Stabilization of positive coupled differential‐difference equations with unbounded time‐varying delays

This paper researches the static output‐feedback stabilization of single‐input single‐output (SISO) positive coupled differential‐difference equations (CDDEs) with unbounded time‐varying delays. First, a necessary and sufficient condition is provided for the positivity and asymptotical stability of CDDEs with unbounded time‐varying delays. For this type of system, based on the constructed estimates of its solution, a necessary and sufficient condition on asymptotical stability is provided. Then, based on this criterion, for CDDEs with unbounded time‐varying delays, a kind of static output‐feedback controller is designed to ensure the positivity and asymptotical stability of the corresponding closed‐loop systems. It is also worth pointing out that the controller is designed by the linear programming method without parameterization technique. This design approach can also be applied to the static state feedback stabilization problem of CDDEs with unbounded time‐varying delays. Finally, two illustrative examples are given to show the effectiveness of our results.     

Criteria for intensive care unit admission and severity of illness

Intensive care is a specialist area of the hospital with concentration of resources and expertise to look after critically unwell patients. No set criteria exist for admission to intensive care, although patients usually have severe illness associated with physiological dysfunction and actual or impending organ failure. There are multiple scoring systems designed to assess severity of illness, all with significant limitations. The National Early Warning Score 2 (NEWS-2) is a commonly used ‘track and trigger’ system designed to detect and respond to the unwell or deteriorating patient. NEWS-2 is marker of physiological disturbance and high scores correlate with intensive care admission and mortality. Looking at the elective and emergency surgical population, patients at high risk of complications should be admitted to intensive care postoperatively. Increasing age, comorbidities, poor exercise tolerance and major surgical intervention are associated with adverse outcomes. Admission to intensive care often requires difficult time-critical decisions to be made with limited information. Intensive care admission can be the difference between life and death, but there are both physical and psychological harm associated with invasive organ support. The four pillars of medical ethics – autonomy, beneficence, non-maleficence and justice – can be used to guide these decisions.     

Life underneath the VCA umbrella: Perspectives from the US Uterus Transplant Consortium

The parallel emergence of uterus transplantation (UTx) and other transplantation innovations including face and hand transplantation led to the categorization of the uterus as a vascular composite allograft (VCA). With >60 transplants and >20 births worldwide, UTx is transitioning rapidly from a research endeavor to an effective treatment option for women with uterine factor infertility. While it originally made sense to group the innovations under one umbrella, it is time to revisit the designation of UTx as a VCA. We describe how UTx needs unique policy, procedural codes, insurance contracts, and educational initiatives. We contend that separating UTx from VCAs may become necessary in the future to avoid hindering the growth and regulation of this field.     

Hospital‐based health systems 20 years later: A taxonomy for policy research and analysis

ObjectiveBuilding on the original taxonomy of hospital‐based health systems from 20 years ago, we develop a new taxonomy to inform emerging public policy and practice developments.Data SourcesThe 2016 American Hospital Association''s (AHA) Annual Survey; the 2016 IQVIA Healthcare Organizations and Systems (HCOS) database; and the 2017‐2018 National Survey of Healthcare Organizations and Systems (NSHOS).Study DesignCluster analysis of the 2016 AHA Annual Survey data to derive measures of differentiation, centralization, and integration to create categories or types of hospital‐based health systems.Data CollectionPrincipal components factor analysis with varimax rotation generating the factors used in the cluster algorithms.Principal FindingsAmong the four cluster types, 54% (N = 202) of systems are decentralized (−0.35) and relatively less differentiated (−0.37); 23% of systems (N = 85) are highly differentiated (1.28) but relatively decentralized (−0.29); 15% (N = 57) are highly centralized (2.04) and highly differentiated (0.65); and approximately 9 percent (N = 33) are least differentiated (−1.35) and most decentralized (−0.64). Despite differences in calculation, the Highly Centralized, Highly Differentiated System Cluster and the Undifferentiated, Decentralized System Cluster were similar to those identified 20 years ago. The other two system clusters contained similarities as well as differences from those 20 years ago. Overall, 82 percent of the systems remain relatively decentralized suggesting they operate largely as holding companies allowing autonomy to individual hospitals operating within the system.ConclusionsThe new taxonomy of hospital‐based health systems bears similarities as well as differences from 20 years ago. Important applications of the taxonomy for addressing current challenges facing the healthcare system, such as the transition to value‐based payment models, continued consolidation, and the growing importance of the social determinants of health, are highlighted.     

