Practical quantum key distribution over a 48-km optical fiber network

The secure distribution of the secret random bit sequences known as "key" material, is an essential precursor to their use for the encryption and decryption of confidential communications. Quantum cryptography is a new technique for secure key distribution with single-photon transmissions: Heisenberg's uncertainty principle ensures that an adversary can neither successfully tap the key transmissions, nor evade detection (eavesdropping raises the key error rate above a threshold value). We have developed experimental quantum cryptography systems based on the transmission of non-orthogonal photon states to generate shared key material over multi-kilometer optical fiber paths and over line-of-sight links. In both cases, key material is built up using the transmission of a single-photon per bit of an initial secret random sequence. A quantum-mechanically random subset of this sequence is identified, becoming the key material after a data reconciliation stage with the sender. Here we report the most recent results of our optical fiber experiment in which we have performed quantum key distribution over a 48-km optical fiber network at Los Alamos using photon interference states with the B92 and BB84 quantum key distribution protocols.Comment: 13 pages, 7 figures, .pdf format submitted to Journal of Modern Optic

Effects of biceps tension and superior humeral head translation on the glenoid labrum

We sought to understand the effects of superior humeral head translation and load of the long head of biceps on the pathomechanics of the superior glenoid labrum by predicting labral strain. Using micro‐CT cadaver images, a finite element model of the glenohumeral joint was generated, consisting of humerus, glenoid bone, cartilages, labrum, and biceps tendon. A glenohumeral compression of 50 N and biceps tensions of 0, 22, 55, and 88 N were applied. The humeral head was superiorly translated from 0 to 5 mm in 1‐mm increments. The highest labral strain occurred at the interface with the glenoid cartilage and bone beneath the origin of the biceps tendon. The maximum strain was lower than the reported failure strain. The humeral head motion had relatively greater effect than biceps tension on the increasing labral strain. This supports the mechanistic hypothesis that superior labral lesions result mainly from superior migration of the humeral head, but also from biceps tension. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1424–1429, 2014.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108670/1/jor22688.pd

Effects of biceps tension on the torn superior glenoid labrum

The purpose of this study was to evaluate the role of the tension on the long head of the biceps tendon in the propagation of SLAP tears by studying the mechanical behavior of the torn superior glenoid labrum. A previously validated finite element model was extended to include a glenoid labrum with type II SLAP tears of three different sizes. The strain distribution within the torn labral tissue with loading applied to the biceps tendon was investigated and compared to the inact and unloaded conditions. The anterior and posterior edges of each SLAP tear experienced the highest strain in the labrum. Labral strain increased with increasing biceps tension. This effect was stronger in the labrum when the size of the tear exceeded the width of the biceps anchor on the superior labrum. Thus, this study indicates that biceps tension influences the propagation of a SLAP tear more than it does the initiation of a tear. Additionally, it also suggests that the tear size greater than the biceps anchor site as a criterion in determining optimal treatment of a type II SLAP tear. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1545–1551, 2015.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113101/1/jor22888.pd

Collaborative Research: Did the Laurentine Ice Sheet Control Abrupt Climate Change?

This is a collaborative project with the University of Maine and Ohio State University. The Principal Investigators will model the late glacial Laurentide Ice Sheet from near steady-state equilibrium at - 25,000 BP (years before present), through reversible stadial/interstadial transitions associated with Laurentide iceberg outbursts (Heinrich events 2 and 1), and across the threshold of irreversible Laurentide collapse after the last iceberg outburst at - 1 1,000 BP (Heinrich event 0). The goals are to determine if ice-sheet changes could have triggered climate changes by abrupt ice sheet change and to investigate the structure of these changes. The Principal Investigators will isolate mechanisms of abrupt change over hundreds of years in the ice sheet that are large enough to trigger climate changes captured as time snapshots by coupled global and regional atmospheric climate models. Specific modeling tasks are: 1) to provide the climate settings surrounding the Laurentide Ice Sheet at snapshots of time during this late glacial period. This includes the wind field over the ice sheet, proglacial lakes along the border, the fine-resolution mesoscale climate of North America, and global climate; 2) to provide the basal boundary conditions that, together with the internal flow and temperature fields, are used to calculate the basal mass balance. This includes the pattern of basal temperatures, melting and freezing rates, and the associated subglacial hydrology; 3) to model the Laurentide Ice Sheet basal thermal, hydrological, and mechanical conditions within the imposed and basal boundary constraints for the chosen timeframe; and 4) to determine whether modeling will isolate mechanisms of abrupt change that allow rapid advance and retreat of Laurentide ice, with areal, elevation, and volume changes large enough to trigger climate changes that are captured by our snapshots of regional and global climate.This project has significance for educational outreach and the possible behavior of present-day ice sheets. The education outreach program will be interactive with high school students. They will be able to manipulate the major variables so that they can view three-dimensional computer simulations of how the Laurentide Ice Sheet responds to each variable. This program will be disseminated on the world-wide web. If fluctuations in the Laurentide Ice Sheet triggered climate changes, then the possibility exists that present-day ice sheets covering Greenland and Antarctica could trigger similar climate changes, with major social, economic, and political consequences. A way to assess this possibility is to understand the internal instability mechanisms that could have caused abrupt changes in Laurentide ice extent, and to tie them firmly to known late glacial climate changes

