Qualitative Criterion for Interception in a Pursuit/Evasion Game

A qualitative account is given of a differential pursuit/evasion game. A criterion for the existence of an intercept solution is obtained using future cones that contain all attainable trajectories of target or interceptor originating from an initial position. A sufficient and necessary conditon that an opportunity to intercept always exist is that, after some initial time, the future cone of the target be contained within the future cone of the interceptor. The sufficient condition may be regarded as a kind of Nash equillibrium.Comment: 8 pages; revsions and corrigend

Missing and Murdered Indigenous Women (MMIW): Bringing Awareness through the Power of Student Activism

Students are often an underutilized resource for advocacy and activism. Students have a unique positionality as members of academia who greatly understand the power and privilege higher education can bring- particularly when they have intersectional identities as women, minorities, and members of marginalized groups. This article tells the stories of two such Native American women who are using their power and privilege as it intersects with lived experience to bring awareness to the epidemic of Missing and Murdered Indigenous Women (MMIW). The article brings light to what drives them to promote social justice movements and how they work to institute positive change. Through their experiences, they share suggestions for how advanced professionals and professional organizations can aid students in engaging in social justice movements through empowerment, connection, and support. With students as the feet on the ground and the voice for the voiceless, we hope to promote awareness of MMIW and institute lasting change to protect our Native American women and girls

Hyperreactio luteinalis: benign disorder masquerading as an ovarian malignancy

Hyperreactio luteinalis (HL) refers to pregnancy related moderate to marked enlargement of the ovaries due to multiple benign theca lutein cysts. It is caused due to elevated Human chorionic gonadotropins leading to maternal complications such as preeclampsia and preterm delivery may result. We report case of a 24 years old lady, G3P1A1L1 with spontaneous twin pregnancy at 13 weeks + 4 days gestation presented with chief complaint of lower abdominal pain on exertion for 5 days. Ultrasonography (USG) showed a large left ovarian mass in Pouch of Douglas pushing uterus up and extending into the left side of midline upto costal cartilage. It showed multiple thick septations with vascularity pointing towards malignancy. CA-125 was elevated to 193U/ml. Laparotomy was undertaken. Intraoperatively, bilateral huge, congested, bosselated, multicystic ovarian masses were present which replaced normal ovaries and appeared malignant. Bilateral oophorectomy was done. Specimens received for histopathological examination comprised of two large multilobulated, dark brown, ovarian masses with intact glistening capsule. Serial sections through both the masses showed thin walled, multiloculated cysts with smooth inner lining, filled with thin clear to hemorrhagic fluid. On microscopic examination diagnosis of Hyperreactio luteinalis, bilateral ovarian masses were made. HL can be misinterpreted on USG or laparotomy as ovarian malignancy resulting in unnecessary surgical intervention

Dehydration-Induced Loss of Corrosion Protection Properties in Chromate Conversion Coatings on Aluminum Alloy 2024-T3

It is well known that chromate conversion coatings (CCCs) exhibit a prompt loss in corrosion resistance when exposed to moderately elevated temperatures (60-100°C). They also suffer a gradual loss in corrosion resistance due to ambient temperature exposure. To better understand the origins of losses in corrosion resistance, CCCs were formed on 99.99% Al, 1100 Al [Al-1.0(Fe, Si, Cu)], and 2024-T3 (Al-4.4Cu-1.5Mg-0.6Mn), exposed to elevated and ambient temperature exposures for various lengths of time, and characterized using several different methods. The Cr(VI):total Cr ratio in CCCs was estimated by analysis of data derived from X-ray absorption spectroscopy. Corrosion resistance was measured by electrochemical impedance spectroscopy. The evolution of shrinkage cracking was examined by environmental scanning electron microscopy. Cr(VI) leaching experiments were also carried out to characterize the effect of thermal exposure on Cr(VI) release. Thermal analysis and X-ray diffraction were conducted to characterize the temperature-dependent changes in CCCs. Results show that CCCs degrade in several distinct steps over the temperature range of 20 to 500°C. Our findings support the longstanding notion that dehydration is the root cause for losses in corrosion resistance due to aging at ambient and low temperatures (<150°C). Extended X-ray fine structure measurements indicate a shortening in Cr(III)-Cr(III) nearest neighbor distances upon dehydration. This is interpreted as a consolidation in the Cr(OH)_3 backbone of the CCC which leads to shrinkage cracking and immobilization of Cr(VI). This finding is important because it links older observations of the effects of aging and heating on CCCs to newer interpretations of CCC formation based on inorganic polymerization. Overall, these results reveal CCCs to be highly dynamic coatings with corrosion resistance properties that vary considerably in both the short term and long term

Overt hypoadrenalism is uncommon in patients with stage 3 and 4 bronchogenic carcinoma