Differences in patient perceptions of integrated care among black,hispanic, and white Medicare beneficiaries

ObjectiveThis study sought to identify potential disparities among racial/ethnic groups in patient perceptions of integrated care (PPIC) and to explore how methodological differences may influence measured disparities.Data SourceData from Medicare beneficiaries who completed the 2015 Medicare Current Beneficiary Survey (MCBS) and were enrolled in Part A benefits for an entire year.Study DesignWe used 4‐point measures of eight dimensions of PPIC and assessed differences in dimensions among racial/ethnic groups. To estimate differences, we applied a “rank and replace” method using multiple regression models in three steps, balancing differences in health status among racial groups and adjusting for differences in socioeconomic status. We reran all analyses with additional SES controls and using standard multiple variable regression.Data Collection/Extraction MethodsNot applicable.Principal FindingsWe found several significant differences in perceived integrated care between Black versus White (three of eight measures) and Hispanic versus White (one of eight) Medicare beneficiaries. On average, Black beneficiaries perceived more integrated support for self‐care than did White beneficiaries (mean difference = 0.14, SE = 0.06, P =.02). Black beneficiaries perceived more integrated specialists’ knowledge of past medical history than did White beneficiaries (mean difference = 0.12, SE = 0.06, P =.01). Black and Hispanic beneficiaries also each reported, on average, 0.18 more integrated medication and home health management than did White beneficiaries (P <.01 and P <.01). These findings were robust to sensitivity analyses and model specifications.ConclusionsThere exist some aspects of care for which Black and Hispanic beneficiaries may perceive greater integrated care than non‐Hispanic White beneficiaries. Further studies should test theories explaining why racial/ethnic groups perceive differences in integrated care.     

Patients' and family members' perspectives on the benefits and working mechanisms of family nursing conversations in Dutch home healthcare

The aim of this study is to propose a model of the benefits and working mechanisms of family nursing conversations in home healthcare from the perspective of participating patients and their family members. Family nursing conversations in this study are intended to optimise family functioning, improve collaboration between family and professional caregivers and ultimately prevent or reduce overburden of family caregivers. In a qualitative grounded theory design, data were collected in 2017 using intensive interviewing with participants of family nursing conversations in home healthcare. A total of 26 participants (9 patients and 17 family members) from 11 families participated in a family nursing conversation and the study. Seven nurses who received extensive education in family nursing conversations conducted them as part of their daily practice. Interviews occurred 4–6 weeks after the family nursing conversation. The model that was constructed in close collaboration with the families consists of three parts. The first part outlines working mechanisms of the conversation itself according to participants, i.e. structured and open communication about the care situation and the presence of all of the people who are involved. The second part consists of the benefits that participants experienced during and immediately after the conversation – an increased sense of overview and improved contact among the people involved – and the related working mechanisms. The last part consists of benefits that emerged in the weeks after the conversation – reduced caregiver burden and improved quality of care – and the related working mechanisms. Insight into the benefits and working mechanisms of family nursing conversations may assist healthcare professionals in their application of the intervention and provides directions for outcomes and processes to include in future studies.     

