Backstepping PDE Design: A Convex Optimization Approach

Abstract\u2014Backstepping design for boundary linear PDE is formulated as a convex optimization problem. Some classes of parabolic PDEs and a first-order hyperbolic PDE are studied, with particular attention to non-strict feedback structures. Based on the compactness of the Volterra and Fredholm-type operators involved, their Kernels are approximated via polynomial functions. The resulting Kernel-PDEs are optimized using Sumof- Squares (SOS) decomposition and solved via semidefinite programming, with sufficient precision to guarantee the stability of the system in the L2-norm. This formulation allows optimizing extra degrees of freedom where the Kernel-PDEs are included as constraints. Uniqueness and invertibility of the Fredholm-type transformation are proved for polynomial Kernels in the space of continuous functions. The effectiveness and limitations of the approach proposed are illustrated by numerical solutions of some Kernel-PDEs

Design and construction of a point-contact spectroscopy rig with lateral scanning capability

The design and realization of a cryogenic rig for point-contact spectroscopy measurements in the needle-anvil configuration is presented. Thanks to the use of two piezoelectric nano-positioners, the tip can move along the vertical ($z$) and horizontal ($x$) direction and thus the rig is suitable to probe different regions of a sample \textit{in situ}. Moreover, it can also form double point-contacts on different facets of a single crystal for achieving, e.g., an interferometer configuration for phase-sensitive measurements. For the latter purpose, the sample holder can also host a Helmholtz coil for applying a small transverse magnetic field to the junction. A semi-rigid coaxial cable can be easily added for studying the behavior of Josephson junctions under microwave irradiation. The rig can be detached from the probe and thus used with different cryostats. The performance of this new probe has been tested in a Quantum Design PPMS system by conducting point-contact Andreev reflection measurements on Nb thin films over large areas as a function of temperature and magnetic field.Comment: 7 pages, 7 figures, published in Rev. Sci. Instru

Encapsulación de lacasa en alginato: comparación entre extrusión asistida y no asistida para producción a gran escala

ResumenSe estudió el efecto de la extrusión asistida y no asistida para la producción a gran escala sobre el tamaño, forma y desempeño bioquímico de capsulas de lacasa-alginato. Las capsulas se formularon usando una concentración de alginato al 1.0% y 3.0% (m/v) y se prepararon por un método de extrusión-goteo. Los resultados mostraron que la técnica de extrusión afecta el tamaño de las capsulas y su distribución de tamaño, pero no afecta su forma. La caracterización bioquímica mostro un comportamiento similar entre ambos métodos de extrusión. Sin embargo, las capsulas no asistidas presentaron mayor variabilidad en su actividad enzimática y menor estabilidad en el tiempo. Los resultados muestran que con el método de extrusión, material particulado altamente homogéneo mejora bioprocesos facilitando el control de etapas de temperatura y pH, por lo tanto, un método asistido presenta varias ventajas para la producción de material particulado de lacasa en grandes cantidades. AbstractThe effect of assisted and not-assisted extrusion for large scale production on size, shape and biochemical performance of the laccase-alginate beads was studied. The alginate beads were formulated using 1.0% and 3.0% (w/v) alginate concentrations and were prepared by an extrusion-dripping method. Results showed that the extruding technique affects the beads size and size distribution but not the beads shape. The biochemical characterization showed a similar performance for both extruding methods. However, not-assisted beads presented higher enzymatic activity variability and lower stability in time. Results shown that in extrusion method, bioprocesses are improved by highly homogeneous particulate material easing temperature or pH controlled steps, then, an assisted method presents several benefits for producing laccase particulate material at large quantities

Development and Validity Assessment of a Chronic Obstructive Pulmonary Disease Knowledge Questionnaire in Low- and Middle-Income Countries

Rationale: The majority of the morbidity and mortality related to chronic obstructive pulmonary disease (COPD) occurs in low- and middle-income countries (LMICs). Despite the increasing burden of COPD, disease-specific knowledge among healthcare workers (HCWs) and patients in LMICs remains limited. COPD knowledge questionnaires are valid and reliable tools to assess COPD knowledge and can be employed in settings with limited health literacy. Objective: To develop and assess validity and reliability of a COPD knowledge questionnaire among individuals with COPD in three LMIC settings. Methods: Twelve questions were generated by an expert team of sixteen researchers, physicians, and public health professionals to create an LMIC-specific COPD knowledge questionnaire. Content was based on previous instruments, clinical guidelines, focus group discussions, and questionnaire piloting. Participants with COPD completed the questionnaire across three diverse LMIC settings before and three months after delivery of a standardized COPD specific education package by a local community health worker (CHW) trained to deliver the education to an appropriate standard. We utilized paired t-tests to assess improvement in knowledge post-intervention. Results: Questionnaire development initially yielded 52 items. Based on community feedback and expertise, items were eliminated and added yielding a final 12-item questionnaire, with a maximum total score of 12. A total of 196 participants with COPD were included this study in Nepal (n=86), Peru (n=35) and Uganda (n=75). Mean (± SD) baseline score was 8.0 ± 2.5 and 3-months post-education the mean score was 10.2 ± 1.7 among participants. The CHW-led COPD educational intervention improved COPD knowledge among community members by 2.2 points (95% CI 1.8 to 2.6, t=10.9, p<0.001). Internal consistency using Cronbach’s alpha was 0.75. Conclusion: The LMIC COPD-KQ demonstrates face and content validity and acceptable internal consistency through development phases, suggesting a reliable and valid COPD education instrument that can be utilized to assess educational interventions across LMIC settings. Clinical trial registered with ClinicalTrials.gov (NCT03365713

