Rewriting Modulo Traced Comonoid Structure

In this paper we adapt previous work on rewriting string diagrams using hypergraphs to the case where the underlying category has a traced comonoid structure, in which wires can be forked and the outputs of a morphism can be connected to its input. Such a structure is particularly interesting because any traced Cartesian (dataflow) category has an underlying traced comonoid structure. We show that certain subclasses of hypergraphs are fully complete for traced comonoid categories: that is to say, every term in such a category has a unique corresponding hypergraph up to isomorphism, and from every hypergraph with the desired properties, a unique term in the category can be retrieved up to the axioms of traced comonoid categories. We also show how the framework of double pushout rewriting (DPO) can be adapted for traced comonoid categories by characterising the valid pushout complements for rewriting in our setting. We conclude by presenting a case study in the form of recent work on an equational theory for sequential circuits: circuits built from primitive logic gates with delay and feedback. The graph rewriting framework allows for the definition of an operational semantics for sequential circuits

A compositional theory of digital circuits

A theory is compositional if complex components can be constructed out of simpler ones on the basis of their interfaces, without inspecting their internals. Digital circuits, despite being studied for nearly a century and used at scale for about half that time, have until recently evaded a fully compositional theoretical understanding. The sticking point has been the need to avoid feedback loops that bypass memory elements, the so called 'combinational feedback' problem. This requires examining the internal structure of a circuit, defeating compositionality. Recent work remedied this theoretical shortcoming by showing how digital circuits can be presented compositionally as morphisms in a freely generated Cartesian traced (or dataflow) category. The focus was to support a better syntactical understanding of digital circuits, culminating in the formulation of novel operational semantics for digital circuits. In this paper we shift the focus onto the denotational theory of such circuits, interpreting them as functions on streams with to certain properties. These ensure that the model is fully abstract, i.e. the equational theory and the semantic model are in perfect agreement. To support this result we introduce two key equations: the first can reduce circuits with combinational feedback to circuits without combinational feedback via finite unfoldings of the loop, and the second can translate between open circuits with the same behaviour syntactically by reducing the problem to checking a finite number of closed circuits. The most important consequence of this new semantics is that we can now give a recipe that ensures a circuit always produces observable output, thus using the denotational model to inform and improve the operational semantics.Comment: Restructured and refined presentation, 21 page

Factors that predict fertility desires for people living with HIV infection at a support and treatment centre in Kabale, Uganda

<p>Abstract</p> <p>Background</p> <p>Studies from different contexts worldwide indicate that HIV positive patients manifest high-risk sexual behavior characterized by fertility intentions, multiple sexual partners, non-use of contraceptives and non-disclosure of HIV status to their sex partners. The objective was to analyze fertility desires among persons living with HIV at a treatment centre in Kabale Hospital, Southwestern Uganda.</p> <p>Methods</p> <p>From January to August 2009, we interviewed 400 HIV positive patients seeking care using an interviewer-administered questionnaire. We assessed socio-demographic variables, reproductive history, sexuality and fertility desires. At bivariate and multivariate analysis, characteristics of participants who reported or did not report desire to have a child in the near future were compared.</p> <p>Results</p> <p>Of the 400 respondents, (25.3%) were male, 47.3% were aged 25-34 years, over 85% were currently married or had ever been married, and the 62% had primary level of education or less. Over 17% had produced a child since the HIV diagnosis was made, and 28.6% reported that they would like to have a child in the near future. Age of the respondent, being single (versus being ever-married) and whether any of the respondents' children had died were inversely associated with fertility intentions.</p> <p>Conclusion</p> <p>Factors inversely associated with fertility intentions were age of the respondent, marital status and whether any of the respondents' children had died. Use of antiretroviral therapy was not associated with fertility intentions.</p

Alien Physicians and Their Admission into the United States

This Article discusses legislation passed by Congress in 1976 to drastically reduce the eligibility of alien physicians to enter the United States because of a fear of inferior medical services and a belief that such immigration was leading to a shortage of health care providers in some foreign nations. The article surveys the new requirements such as passing both medical and English competence examinations as well as obtaining individual labor certifications. The article goes on to discuss ways in which alien physicians can come to the Unites States without passing these examinations

Landscape-Scale Dynamics of Aspen in Rocky Mountain National Park, Colorado

Past studies of quaking aspen in Rocky Mountain National Park suggested that the aspen population is declining due to intensive browsing by elk (Cervus elaphus). These studies were conducted in the elk winter range, an area of intensive elk impact. The elk summer range experiences less intense grazing pressure. We tested the hypothesis that impacts of elk would be greater in the elk winter range than the summer range with landscape-scale data from the Park. The detrimental effects of elk on aspen are highly localized and, at larger spatial scales, elk browsing does not seem to be influencing the aspen population

