"Almost-stable" matchings in the Hospitals / Residents problem with Couples

The Hospitals / Residents problem with Couples (hrc) models the allocation of intending junior doctors to hospitals where couples are allowed to submit joint preference lists over pairs of (typically geographically close) hospitals. It is known that a stable matching need not exist, so we consider min bp hrc, the problem of finding a matching that admits the minimum number of blocking pairs (i.e., is “as stable as possible”). We show that this problem is NP-hard and difficult to approximate even in the highly restricted case that each couple finds only one hospital pair acceptable. However if we further assume that the preference list of each single resident and hospital is of length at most 2, we give a polynomial-time algorithm for this case. We then present the first Integer Programming (IP) and Constraint Programming (CP) models for min bp hrc. Finally, we discuss an empirical evaluation of these models applied to randomly-generated instances of min bp hrc. We find that on average, the CP model is about 1.15 times faster than the IP model, and when presolving is applied to the CP model, it is on average 8.14 times faster. We further observe that the number of blocking pairs admitted by a solution is very small, i.e., usually at most 1, and never more than 2, for the (28,000) instances considered

Profits, Costs, and the Changing Structure of Dairy Farming

U.S. dairy production is consolidating into fewer but larger farms. This report uses data from several USDA surveys to detail that consolidation and to analyze the financial drivers of consolidation. Specifically, larger farms realize lower production costs. Although small dairy farms realize higher revenue per hundredweight of milk sold, the cost advantages of larger size allow large farms to be profitable, on average, even while most small farms are unable to earn enough to replace their capital. Further survey evidence, as well as the financial data, suggest that consolidation is likely to continue.Dairy farming, economies of scale, economies of size, dairy farm structure, milk costs, Farm Management, Industrial Organization, Livestock Production/Industries,

Multiple myeloma presenting with high-output heart failure and improving with anti-angiogenesis therapy: two case reports and a review of the literature

<p>Abstract</p> <p>Introduction</p> <p>Common manifestations of multiple myeloma include osteolytic lesions, cytopenias, hypercalcemia, and renal insufficiency. Patients may also exhibit heart failure which is often associated with either past therapy or cardiac amyloidosis. A less recognized mechanism is high-output heart failure. Diuretic therapy in this setting has little efficacy in treating the congested state. Furthermore, effective pharmacotherapy has not been established. We report two patients with multiple myeloma and high-output heart failure who failed diuretic therapy. The patients were given dexamethasone in conjunction with lenalidomide and thalidomide, respectively. Shortly thereafter, each patient demonstrated a significant improvement in symptoms. This is the first report of successful treatment of multiple myeloma-induced high-output failure via the utilization of these agents.</p> <p>Case presentation</p> <p>Two patients with multiple myeloma were evaluated for volume overload. The first was a 50-year-old man with refractory disease. Magnetic resonance imaging demonstrated diffuse marrow replacement throughout the pelvis. Cardiac catheterization conveyed elevated filling pressures and a cardiac output of 15 liters/minute. He quickly decompensated and required mechanical ventilation. The second patient was a 61-year-old man recently diagnosed with multiple myeloma and volume overload. Skeletal survey demonstrated numerous lytic lesions throughout the pelvis. His cardiac catheterization also conveyed elevated filling pressures and a cardiac output of 10 liters/minute. Neither patient responded to diuretic therapy and they were subsequently started on dexamethasone plus lenalidomide and thalidomide, respectively. The first patient's brisk diuresis allowed for extubation within 48 hours after the first dose. He had a net negative fluid balance of 15 liters over 10 days. The second patient also quickly diuresed and on repeat cardiac catheterization, his cardiac output had normalized to 4.7 liters/minute.</p> <p>Conclusion</p> <p>Multiple myeloma can cause high-output failure. The mechanism is likely extensive bony involvement causing innumerable intramedullary arteriovenous fistulas. Diuretic therapy is not effective in treating this condition. Lenalidomide and thalidomide, both of which inhibit angiogenesis, seem to be viable treatment options. Based on the rapid and effective results seen in these two patients, a potential novel mechanism of 'pharmacologic fistula ligation' with these agents may be the most effective way to treat this presentation.</p

