Lift & Project Systems Performing on the Partial-Vertex-Cover Polytope

We study integrality gap (IG) lower bounds on strong LP and SDP relaxations derived by the Sherali-Adams (SA), Lovasz-Schrijver-SDP (LS+), and Sherali-Adams-SDP (SA+) lift-and-project (L&P) systems for the t-Partial-Vertex-Cover (t-PVC) problem, a variation of the classic Vertex-Cover problem in which only t edges need to be covered. t-PVC admits a 2-approximation using various algorithmic techniques, all relying on a natural LP relaxation. Starting from this LP relaxation, our main results assert that for every epsilon > 0, level-Theta(n) LPs or SDPs derived by all known L&P systems that have been used for positive algorithmic results (but the Lasserre hierarchy) have IGs at least (1-epsilon)n/t, where n is the number of vertices of the input graph. Our lower bounds are nearly tight. Our results show that restricted yet powerful models of computation derived by many L&P systems fail to witness c-approximate solutions to t-PVC for any constant c, and for t = O(n). This is one of the very few known examples of an intractable combinatorial optimization problem for which LP-based algorithms induce a constant approximation ratio, still lift-and-project LP and SDP tightenings of the same LP have unbounded IGs. We also show that the SDP that has given the best algorithm known for t-PVC has integrality gap n/t on instances that can be solved by the level-1 LP relaxation derived by the LS system. This constitutes another rare phenomenon where (even in specific instances) a static LP outperforms an SDP that has been used for the best approximation guarantee for the problem at hand. Finally, one of our main contributions is that we make explicit of a new and simple methodology of constructing solutions to LP relaxations that almost trivially satisfy constraints derived by all SDP L&P systems known to be useful for algorithmic positive results (except the La system).Comment: 26 page

Blood and hair as non-invasive trace element biological indicators in growing rabbits

