A study of the Z production cross-section in pp collisions at √s = 7 using tau final states

A measurement of the inclusive Z → ττ cross-section in pp collisions at √s =7 is presented based on a dataset of 1.0 fb[superscript −1] collected by the LHCb detector. Candidates for Z → τ τ decays are identified through reconstructed final states with two muons, a muon and an electron, a muon and a hadron, or an electron and a hadron. The production cross-section for Z bosons, with invariant mass between 60 and 120 GeV/c[superscript 2], which decay to τ leptons with transverse momenta greater than 20 GeV/c and pseudorapidities between 2.0 and 4.5, is measured to be σ[subscript pp]→Z→ττ = 71.4 ± 3.5 ± 2.8 ± 2.5 pb; the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the integrated luminosity. The ratio of the cross-sections for Z → τ τ to Z → μμ is determined to be 0.93 ± 0.09, where the uncertainty is the combination of statistical, systematic, and luminosity uncertainties of the two measurements.National Science Foundation (U.S.

Precision measurement of the B0s-B¯0s oscillation frequency with the decay B0s → D−sπ+

A key ingredient to searches for physics beyond the Standard Model in B0s mixing phenomena is the measurement of the B0s– ${{\overline{ {\mathrm {B}}}{}}^0_{\mathrm { s}}}$ oscillation frequency, which is equivalent to the mass difference Δms of the B0s mass eigenstates. Using the world's largest B0s meson sample accumulated in a dataset, corresponding to an integrated luminosity of 1.0 fb−1, collected by the LHCb experiment at the CERN LHC in 2011, a measurement of Δms is presented. A total of about 34 000 B0s → D−sπ+ signal decays are reconstructed, with an average decay time resolution of 44 fs. The oscillation frequency is measured to be Δms = 17.768 ± 0.023 (stat) ± 0.006 (syst) ps−1, which is the most precise measurement to date

Laparoscopy in management of appendicitis in high-, middle-, and low-income countries: a multicenter, prospective, cohort study.

BACKGROUND: Appendicitis is the most common abdominal surgical emergency worldwide. Differences between high- and low-income settings in the availability of laparoscopic appendectomy, alternative management choices, and outcomes are poorly described. The aim was to identify variation in surgical management and outcomes of appendicitis within low-, middle-, and high-Human Development Index (HDI) countries worldwide. METHODS: This is a multicenter, international prospective cohort study. Consecutive sampling of patients undergoing emergency appendectomy over 6 months was conducted. Follow-up lasted 30 days. RESULTS: 4546 patients from 52 countries underwent appendectomy (2499 high-, 1540 middle-, and 507 low-HDI groups). Surgical site infection (SSI) rates were higher in low-HDI (OR 2.57, 95% CI 1.33-4.99, p = 0.005) but not middle-HDI countries (OR 1.38, 95% CI 0.76-2.52, p = 0.291), compared with high-HDI countries after adjustment. A laparoscopic approach was common in high-HDI countries (1693/2499, 67.7%), but infrequent in low-HDI (41/507, 8.1%) and middle-HDI (132/1540, 8.6%) groups. After accounting for case-mix, laparoscopy was still associated with fewer overall complications (OR 0.55, 95% CI 0.42-0.71, p < 0.001) and SSIs (OR 0.22, 95% CI 0.14-0.33, p < 0.001). In propensity-score matched groups within low-/middle-HDI countries, laparoscopy was still associated with fewer overall complications (OR 0.23 95% CI 0.11-0.44) and SSI (OR 0.21 95% CI 0.09-0.45). CONCLUSION: A laparoscopic approach is associated with better outcomes and availability appears to differ by country HDI. Despite the profound clinical, operational, and financial barriers to its widespread introduction, laparoscopy could significantly improve outcomes for patients in low-resource environments. TRIAL REGISTRATION: NCT02179112

Metformin-induced lactic acidosis: a case series

<p>Abstract</p> <p>Introduction</p> <p>Unlike other agents used in the treatment of type 2 diabetes mellitus, metformin has been shown to reduce mortality in obese patients. It is therefore being increasingly used in higher doses. The major concern of many physicians is a possible risk of lactic acidosis. The reported frequency of metformin related lactic acidosis is 0.05 per 1000 patient-years; some authors advocate that this rate is equal in those patients not taking metformin.</p> <p>Case presentation</p> <p>We present two case reports of metformin-associated lactic acidosis. The first case is a 77 year old female with a past medical history of hypertension and type 2 diabetes mellitus who had recently been prescribed metformin (3 g/day), perindopril and acetylsalicylic acid. She was admitted to the emergency department two weeks later with abdominal pain and psychomotor agitation. Physical examination revealed only signs of poor perfusion. Laboratory evaluation revealed hyperkalemia, elevated creatinine and blood urea nitrogen and mild leukocytosis. Arterial blood gases showed severe lactic acidemia. She was admitted to the intensive care unit. Vasopressor and ventilatory support was initiated and continuous venovenous hemodiafiltration was instituted. Twenty-four hours later, full clinical recovery was observed, with return to a normal serum lactate level. The patient was discharged from the intensive care unit on the sixth day. The second patient is a 69 year old male with a past medical history of hypertension, type 2 diabetes mellitus and ischemic heart disease who was on metformin (4 g/day), glycazide, acetylsalicylic acid and isosorbide dinitrate. He was admitted to the emergency department in shock with extreme bradycardia. Initial evaluation revealed severe lactic acidosis and elevated creatinine and urea. The patient was admitted to the Intensive Care Unit and commenced on continuous venovenous hemodiafiltration in addition to other supportive measures. A progressive recovery was observed and he was discharged from the intensive care unit on the seventh day.</p> <p>Conclusion</p> <p>We present two case reports of severe lactic acidosis most probably associated with high doses of metformin in patients with no known contraindications for metformin prescription. In both patients no other condition was identified to cause such severe lactic acidosis. Although controversial, lactic acidosis should be considered in patients taking metformin.</p