Onset of experimental severe cardiac fibrosis is mediated by overexpression of angiotensin-converting enzyme 2

Angiotensin-converting enzyme (ACE) 2 is a recently identified homologue of ACE. There is great interest in the therapeutic benefit for ACE2 overexpression in the heart. However, the role of ACE2 in the regulation of cardiac structure and function, as well as maintenance of systemic blood pressure, remains poorly understood. In cell culture, ACE2 overexpression led to markedly increased myocyte volume, assessed in primary rabbit myocytes. To assess ACE2 function in vivo, we used a recombinant adeno-associated virus 6 delivery system to provide 11-week overexpression of ACE2 in the myocardium of stroke-prone spontaneously hypertensive rats. ACE2, as well as the ACE inhibitor enalapril, significantly reduced systolic blood pressure. However, in the heart, ACE2 overexpression resulted in cardiac fibrosis, as assessed by histological analysis with concomitant deficits in ejection fraction and fractional shortening measured by echocardiography. Furthermore, global gene expression profiling demonstrated the activation of profibrotic pathways in the heart mediated by ACE2 gene delivery. This study demonstrates that sustained overexpression of ACE2 in the heart in vivo leads to the onset of severe fibrosis

Reduced-Order Modeling of Turbulent Reacting Flows with Application to Ramjets and Scramjets

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90621/1/AIAA-50272-117.pd

A Machine Checked Model of Idempotent MGU Axioms For Lists of Equational Constraints

We present formalized proofs verifying that the first-order unification algorithm defined over lists of satisfiable constraints generates a most general unifier (MGU), which also happens to be idempotent. All of our proofs have been formalized in the Coq theorem prover. Our proofs show that finite maps produced by the unification algorithm provide a model of the axioms characterizing idempotent MGUs of lists of constraints. The axioms that serve as the basis for our verification are derived from a standard set by extending them to lists of constraints. For us, constraints are equalities between terms in the language of simple types. Substitutions are formally modeled as finite maps using the Coq library Coq.FSets.FMapInterface. Coq's method of functional induction is the main proof technique used in proving many of the axioms.Comment: In Proceedings UNIF 2010, arXiv:1012.455

Effect of three diets on the gametogenic development and fatty acid profile of Paracentrotus lividus (Lamark, 1816) gonads

Original articleIn this study, the effects of three diets were investigated to enhance Paracentrotus lividus production for commercial purposes. P. lividus were fed ad libitum for 80 days with: diet A—fresh Codium tomentosum Stackhouse, 1797; diet B—formulated using a jellified mix of macroalgae and vegetables, including C. tomentosum (20%), Coralina sp. Linnaeus, 1758 (17%), cabbage Brassica oleracea var. capitata Linnaeus, 1753 (30%), carrot Daucus carota Linnaeus, 1753 (30%) and agar (3%) as a gelling agent. Diet C consisted of maize Zea mays Linnaeus, 1753 (56%) and New Zealand spinach Tetragonia tetragonoides (Pallas, 1781) Kuntze, 1891 (44%). Their effects on the gonadal and somatic growths, gonadosomatic index (GI) and gametogenesis were evaluated, as well as on the total lipid content and fatty acid composition of sea urchin's gonads. Diet A provided high values of eicosapentaenoic acid (EPA). Gonads of sea urchins fed with diet A were found mostly in growth and maturation stages of gametogenesis and showed the lowest lipid content. Sea urchins fed with diet B presented their gonads in the reabsorption stage and had the highest values of omega‐3 polyunsaturated fatty acids (PUFAs). Sea urchins fed with diet C were in the early stages of gametogenesis and had the highest values of lipid content, plus omega‐6 PUFAs. Once as an ingredient in a balanced mix with vegetables, C. tomentosum can be a key factor to the development of new promising high‐quality and low‐cost feed for P. lividus roe enhancementinfo:eu-repo/semantics/publishedVersio