (RMR < or = 25), incorporating a new exponent "a" ranging between 0.5 and 0.65. A value of the exponent of a=0.5 corresponds to the original criterion.
The roughness induced during glow-discharge optical-emission spectroscopy (GDOES) measurements has been reported to cause a loss of resolution during GDOES depth-profiling analysis. In this paper, we ...undertake for the first time a study of the dynamics of the surface morphology of chromium and titanium thin films (designed in mono and multilayer structures) under the impinging of GDOES incoming ions. We performed this study under the theoretical framework of the dynamic scaling theory, by analysing surface morphology changes, as measured ex-situ by AFM, with irradiation time. For single metal layers it was found that, after an initial surface smoothening, the surface undergoes a rapid steep roughening for both systems, with quite similar quantitative dynamics. Once this roughening ends a second temporal scaling regime arises, operating for long length scales with dynamics depending on the sputtering rate of the material. For the chromium layer, with a very high sputtering rate of 5.5 μm min
−1
, this regime is consistent with the KPZ model, whereas for the titanium layer an EW scaling regime is indicated. These different scaling regimes are consistent with the development of larger surface slopes for the Cr system. In the multilayer systems, the initial roughness induced on the top Cr layer by GDOES has similar dynamics to that for single-layer Cr. However, a clear decrease in the roughness was observed once the underlying Ti layer, with a lower sputtering rate, was reached. This decrease in the induced roughness is maintained while the Ti layer is eroded. Therefore, choice of appropriate material (i.e. sputtering yield values) combinations and of their depth of location can enable tuning of GDOES-induced roughness and achieve substantial control over the depth profiling process.
In the winter of 1714–1715, a large rotational landslide originated on the northern slope of the Sierra de Aralar (Navarra, Spain), generating an earthflow that slowly descended through the valley ...for a kilometer and a half destroying the village of Inza. An interdisciplinary research recreated the historical process of the event and the geomorphological characterization of this large landslide. The geological analysis and hydrogeological characteristics of the site also identified the determining factors of this historical event. From the analysis that triggered the landslide and how the climate affected events can now be demonstrated from historical records of excess rainfall and the initial start of the process. From the recreated pre-failure topography, the stability of the original slope was studied using a 3D numerical model to identify the factors, causes and mechanism that controlled the development of the landslide.
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