Conjunctival-corneal melt in association with carotid artery stenosis

Rosalind MK Stewart1, Say Aun Quah1, Dan Q Nguyen2, Stephen B Kaye11Royal Liverpool University Hospital, Liverpool, UK; 2Bristol Eye Hospital, Bristol, UKPurpose: To report a case of severe conjunctival-corneal melt in association with carotid artery stenosis.Methods: Observational case report.Results: A 76-year-old man with a history of bilateral severe carotid artery occlusion and nonarteritic ischemic optic neuropathy developed a spontaneous bulbar conjunctival defect. Despite intensive lubrication, and attempts at surgical closure including an amniotic membrane patch graft, it progressed with subsequent adjacent corneal perforation. Thorough investigations revealed no underlying disease, except markedly delayed episcleral vessel filling on anterior segment fluorescein angiography.Conclusions: Neovascularisation is a known factor in the inhibition of ulceration. In light of the findings in this report, ocular ischemia should be considered as a cause or contributing factor in the differential diagnosis of conjunctival-corneal melt.Keywords: conjunctival melt, corneal melt, ocular ischemia, carotid artery stenosi

Prevalence and predictors of unknown HIV status among women delivering in Mulago National Referral Hospital, Kampala, Uganda.

Introduction: Knowledge of a person’s HIV status during pregnancy is critical for prevention of mother to child transmission of HIV.Objectives: To determine the prevalence and factors associated with unknown HIV status among women delivering in Mulago Hospital.Methods: This was a cross-sectional study of women that had just delivered. The women’s demographic characteristics, health seeking behaviour, health system-related factors and knowledge on PMTCT were collected. Fisher’s exact test, Wilcoxon rank sum test and logistic regression were used to test associations.Results: The prevalence of unknown HIV status was 2.6% (10/382). Attending ANC at higher level facilities (OR =0.1 95% CI 0.0 – 0.4) and having been counselled for HIV testing during ANC (OR=0.1, 95% CI 0.0 - 0.4) were associated with likelihood of having a known HIV status. Out of the ten women with unknown HIV status, 4/6 who attended ANC in public/ government accredited health facilities “opted out” of HIV testing due to personal reasons. Among the four who attended ANC in private clinics, two were not offered HIV testing and one “opted out”.Conclusion: Most participants had a known HIV status at labour (97%). Private clinics need to be supported to provide free quality HCT services in ANC.Keywords: Unknown HIV status, women delivering, Mulago National Referral Hospital, Kampala, Ugand

Experiences of referral with an obstetric emergency : voices of women admitted at Mbarara Regional Referral Hospital, South Western Uganda

Funding Information: The research reported in this publication was supported by the Staff Capacity Development Scheme/ fund of Mbarara University of Science and Technology which supports staff education. Publisher Copyright: © 2023, The Author(s).Background: Life-threatening obstetric complications usually lead to the need for referral and constitute the commonest direct causes of maternal deaths. Urgent management of referrals can potentially lower the maternal mortality rate. We explored the experiences of women referred with obstetric emergencies to Mbarara Regional Referral Hospital (MRRH) in Uganda, in order to identify barriers and facilitating factors. Methods: This was an exploratory qualitative study. In-depth interviews (IDIs) were conducted with 10 postnatal women and 2 attendants as key informants. We explored health system and client related factors to understand how these could have facilitated or hindered the referral process. Data was analyzed deductively employing the constructs of the Andersen Healthcare Utilization model. Results: Women experienced transport, care delays and inhumane treatment from health care providers (HCPs). The obstetric indications for referral were severe obstructed labor, ruptured uterus, and transverse lie in advanced labor, eclampsia and retained second twin with intrapartum hemorrhage. The secondary reasons for referral included; non-functional operating theatres due to power outages, unsterilized caesarian section instruments, no blood transfusion services, stock outs of emergency drugs, and absenteeism of HCPs to perform surgery. Four (4) themes emerged; enablers, barriers to referral, poor quality of care and poor health facility organization. Most referring health facilities were within a 30–50 km radius from MRRH. Delays to receive emergency obstetric care (EMOC) led to acquisition of in-hospital complications and eventual prolonged hospitalization. Enablers to referral were social support, financial preparation for birth and birth companion’s knowledge of danger signs. Conclusion: The experience of obstetric referral for women was largely unpleasant due to delays and poor quality of care which contributed to perinatal mortality and maternal morbidities. Training HCPs in respectful maternity care (RMC) may improve quality of care and foster positive postnatal client experiences. Refresher sessions on obstetric referral procedures for HCPs are suggested. Interventions to improve the functionality of the obstetric referral pathway for rural south-western Uganda should be explored.Peer reviewe