[EN] The suitability of blood and hair as non-invasive tools to monitor trace element contents was studied in 48 Hyla male growing rabbits. Three diets with increasing organic selenium (Se) addition (0.1, 0.5 and 2.5 mg/kg) were used to induce alterations in the concentrations of trace elements vs. an unsupplemented diet. In blood, a linear decrease in Co (P<0.001), Cu (P<0.001), Mn (P<0.05), Zn (P<0.05), Sb (P<0.001), As (P<0.001), Cr (P<0.001), Mo (P<0.001), Ni (P<0.001) and Cd (P<0.001) concentrations with increasing dietary Se was observed. In hair, a cubic effect of dietary Se on Co (P<0.01), Cu (P<0.05), Mn (P<0.001), Pb (P<0.05), Mo (P<0.05) and Cd (P<0.05) concentrations was found, while As, Cr and Ni concentrations decreased linearly (P<0.01, P<0.01 and P<0.001, respectively) with increasing dietary Se. Selenium was negatively correlated to Sb, As, Cr, Mo, Ni and Cd, (P<0.001) in blood, and to As (P<0.05), Cr, Ni (P<0.01) and Pb (P<0.05) in hair. The contents of Se, As, Cr and Ni in blood were highly correlated (P<0.001) to those in hair. Blood appeared to be more sensitive than hair in detecting small changes in the trace element profile in rabbits, as was indicated by the discriminant analysis. In conclusion, blood and hair can be suitable biological indicators of essential, toxic and potentially toxic trace element status in rabbits, particularly when used complementarily.The authors are grateful to NUEVO S.A. (N Artaki, Euboia, Greece) for providing Sel-Plex®. This research has not received any specific funding.Papadomichelakis, G.; Pappas, AC.; Zoidis, E.; Danezis, G.; Georgiou, KA.; Fegeros, K. (2019). Blood and hair as non-invasive trace element biological indicators in growing rabbits. World Rabbit Science. 27(1):21-30. https://doi.org/10.4995/wrs.2019.10654SWORD2130271Barbosa F.J., Tanus-Santos J.E., Gerlach R.F., Parsons P.J. 2005. 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Elsevier: Amsterdam. https://doi.org/10.1016/B978-0-444-63340-8.00003-0Glynn A.W., Ilback N.G., Brabencova D., Carlsson L., Enqvist E.C., Netzel E., Oskarsson A. 1993. Influence of sodium selenite on 203Hg absorption, distribution and elimination in male mice exposed to methyl 203Hg. Biol. Trace Elem. Res., 39: 91-107. https://doi.org/10.1007/BF02783813Gulson B.L., Mizon K.J., Korsch M.J., Howarth D., Phillips A., Hall J. 1996. Impact on blood lead in children and adults following relocation from their source of exposure and contribution of skeletal tissue to blood lead. B. Environ. Contam. Tox., 56: 543-550. https://doi.org/10.1007/s001289900078Hasan M.Y., Kosanovic M., Fahim M.A., Adem A., Petroianu G. 2004. Trace metal profiles in hair samples from children in urban and rural region of the United Arab Emirates. Vet. Hum. Toxicol., 46: 119-121.He K. 2011. Trace elements in nails as biomarkers in clinical research. Eur. J. Clin. 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Health Persp., 19: 159-164. https://doi.org/10.1289/ehp.7719159López-Alonso M.L., Benedito J.L., Miranda M., Castillo C., Hernández J., Shore R.F. 2002. Cattle as biomonitors of soil arsenic, copper and zinc concentrations in Galicia (NW Spain). Arch. Environ. Contam. Toxicol., 43: 103-108. https://doi.org/10.1007/s00244-002-1168-5McDowell L.R. 2003. 'Minerals in animal and human nutrition (2nd ed)'. (Elsevier Science: Amsterdam).Milošković A., Simić V. 2015. Arsenic and other trace elements in five edible fish species in relation to fish size and weight and potential health risks for human consumption. Pol. J. Environ. Stud., 24: 199-206. https://doi.org/10.15244/pjoes/24929Miranda M., López-Alonso M., Castillo C., Hernández J., Benedito J.L. 2005. Effects of moderate pollution on toxic and trace metal levels in calves from a polluted area of northern Spain. Environ. Int., 31: 543-548.https://doi.org/10.1016/j.envint.2004.09.025Ohta H., Seki Y., Yoshikawa H. 1995. Interactive effects of selenium on chronic cadmium toxicity in rats. ACES Bulletin, 8: 97-104. Othman A.I., El Missiry M.A. 1998. Role of selenium against lead toxicity in male rats. J. Biochem. Mol. Toxic., 12: 345-349. https://doi.org/10.1002/(SICI)1099-0461(1998)12:6%3C345::AID-JBT4%3E3.0.CO;2-VPapadomichelakis G., Zoidis E., Pappas A.C., Mountzouris K.C., Fegeros K. 2017. Effects of increasing dietary organic selenium levels on meat fatty acid composition and oxidative stability in growing rabbits. Meat Sci., 131: 132-138. https://doi.org/10.1016/j.meatsci.2017.05.006Papadomichelakis G., Zoidis E., Pappas A.C., Danezis G., Georgiou C.A., Fegeros K. 2018. Dietary organic selenium addition and accumulation of toxic and essential trace elements in liver and meat of growing rabbits. Meat Sci., 145: 383-388. https://doi.org/10.1016/j.meatsci.2018.07.022Pappas A.C., Zoidis E., Georgiou C.A., Demiris N., Surai P.F., Fegeros K. 2011. Influence of organic selenium supplementation on the accumulation of toxic and essential trace elements involved in the antioxidant systemof chicken. Food Addit. Contam. Part A, 28: 446-454. https://doi.org/10.1080/19440049.2010.549152Park D.U., Kim D.S., Yu S.D., Lee K.M., Ryu S.H., Kim S.G. et al. 2014. Blood levels of cadmium and lead in residents near abandoned metal mine areas in Korea. Environ. Monit. Assess., 186: 5209-5220. https://doi.org/10.1007/s10661-014-3770-1Patra R.C., Swarup D., Naresh R., Kumar P., Nandi D., Shekhar P., Roy S., Ali S.L. 2007. Tail hair as an indicator of environmental exposure of cows to lead and cadmium in different industrial areas. Ecotoxicol. Environ. Saf., 66: 127-131. https://doi.org/10.1016/j.ecoenv.2006.01.005Paukert J., Obrusnik I. 1986. The hair of the common hare (Lepus europaeus Pall.) and of the common vole (Microtus arvalis Pall.) as indicator of the environmental pollution. J. Hyg. Epidem. Microb. 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Power-law scaling in intratumoral microbiota of colorectal cancer

It has recently been proposed that the study of microbial dynamics in humans may gain insights from island biogeographical theory. Here, we test whether the diversity of the intratumoral microbiota of colorectal cancer tumors (CRC) follows a power law with tumor size akin to the island species-area relationship. We confirm a direct correlation between the quantity of Amplicon Sequence Variants (ASVs) within CRC tumors and tumor sizes, following a (log)power model, explaining 47% of the variation. Understanding the processes involved, potentially through the analogy of tumors and islands, may ultimately contribute to future clinical and therapeutic strategies