Controlled synthesis of Zn 0 nanoparticles by bioreduction

Abstract Synthesis of metallic Zn nanoparticles through bio-reduction methods is reported for the first time. The structure, shape and size of the nanoparticles are critically controlled through the pH used in the sample preparation. High resolution electron microscopy was used in order to determine the structure of individual nanoparticles. Formation of quantum dots and the efficiency of ion reduction in the synthesis process are studied through the optical absorption in colloids. The structure and stability of the Zn clusters (up to 4000 atoms) were determined through the calculation of minimum energy configurations using molecular and quantum mechanics approximations and image simulation. The structure of the obtained nanoparticles was preferentially hexagonal, although multiple twinned and fcc-like structures were identified. The size controlled synthesis of small nanoparticles in the quantum-dot range was demonstrated successfully

Evaluation of the Performance of Routine Information System Management (PRISM) framework: evidence from Uganda

<p>Abstract</p> <p>Background</p> <p>Sound policy, resource allocation and day-to-day management decisions in the health sector require timely information from routine health information systems (RHIS). In most low- and middle-income countries, the RHIS is viewed as being inadequate in providing quality data and continuous information that can be used to help improve health system performance. In addition, there is limited evidence on the effectiveness of RHIS strengthening interventions in improving data quality and use. The purpose of this study is to evaluate the usefulness of the newly developed Performance of Routine Information System Management (PRISM) framework, which consists of a conceptual framework and associated data collection and analysis tools to assess, design, strengthen and evaluate RHIS. The specific objectives of the study are: a) to assess the reliability and validity of the PRISM instruments and b) to assess the validity of the PRISM conceptual framework.</p> <p>Methods</p> <p>Facility- and worker-level data were collected from 110 health care facilities in twelve districts in Uganda in 2004 and 2007 using records reviews, structured interviews and self-administered questionnaires. The analysis procedures include Cronbach's alpha to assess internal consistency of selected instruments, test-retest analysis to assess the reliability and sensitivity of the instruments, and bivariate and multivariate statistical techniques to assess validity of the PRISM instruments and conceptual framework.</p> <p>Results</p> <p>Cronbach's alpha analysis suggests high reliability (0.7 or greater) for the indices measuring a promotion of a culture of information, RHIS tasks self-efficacy and motivation. The study results also suggest that a promotion of a culture of information influences RHIS tasks self-efficacy, RHIS tasks competence and motivation, and that self-efficacy and the presence of RHIS staff have a direct influence on the use of RHIS information, a key aspect of RHIS performance.</p> <p>Conclusions</p> <p>The study results provide some empirical support for the reliability and validity of the PRISM instruments and the validity of the PRISM conceptual framework, suggesting that the PRISM approach can be effectively used by RHIS policy makers and practitioners to assess the RHIS and evaluate RHIS strengthening interventions. However, additional studies with larger sample sizes are needed to further investigate the value of the PRISM instruments in exploring the linkages between RHIS data quality and use, and health systems performance.</p

Chemical analysis of pottery demonstrates prehistoric origin for high-altitude alpine dairying

The European high Alps are internationally renowned for their dairy produce, which are of huge cultural and economic significance to the region. Although the recent history of alpine dairying has been well studied, virtually nothing is known regarding the origins of this practice. This is due to poor preservation of high altitude archaeological sites and the ephemeral nature of transhumance economic practices. Archaeologists have suggested that stone structures that appear around 3,000 years ago are associated with more intense seasonal occupation of the high Alps and perhaps the establishment of new economic strategies. Here, we report on organic residue analysis of small fragments of pottery sherds that are occasionally preserved both at these sites and earlier prehistoric rock-shelters. Based mainly on isotopic criteria, dairy lipids could only be identified on ceramics from the stone structures, which date to the Iron Age (ca. 3,000 - 2,500 BP), providing the earliest evidence of this practice in the high Alps. Dairy production in such a marginal environment implies a high degree of risk even by today’s standards. We postulate that this practice was driven by population increase and climate deterioration that put pressure on lowland agropastoral systems and the establishment of more extensive trade networks, leading to greater demand for highly nutritious and transportable dairy products