Species diversity and flagellate infections in the sand fly fauna near Porto Grande, State of Amapá, Brazil (Diptera: Psychodidae. Kinetoplastida: Trypanosomatidae)

Forty-six species of Lutzomyia and one species of Brumptomyia were identified among 20,008 sand flies collected in central Amapá. L. squamiventris maripaensis, L. infraspinosa, L. umbratilis and L. ubiquitalis accounted for 66% of the specimens caught in light traps, and L. umbratilis was the commonest of the 16 species found on tree bases. Seven species of Lutzomyia including L. umbratilis were collected in a plantation of Caribbean pine. Sixty out of 511 female sand flies dissected were positive for flagellates. Among the sand flies from which Leishmania was isolated, promastigotes were observed in the salivary glands and foregut of 13 out of 21 females scored as having very heavy infections in the remainder of the gut, reinforcing the idea that salivary gland invasion may be part of the normal life cycle of Leishmania in nature. Salivary gland infections were detected in specimens of L. umbratilis, L. whitmani and L. spathotrichia. Parasites isolated from L. umbratilis, L. whitmani and also from one specimen of L. dendrophyla containing the remains of a bloodmeal, were compatible with Le. guyanensis by morphology and behaviour in hamsters

Updated measurement of time-dependent CP -violating observables in Bs0→J/ψ^K+^K- decays

The decay-time-dependent $CP$ asymmetry in $B^{0}_{s}\to J/\psi K^{+} K^{-}$ decays is measured using proton-proton collision data, corresponding to an integrated luminosity of $1.9\,\mathrm{fb^{-1}}$, collected with the LHCb detector at a centre-of-mass energy of $13\,\mathrm{TeV}$ in 2015 and 2016. Using a sample of approximately 117\,000 signal decays with an invariant $K^{+} K^{-}$ mass in the vicinity of the $\phi(1020)$ resonance, the $CP$-violating phase $\phi_s$ is measured, along with the difference in decay widths of the light and heavy mass eigenstates of the $B^{0}_{s}$-$\bar{B}^{0}_{s}$ system, $\Delta\Gamma_s$. The difference of the average $B^{0}_{s}$ and $B^{0}$ meson decay widths, $\Gamma_s-\Gamma_d$, is determined using in addition a sample of $B^{0} \to J/\psi K^{+} \pi^{-}$ decays. The values obtained are $\phi_s = -0.083\pm0.041\pm0.006\,\mathrm{rad}$, $\Delta\Gamma_s = 0.077 \pm 0.008 \pm 0.003\, \mathrm{ps^{-1}}$ and $\Gamma_s-\Gamma_d = -0.0041 \pm 0.0024 \pm 0.0015\,\mathrm{ps^{-1}}$, where the first uncertainty is statistical and the second systematic. These are the most precise single measurements of these quantities to date and are consistent with expectations based on the Standard Model and with a previous LHCb analysis of this decay using data recorded at centre-of-mass energies 7 and 8 TeV. Finally, the results are combined with recent results from $B^{0}_{s}\to J/\psi \pi^{+} \pi^{-}$ decays obtained using the same dataset as this analysis, and with previous independent LHCb results

The rank reversal problem in multi-criteria decision making : a literature review

Despite the importance of multicriteria decision-making (MCDM) techniques for constructing effective decision models, there are many criticisms due to the occurrence of a problem called rank reversal. Nevertheless, there is a lack of a systematic literature review on this important subject which involves different methods. This study reviews the pertinent literature on rank reversal, based on 130 related articles published from 1980 to 2015 in international journals, which were gathered and analyzed according to the following perspectives: multicriteria technique, year and journal in which the papers were published, co-authorship network, rank reversal types, and research goal. Thus our survey provides recommendations for future research, besides useful information and knowledge regarding rank reversal in the MCDM field

Differential branching fraction and angular analysis of the decay B s0 → φμ + μ -

The determination of the differential branching fraction and the first angular analysis of the decay Bs0 → φμ + μ - are presented using data, corresponding to an integrated luminosity of 1.0 fb-1, collected by the LHCb experiment at √s=7 TeV. The differential branching fraction is determined in bins of q 2, the invariant dimuon mass squared. Integration over the full q 2 range yields a total branching fraction of B (Bs0 → φμ + μ -(7.07 -0.59+0.64± 0.71± 0.71) × 10 -7, where the first uncertainty is statistical, the second systematic, and the third originates from the branching fraction of the normalisation channel. An angular analysis is performed to determine the angular observables F L, S 3, A 6, and A 9. The observables are consistent with Standard Model expectations. [Figure not available: see fulltext.] © 2013 CERN for the benefit of the LHCb collaboration