Power-law scaling in intratumoral microbiota of colorectal cancer

It has recently been proposed that the study of microbial dynamics in humans may gain insights from island biogeographical theory. Here, we test whether the diversity of the intratumoral microbiota of colorectal cancer tumors (CRC) follows a power law with tumor size akin to the island species-area relationship. We confirm a direct correlation between the quantity of Amplicon Sequence Variants (ASVs) within CRC tumors and tumor sizes, following a (log)power model, explaining 47% of the variation. Understanding the processes involved, potentially through the analogy of tumors and islands, may ultimately contribute to future clinical and therapeutic strategies

Local Commutativity and Causality in Interacting PP-wave String Field Theory

In this paper, we extend our previous study of causality and local commutativity of string fields in the pp-wave lightcone string field theory to include interaction. Contrary to the flat space case result of Lowe, Polchinski, Susskind, Thorlacius and Uglum, we found that the pp-wave interaction does not affect the local commutativity condition. Our results show that the pp-wave lightcone string field theory is not continuously connected with the flat space one. We also discuss the relation between the condition of local commutativity and causality. While the two notions are closely related in a point particle theory, their relation is less clear in string theory. We suggest that string local commutativity may be relevant for an operational defintion of causality using strings as probes.Comment: Latex, JHEP3.cls, 18 pages, no figures. v2: add comments about the UV-IR mixing effect displayed in our result. version to appear in JHE

Twistor Strings with Flavour

We explore the tree-level description of a class of N=2 UV-finite SYM theories with fundamental flavour within a topological B-model twistor string framework. In particular, we identify the twistor dual of the Sp(N) gauge theory with one antisymmetric and four fundamental hypermultiplets, as well as that of the SU(N) theory with 2N hypermultiplets. This is achieved by suitably orientifolding/orbifolding the original N=4 setup of Witten and adding a certain number of new topological 'flavour'-branes at the orientifold/orbifold fixed planes to provide the fundamental matter. We further comment on the appearance of these objects in the B-model on CP(3|4). An interesting aspect of our construction is that, unlike the IIB description of these theories in terms of D3 and D7-branes, on the twistor side part of the global flavour symmetry is realised geometrically. We provide evidence for this correspondence by calculating and matching amplitudes on both sides.Comment: 38+12 pages; uses axodraw.sty. v2: References added, minor clarification

Beneficial effect of the oxygen free radical scavenger amifostine (WR-2721) on spinal cord ischemia/reperfusion injury in rabbits

<p>Abstract</p> <p>Background</p> <p>Paraplegia is the most devastating complication of thoracic or thoraco-abdominal aortic surgery. During these operations, an ischemia-reperfusion process is inevitable and the produced radical oxygen species cause severe oxidative stress for the spinal cord. In this study we examined the influence of Amifostine, a triphosphate free oxygen scavenger, on oxidative stress of spinal cord ischemia-reperfusion in rabbits.</p> <p>Methods</p> <p>Eighteen male, New Zealand white rabbits were anesthetized and spinal cord ischemia was induced by temporary occlusion of the descending thoracic aorta by a coronary artery balloon catheter, advanced through the femoral artery. The animals were randomly divided in 3 groups. Group I functioned as control. In group II the descending aorta was occluded for 30 minutes and then reperfused for 75 min. In group III, 500 mg Amifostine was infused into the distal aorta during the second half-time of ischemia period. At the end of reperfusion all animals were sacrificed and spinal cord specimens were examined for superoxide radicals by an ultra sensitive fluorescent assay.</p> <p>Results</p> <p>Superoxide radical levels ranged, in group I between 1.52 and 1.76 (1.64 ± 0.10), in group II between 1.96 and 2.50 (2.10 ± 0.23), and in group III (amifostine) between 1.21 and 1.60 (1.40 ± 0.19) (p = 0.00), showing a decrease of 43% in the Group of Amifostine. A lipid peroxidation marker measurement ranged, in group I between 0.278 and 0.305 (0.296 ± 0.013), in group II between 0.427 and 0.497 (0.463 ± 0.025), and in group III (amifostine) between 0.343 and 0.357 (0.350 ± 0.007) (p < 0.00), showing a decrease of 38% after Amifostine administration.</p> <p>Conclusion</p> <p>By direct and indirect methods of measuring the oxidative stress of spinal cord after ischemia/reperfusion, it is suggested that intra-aortic Amifostine infusion during spinal cord ischemia phase, significantly attenuated the spinal cord oxidative injury in rabbits.</p

Familial hypercholesterolaemia in children and adolescents from 48 countries: a cross-sectional study

