Directional discrepancy in two dimensions

In the present paper, we study the geometric discrepancy with respect to families of rotated rectangles. The well-known extremal cases are the axis-parallel rectangles (logarithmic discrepancy) and rectangles rotated in all possible directions (polynomial discrepancy). We study several intermediate situations: lacunary sequences of directions, lacunary sets of finite order, and sets with small Minkowski dimension. In each of these cases, extensions of a lemma due to Davenport allow us to construct appropriate rotations of the integer lattice which yield small discrepancy

Contractual Versus Non-Contractual Trade: The Role of Institutions in China

Recent research has demonstrated the importance of institutional quality at the country level for both the volume of trade and the ability to trade in differentiated goods that rely on contract enforcement. This paper takes advantage of cross-provincial variation in institutional quality in China, and export data that distinguishes between foreign and domestic exporters and processing versus ordinary trade, to show that institutional quality is a significant factor in determining Chinese provincial export patterns. Institutions matter more for processing trade, and more for foreign firms, just as we would expect from a greater reliance on contracts in these cases.

Genome scan of Diabrotica virgifera virgifera for genetic variation associated with crop rotation tolerance

Crop rotation has been a valuable technique for control of Diabrotica virgifera virgifera for almost a century. However, during the last two decades, crop rotation has ceased to be effective in an expanding area of the US corn belt. This failure appears to be due to a change in the insect's oviposition behaviour, which, in all probability, has an underlying genetic basis. A preliminary genome scan using 253 amplified fragment-length polymorphism (AFLP) markers sought to identify genetic variation associated with the circumvention of crop rotation. Samples of D. v. virgifera from east-central Illinois, where crop rotation is ineffective, were compared with samples from Iowa at locations that the behavioural variant has yet to reach. A single AFLP marker showed signs of having been influenced by selection for the circumvention of crop rotation. However, this marker was not diagnostic. The lack of markers strongly associated with the trait may be due to an insufficient density of marker coverage throughout the genome. A weak but significant general heterogeneity was observed between the Illinois and Iowa samples at microsatellite loci and AFLP markers. This has not been detected in previous population genetic studies of D. v. virgifera and may indicate a reduction in gene flow between variant and wild-type beetles

Late stage C―H activation of a privileged scaffold; synthesis of a library of benzodiazepines

A library of over twenty 5-(2-arylphenyl)-1,3-dihydro-2H-1,4-benzodiazepin-2-ones has been formed by a microwave-mediated late-stage palladium-catalysed arylation of 1,4-benzodiazepines using diaryliodonium salts. This can also be applied to nordazepam (7-chloro-5-phenyl-1,3-dihydro-2H-1,4-benzodiazepin-2-one), the active metabolite of diazepam, and subsequent N-alkylation and/or H/D exchange allows further diversification towards elaborated pharmaceuticals and their 3,3'-deuterated analogues

Directional discrepancy in two dimensions

In the present paper, we study the geometric discrepancy with respect to families of rotated rectangles. The well-known extremal cases are the axis-parallel rectangles (logarithmic discrepancy) and rectangles rotated in all possible directions (polynomial discrepancy). We study several intermediate situations: lacunary sequences of directions, lacunary sets of finite order, and sets with small Minkowski dimension. In each of these cases, extensions of a lemma due to Davenport allow us to construct appropriate rotations of the integer lattice which yield small discrepancy

Point of care creatinine testing in diagnostic imaging: A feasibility study within the outpatient computed tomography setting

Introduction: Although the risks associated with iodinated contrast administration are acknowledged to be very low, screening of kidney function prior to administration is still standard practice in many hospitals. This study has evaluated the feasibility of implementing a screening form in conjunction with point of care (PoC) creatinine testing as a method to manage the risks of post contrast acute kidney injury (PC-AKI) within the CT imaging pathway. Method: Over an eight-week period 300 adult outpatients attending a UK CT department for contrast-enhanced scans were approached. Participants completed a screening questionnaire for co-morbidities linked to kidney dysfunction and consented to have a PoC and laboratory creatinine tests. Comparison was made against with previous baseline blood tests obtained within the preceding 3 months, as required by the study site. Participants were also invited to attend for follow up PoC and laboratory bloods tests at 48–72 h. Results: 14 patients (4.7%) had a scan-day eGFR below 45mL/min/1.73m2, all identified through screening. The majority of patients (n=281/300; 93.7%) fell in the same risk category based on previous and scan-day blood results. Six PoC test failures were recorded on the scan day. The constant error between the Abbott i-STAT PoC scan-day measurements and the laboratory scan-day measurements was -3.71 (95% CI: -6.41 to -0.50). Five patients had an elevated creatinine (≥25% from baseline) post contrast administration, but no instances of PC-AKI (≥50% from baseline) were identified. Conclusion: PoC creatinine testing is a practical method of ensuring renal function and is feasible in the radiology environment

Risk of postoperative hypoxemia in ambulatory orthopedic surgery patients with diagnosis of obstructive sleep apnea: a retrospective observational study

<p>Abstract</p> <p>Background</p> <p>It is unclear when it is safe to discharge patients with a diagnosis of Obstructive Sleep Apnea (OSA) after ambulatory surgical procedures due to concern for postoperative respiratory compromise and hypoxemia. Our OSA patients undergoing ambulatory-type orthopedic procedures are monitored overnight in the PACU, thus we reviewed patient records to determine incidence of complications.</p> <p>Methods</p> <p>Two hundred and six charts of patients with preoperative diagnosis of OSA based on ICD-9 codes were reviewed for outcomes including episodes of hypoxemia. Univariate analysis followed by logistic regression and propensity analysis was performed to determine independent risk factors for hypoxemia and association with adverse outcomes.</p> <p>Results</p> <p>The majority of patients had regional anesthesia (95%). Thirty four percent of patients had hypoxemia in the PACU. Initial risk factors for hypoxemia identified by univariate analysis were BMI ≥ 35, increased age, history of COPD, upper extremity procedure, and use of peripheral nerve block. Independent risk factors identified by logistic regression were history of COPD (OR 3.64 with 95% CI 1.03-12.88) and upper extremity procedure (2.53, 1.36-4.68). After adjustment with propensity scores, adverse events were rare, and unplanned hospital admission after PACU stay was not increased with hypoxemia (11% vs 16%)</p> <p>Conclusions</p> <p>Episodes of postoperative hypoxemia in OSA patients undergoing ambulatory surgery with regional anesthesia are not associated with increased adverse outcomes or unplanned hospital admission.</p