A Theoretical Model for the Margination of Particles within Blood Vessels

The margination of a particle circulating in the blood stream has been analyzed. The contribution of buoyancy, hemodynamic forces, van der Waals, electrostatic and steric interactions between the circulating particle and the endothelium lining the vasculature has been considered. For practical applications, the contribution of buoyancy, hemodynamic forces and van der Waals interactions should be only taken into account, whilst the effect of electrostatic and steric repulsion becomes important only at very short distances from the endothelium (1–10 nm). The margination speed and the time for margination t_s have been estimated as a function of the density of the particle relative to blood , the Hamaker constant A and radius R of the particle. A critical radius R_c exists for which the margination time t_s has a maximum, which is influenced by both and A: the critical radius decreases as the relative density increases and the Hamaker constant decreases. Therefore, particles used for drug delivery should have a radius smaller than the critical value (in the range of 100 nm) to facilitate margination and interaction with the endothelium. While particles used as nanoharvesting agents in proteomics or genomics analysis should have a radius close to the critical value to minimize margination and increase their circulation time.     

Characteristics of steroid hormone binding systems in hepatocyte plasma membranes

Parameters of binding of cortisone and estradiol to plasma membranes of rat hepatocytes were studied by the method of liquid scintillation radiometry. The presence of two systems for the binding of these hormones in the membranes was demonstrated. One system is specific (saturable) and binds hormones in physiological concentrations. The capacity and affinity of this system for cortisone are significantly higher than for estradiol. The binding parameters within the temperature range from 4 to 37°C for cortisone and estradiol respectively are: Dissociation constant 2.1–3 and 2.7–4.5 nM, number of binding sites 2–2.4 and 0.14–0.18 nmoles/mg protein. Experiments with p-chloromercuribenzoate demonstrate the role of proteins in the working of this system. The second (unsaturable) system is nonspecific and its function is determined by the lipid component of the membranes. The affinity of corticosteroids for hepatocytes is probably due to the activity of the (saturable) specific system of the plasma membranes of these cells.Department of Molecular Pharmacology and Radiobiology, Medico-Biological Faculty, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Yudaev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 89, No. 2, pp. 172–174, February, 1980.     

Cholecystokinin and neurotensin mRNAs are differentially expressed in subnuclei of the ventral tegmental area

Immunohistochemical studies of ventral tegmental area (VTA) neurons indicate that individual cells can contain dopamine as well as the neuropeptide neurotransmitters cholecystokinin (CCK) and neurotensin (NT). We have defined the distribution of the cells expressing the mRNAs encoding these two dopamine cotransmitter peptides in each of the subnuclei of the ventral tegmental area, and quantitated the extent of expression of each gene by using in situ hybridization methods. These studies reveal significant differences in the patterns of expression of each of these two genes within various subdivisions of the VTA. The rostral linear nucleus contained numerous CCK positive cells, some of which appeared to express preproCCK-mRNA at a very high level, but this nucleus contained relatively few NT-expressing cells. The parabrachialis pigmentosus contained numerous NT and CCK positive cells. The paranigralis and interfascicularis nuclei displayed positive CCK cells but with expression at only modest levels. NT cells were very few in these nuclei. The caudal linear nuclei contained the highest number of NT-expressing neurons and these cells expressed very high levels of NT mRNA. The selective distribution of these peptide genes within the VTA subnuclei may have specific consequences. Studies of the connectivity of neurons in the VTA show that the different subnuclei of this region project to several functionally and architectonically different regions of the cerebral cortex and subcortically to nuclei related to the limbic system. Results from our study show very prominent expression of CCK mRNAs in those subnuclei that project heavily to the prefrontal, other cortical areas, and the amygdaloid complex. The NT gene is expressed prominently in those subnuclei of VTA that project heavily to the entorhinal cortex and amygdaloid complex. These results provide support for a differential role for the NT-expressing neurons than that of CCK-expressing neurons of VTA in "reward" mechanisms and in drug-seeking and motivational behavior. These observations could be applied to create working hypotheses and experimental paradigms to test the differential functional activity of the subdivisions of VTA and their potential roles in the pathogenesis and treatment of drug-seeking behavior and other neuropsychiatric disorders.