Background: Approximately 450 000 children are born with familial hypercholesterolaemia worldwide every year, yet only 2·1% of adults with familial hypercholesterolaemia were diagnosed before age 18 years via current diagnostic approaches, which are derived from observations in adults. We aimed to characterise children and adolescents with heterozygous familial hypercholesterolaemia (HeFH) and understand current approaches to the identification and management of familial hypercholesterolaemia to inform future public health strategies. Methods: For this cross-sectional study, we assessed children and adolescents younger than 18 years with a clinical or genetic diagnosis of HeFH at the time of entry into the Familial Hypercholesterolaemia Studies Collaboration (FHSC) registry between Oct 1, 2015, and Jan 31, 2021. Data in the registry were collected from 55 regional or national registries in 48 countries. Diagnoses relying on self-reported history of familial hypercholesterolaemia and suspected secondary hypercholesterolaemia were excluded from the registry; people with untreated LDL cholesterol (LDL-C) of at least 13·0 mmol/L were excluded from this study. Data were assessed overall and by WHO region, World Bank country income status, age, diagnostic criteria, and index-case status. The main outcome of this study was to assess current identification and management of children and adolescents with familial hypercholesterolaemia. Findings: Of 63 093 individuals in the FHSC registry, 11 848 (18·8%) were children or adolescents younger than 18 years with HeFH and were included in this study; 5756 (50·2%) of 11 476 included individuals were female and 5720 (49·8%) were male. Sex data were missing for 372 (3·1%) of 11 848 individuals. Median age at registry entry was 9·6 years (IQR 5·8-13·2). 10 099 (89·9%) of 11 235 included individuals had a final genetically confirmed diagnosis of familial hypercholesterolaemia and 1136 (10·1%) had a clinical diagnosis. Genetically confirmed diagnosis data or clinical diagnosis data were missing for 613 (5·2%) of 11 848 individuals. Genetic diagnosis was more common in children and adolescents from high-income countries (9427 [92·4%] of 10 202) than in children and adolescents from non-high-income countries (199 [48·0%] of 415). 3414 (31·6%) of 10 804 children or adolescents were index cases. Familial-hypercholesterolaemia-related physical signs, cardiovascular risk factors, and cardiovascular disease were uncommon, but were more common in non-high-income countries. 7557 (72·4%) of 10 428 included children or adolescents were not taking lipid-lowering medication (LLM) and had a median LDL-C of 5·00 mmol/L (IQR 4·05-6·08). Compared with genetic diagnosis, the use of unadapted clinical criteria intended for use in adults and reliant on more extreme phenotypes could result in 50-75% of children and adolescents with familial hypercholesterolaemia not being identified. Interpretation: Clinical characteristics observed in adults with familial hypercholesterolaemia are uncommon in children and adolescents with familial hypercholesterolaemia, hence detection in this age group relies on measurement of LDL-C and genetic confirmation. Where genetic testing is unavailable, increased availability and use of LDL-C measurements in the first few years of life could help reduce the current gap between prevalence and detection, enabling increased use of combination LLM to reach recommended LDL-C targets early in life

Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good

Severe early onset preeclampsia: short and long term clinical, psychosocial and biochemical aspects

Preeclampsia is a pregnancy specific disorder commonly defined as de novo hypertension and proteinuria after 20 weeks gestational age. It occurs in approximately 3-5% of pregnancies and it is still a major cause of both foetal and maternal morbidity and mortality worldwide1. As extensive research has not yet elucidated the aetiology of preeclampsia, there are no rational preventive or therapeutic interventions available. The only rational treatment is delivery, which benefits the mother but is not in the interest of the foetus, if remote from term. Early onset preeclampsia (<32 weeks’ gestational age) occurs in less than 1% of pregnancies. It is, however often associated with maternal morbidity as the risk of progression to severe maternal disease is inversely related with gestational age at onset2. Resulting prematurity is therefore the main cause of neonatal mortality and morbidity in patients with severe preeclampsia3. Although the discussion is ongoing, perinatal survival is suggested to be increased in patients with preterm preeclampsia by expectant, non-interventional management. This temporising treatment option to lengthen pregnancy includes the use of antihypertensive medication to control hypertension, magnesium sulphate to prevent eclampsia and corticosteroids to enhance foetal lung maturity4. With optimal maternal haemodynamic status and reassuring foetal condition this results on average in an extension of 2 weeks. Prolongation of these pregnancies is a great challenge for clinicians to balance between potential maternal risks on one the eve hand and possible foetal benefits on the other. Clinical controversies regarding prolongation of preterm preeclamptic pregnancies still exist – also taking into account that preeclampsia is the leading cause of maternal mortality in the Netherlands5 - a debate which is even more pronounced in very preterm pregnancies with questionable foetal viability6-9. Do maternal risks of prolongation of these very early pregnancies outweigh the chances of neonatal survival? Counselling of women with very early onset preeclampsia not only comprises of knowledge of the outcome of those particular pregnancies, but also knowledge of outcomes of future pregnancies of these women is of major clinical importance. This thesis opens with a review of the literature on identifiable risk factors of preeclampsia