Introduction. Lung cancer is the leading cause of cancer mortality in most countries. The adrenal glands are common sites of metastatic lung cancer as approximately 40% of subjects with stage 4 bronchogenic carcinoma have adrenal metastases. The prevalence of biochemical hypoadrenalism is, however, remarkably poorly documented.Objectives. Our study aimed to determine the prevalence of primary hypoadrenalism, as defined by a subnormal cortisol response to the 250 µg adrenocorticotrophic hormone (ACTH) stimulation test, in patients with stage 3 and 4 lung cancer.Methods. Thirty patients with stage 3 and 4 bronchogenic carcinoma were prospectively recruited from the bronchus clinic. Demographic data and electrolytes were recorded and each patient had a 250 µg ACTH stimulation test to determine the prevalence of overt adrenal insufficiency, defined as a +30 minute cortisol of less than 550 nmol/l.Results. The median age and quartile deviation was 62 (10) years and the median basal cortisol was 429.5 (321) nmol/l. The median peak cortisol was 828.5 (342) nmol/l (range 536 - 1 675 nmol/l). Twenty-eight patients (93.3%) had an appropriate rise of cortisol to greater than 550 nmol/l following 250 µg ACTH stimulation. Two patients (6.7%) had mild primary adrenal failure with a peak cortisol between 500 and 550 nmol/l associated with a raised plasma ACTH concentration (131.4 and 10.5 pmol/l, normal 2.2 - 10 pmol/l). Twenty-eight patients (92.9%) were normonatraemic, while the two hyponatraemic patients had biochemical evidence of the syndrome of inappropriate antidiuretic hormone secretion.Conclusion. In conclusion, despite evidence that the adrenal glands of patients with disseminated bronchogenic carcinoma are frequently affected by metastatic disease, biochemical evidence of clinically significant hypoadrenalism is relatively uncommon and is not accurately predicted by electrolyte abnormalities

Discrete complex analysis on planar quad-graphs

We develop a linear theory of discrete complex analysis on general quad-graphs, continuing and extending previous work of Duffin, Mercat, Kenyon, Chelkak and Smirnov on discrete complex analysis on rhombic quad-graphs. Our approach based on the medial graph yields more instructive proofs of discrete analogs of several classical theorems and even new results. We provide discrete counterparts of fundamental concepts in complex analysis such as holomorphic functions, derivatives, the Laplacian, and exterior calculus. Also, we discuss discrete versions of important basic theorems such as Green's identities and Cauchy's integral formulae. For the first time, we discretize Green's first identity and Cauchy's integral formula for the derivative of a holomorphic function. In this paper, we focus on planar quad-graphs, but we would like to mention that many notions and theorems can be adapted to discrete Riemann surfaces in a straightforward way. In the case of planar parallelogram-graphs with bounded interior angles and bounded ratio of side lengths, we construct a discrete Green's function and discrete Cauchy's kernels with asymptotics comparable to the smooth case. Further restricting to the integer lattice of a two-dimensional skew coordinate system yields appropriate discrete Cauchy's integral formulae for higher order derivatives.Comment: 49 pages, 8 figure

Formation of Chromate Conversion Coatings on Aluminum and Its Alloys

In situ X-ray adsorption near-edge structure (XANES) has been used to investigate the formation of chromate conversion coatings on pure Al, commercial Al alloys (AA 1100, AA2024, and AA7075), and a series of binary Al–Cu alloys. The method employed cells designed to determine the growth of the total chromium [Cr(total)] and hexavalent chromate [Cr(VI)] in the chromate conversion coating (CCC) as a function of exposure time to a chromate solution. Three sets of data were obtained, where (i) the Al was exposed to only a limited amount of solution; (ii) the chromate solution was excluded after short periods of repeated exposures to the solution; and (iii) the Al was exposed continuously to the chromate solution. All the results showed a very rapid initial growth within the first seconds, followed by a continued increase in thickness for exposures up to 1 h. Measurements with Al–Cu binary alloys demonstrated that the difference observed in AA2024 and AA1100 may not be due to Cu alloying. The proportion of Cr(VI) in the coatings becomes approximately constant after 180 s of exposure for all the specimens examined, even though the coatings continued to grow

Advanced XPS characterization: XPS-based multi-technique analyses for comprehensive understanding of functional materials

X-ray photoelectron spectroscopy (XPS) has achieved maturity as an analytical technique in that it is a ubiquitous tool in the materials community, however as made apparent by recent reviews highlighting it's misuse as a means of chemical deduction, it is a practice which is greatly misunderstood even in its simplest form. Advanced XPS techniques, or a combination of XPS and a complementary surficial probe may elicit auxiliary information outside of the scope of the standard sphere of appreciation. This review aims to bring to the attention of the general materials audience a landscape of some atypical applications of lab-based XPS and combinatorial approaches of related surface analysis, such as ion scattering, ultraviolet photoelectron, electron energy loss and auger emission spectroscopies found on many lab-based instrument set-ups

An assessment of organisational values culture and performance in Cape Town's primary healthcare services

Objectives: Improving the quality of primary health care in South Africa is a national priority and the Western Cape Department of Health has identified staff and patient experience as a key component. Its strategic plan, Vision 2020, espouses caring, competence, accountability, integrity, responsiveness and respect as the most important organisational values. This study aimed to measure the personal values of staff, as well as current and desired organisational values. Design: A cross-sectional survey used the cultural values assessment tool. Data were analysed by the Barrett Value Centre. Setting and subjects: Staff and managers at five community health centres in the Cape Town Metropole. Outcome measures: Personal values, current and desired organisational values, organisational entropy and organisational scorecard. Results: In total, 154 staff members completed the survey. Participants reported personal values that are congruent with a move towards more patient-centred care. The top 10 current organisational values were not sharing information, cost reduction, community involvement, confusion, control, manipulation, blame, power, results orientation, hierarchy, long hours and teamwork. Desired organisational values were open communication, shared decision-making, accountability, staff recognition, leadership development and professionalism. Organisational entropy was high at 36% of all values. Only teamwork and community involvement were found in both the current and desired culture. The organisational scorecard showed a lack of current focus on finances, evolution and patient experience. Conclusion: The organisational culture of the Metro District Health Services is currently not well aligned with the values expressed in Vision 2020, and the goal of delivering patient-centred care