Unusual Nucleophilic Addition of Grignard Reagents in the Synthesis of 4-Amino-pyrimidines

Pyrimidines have always received considerable attention because of their importance in synthesis and elucidation of biochemical roles, in particular that of vitamin B1. Herein, we describe a reaction pathway in a Grignard reagent-based synthesis of substituted pyrimidines. A general synthesis of α-keto-2-methyl-4-amino pyrimidines and their C6-substituted analogues from 4-amino-5-cyano-2-methylpyrimidine is reported. The presence of the nitrile substituent in the starting material also results in an unusual reaction pathway leading to C6-substituted 1,2-dihydropyrimidines. Grignard reagents that give normal pyrimidine products under standard reaction conditions can be 14 switched to give dihydropyrimidines by holding the reaction at 0 °C before quenching

Intertidal invertebrate harvesting: a meta-analysis of impacts and recovery in an important waterbird prey resource

Harvesting of marine invertebrates in intertidal areas often comes into conflict with conservation objectives for waterbird populations of the orders Anseriformes and Charadriiformes. We present a meta-analysis of the relationships between benthic invertebrate communities and various sources of intertidal harvesting disturbance to investigate impacts and recovery in bird prey resources. The effect size (Hedges’ d) of harvesting on benthic species abundance, diversity and biomass was calculated for 38 studies in various locations globally, derived from 16 publications captured through a systematic review process that met the meta-analysis inclusion criteria. A negative response to harvesting disturbance was found for all taxa, including both target and non-target species, that represent important types of waterbird prey. Impacts appear most severe from hand-gathering, which significantly reduces the abundance of target polychaete species, a key prey group for many bird species. Across all gear types, non-target species demonstrate a larger reduction in abundance compared to target species. Recovery trends vary, with differences observed between taxonomic groups and gear/habitat combinations. Abundance of bivalve molluscs, a potentially highly profitable bird prey item, is suppressed for >60 d by mechanical dredging in intertidal mud, while annelid and crustacean abundances demonstrate near recovery over the same period. Data suggest that recovery following harvesting in sandier habitats may in some cases take as long as or longer than in muddy sediments. We recommend management measures to minimise disturbance to benthic prey resources and support conservation objectives for waterbird populations to meet international legal requirements

Pan-aortic hybrid treatment of mega-aorta syndrome

Hybrid procedures combining traditional open and newer endovascular techniques are increasingly used to treat complex aortic disease. We present a novel approach for total aortic replacement, including hybrid repair of the arch and thoracoabdominal aorta, in a patient with “mega-aorta syndrome.” A two-stage approach using a valve-sparing aortic root replacement, total arch replacement (stage I elephant trunk), and left carotid-axillary bypass was used to treat the root, proximal-mid arch, and left subclavian aneurysmal pathology. This was followed by a hybrid distal arch/Extent II thoracoabdominal aneurysm repair 3 months later. After 15 months follow-up, the patient remains asymptomatic with an intact repair, no endoleak, and normal ventricular and aortic valve function. This case demonstrates a novel “pan-aortic” hybrid approach for repair of extensive thoracic aortic disease

Insights from Monitoring Aspirin Adherence: A Medication Adherence Cascade Tool

Background: Adherence to recommended medications is a key issue in the care of patients with cardiovascular disease (CVD) and barriers to adherence are well established during the medication adherence cascade, the processes of prescribing, obtaining, taking, and maintaining medication use. Aspirin avoids many of the barriers in the medication adherence cascade as it does not require a prescription (prescribing) and is inexpensive, easily accessible (obtaining), prescribed once-daily (taking) as an over-the-counter medication and is generally perceived by patients as safe (maintaining). The purpose of this paper is to report aspirin adherence and propose the Medication Adherence Cascade Tool to assist clinicians to consider all aspects of medication adherence. Methods: Adherence to aspirin was monitored with an electronic pillbox. Frequency analysis, independent T-tests, and ANOVA were completed on 151 patients with underlying heart failure who were prescribed aspirin within a larger parent study. Chi-square tests were completed to assess differences in baseline demographic characteristics. Findings: Mean aspirin adherence was 82.2% overall, with 11.9% of sample with adherence ≤ 50%, 18.5% with adherence 50–80%, and 69.5% with adherence ≥80%. Greater adherence was observed in self-identified White as compared to Black patients (84.47% vs 73.53%; p = 0.014), and patients ≥70 years of age compared to \u3c70 years (87.00% vs 77.49%; p = 0.009). Interpretation: Aspirin adherence was suboptimal despite the fact that it addresses most of the barriers on the medication adherence cascade (ie, relatively easy access, low cost, and low risk). A Medication Adherence Cascade Tool (MACT) is proposed as a clinical guide to facilitate patient–provider co-production of strategies to address medication adherence. The tool can assist patients and providers to co-produce adherence to achieve optimal medication benefits