The monoids of orders eight,nine &; ten

We describe the use of symbolic algebraic computation allied with AI search techniques, applied to the problem of the identification, enumeration and storage of all monoids of order ten or less. Our approach is novel, using computer algebra to break symmetry and constraint satisfaction search to find candidate solutions. We present new results in algebraic combinatorics: up to isomorphism and anti-isomorphism, there are 858,977 monoids of order eight; 1,844,075,697 monoids of order nine and 52,991,253,973,742 monoids of order ten.     

A tractable Scheme implementation

Scheme 48 is an implementation of the Scheme programming language constructed with tractability and reliability as its primary design goals. It has the structural properties of large, compiler-based Lisp implementations: it is written entirely in Scheme, is bootstrapped via its compiler, and provides numerous language extensions. It controls the complexity that ordinarily attends such large Lisp implementations through clear articulation of internal modularity and by the exclusion of features, optimizations, and generalizations that are of only marginal value.     

Hospital controls versus community controls: differences in inferences regarding risk factors for hip fracture

In cranioplasty complexity is proportional to the size of the detect, particularly if greater than 50 cm2. If the patient's own bone flap is not available, allogenic frozen bone graft can be used instead. Between June 1990 and June 1995 twenty cranioplasties with allogenic frozen bone grafts were performed. Age of patients ranged between 23 and 63 years (average 38.4 years). Male/female ratio was 2:1.7. Size of craniectomy ranged between 65 and 150 cm2 (average 83.3 cm2). Follow-up ranged between 10 and 58 months (average 41 months). Donors were tested to rule out transmissible diseases, infections, sepsis and/or cancer. Bone grafts were removed under aseptic conditions, microbiological cultures were taken, wrapped in a gauze soaked with Gentamicin sulphate and Bacitracin, sealed in three sterilised vinyl plastic bags, and stored in a deep freezer for a minimum of 30 days (range 36-93 days, average 67 days), at a temperature of -80 degrees C. Grafts were placed in the defect after a step was carved on its borders to facilitate the contact between host and graft. Vancomycin 1 g. IV/12 hours and Ceftriaxone 1 g. IV/12 hours were administered for five days. Grafts were covered by means of scalp flaps. Only one required a musculocutaneous free flap. None was exposed, extruded or had to be removed. Plain skull X-ray studies showed progressive remodelling of the grafts. Partial resorption was observed in two (2/20, 10%) and loss of thickness in another 3/20 (15%), but with no changes in the contour. Biopsies were taken in 3/20 (15%) cases at a second surgical procedure. Areas of osteoclastic resorptive activity mixed with others of osteoblastic bone apposition, showed replacement with new bone. We conclude that cranial vault frozen allografts are a good alternative to autologous bone when the latter is absent or not present in sufficient amount.     

Structural basis of Bcl-xL recognition by a BH3-mimetic α/β-peptide generated by sequence-based design

The crystal structure of a complex between the prosurvival protein Bcl-x(L) and an α/β-peptide 21-mer is described. The α/β-peptide contains six β-amino acid residues distributed periodically throughout the sequence and adopts an α-helix-like conformation that mimics the bioactive shape of the Puma BH3 domain. The α/β-peptide forms all of the noncovalent contacts that have previously been identified as necessary for recognition of the prosurvival protein by an authentic BH3 domain. Comparison of our α/β-peptide:Bcl-x(L) structure with structures of complexes between native BH3 domains and Bcl-2 family proteins reveals how subtle adjustments, including variations in helix radius and helix bowing, allow the α/β-peptide to engage Bcl-x(L) with high affinity. Geometric comparisons of the BH3-mimetic α/β-peptide with α/β-peptides in helix-bundle assemblies provide insight on the conformational plasticity of backbones that contain combinations of α- and β-amino acid residues. The BH3-mimetic α/β-peptide displays prosurvival protein-binding preferences distinct from those of Puma BH3 itself, even though these two oligomers have identical side-chain sequences. Our results suggest origins for this backbone-dependent change in selectivity.     

建筑环境综合康复治疗——来自CO建筑师事务所的医疗建筑设计全方位思考

随着医疗卫生科技、交付以及偿付方式等领域的不断发展,医疗建筑的创新势在必行。作为医院、研究型实验室以及科学健康教育设施设计领域的先行者,CO建筑师事务所采取的是一套整体、全方位的医疗卫生建筑设计方法     

Molecular Engineering of Mesogenic Constituents Within Liquid Crystalline Elastomers to Sharpen Thermotropic Actuation

Liquid crystalline elastomers (LCE) are stimuli-responsive materials with a distinguished mechanical response. LCE have been subject to numerous recent functional examinations in robotics, health sciences, and optics. The liquid crystallinity of the elastomeric polymer networks of LCE are largely derived from liquid crystalline monomer precursors. Recent reports have utilized commercially available liquid crystalline diacrylate monomers in chain extension reactions to prepare LCE. These reactions have been largely based on monomeric precursors originally to enhance the and thermal stability of optical films. Here, it is demonstrated that preparing LCE via a liquid crystalline diacrylate with reduced mesogen–mesogen interaction enhances and sharpens the thermotropic actuation of these materials. Robust composition-response correlations are demonstrated in LCE prepared by three common synthetic methods. The enhanced thermotropic response of LCE prepared from this precursor increases the thermomechanical efficiency by sixfold. Accordingly, this work addresses important limitations in utilizing the thermal response of LCE in robotics, health care, and consumer goods.     

Discovery of Six Ramoplanin Family Gene Clusters and the Lipoglycodepsipeptide Chersinamycin**

Ramoplanins and enduracidins are peptidoglycan lipid intermediate II-binding lipodepsipeptides with broad-spectrum activity against methicillin- and vancomycin-resistant Gram-positive pathogens. Targeted genome mining using probes from conserved sequences within the ramoplanin/enduracidin biosynthetic gene clusters (BGCs) was used to identify six microorganisms with BGCs predicted to produce unique lipodepsipeptide congeners of ramoplanin and enduracidin. Fermentation of Micromonospora chersina yielded a novel lipoglycodepsipeptide, called chersinamycin, which exhibited good antibiotic activity against Gram-positive bacteria (1–2 μg/mL) similar to the ramoplanins and enduracidins. The covalent structure of chersinamycin was determined by NMR spectroscopy and tandem mass spectrometry in conjunction with chemical degradation studies. These six new BGCs and isolation of a new antimicrobial peptide provide much-needed tools to investigate the fundamental aspects of lipodepsipeptide biosynthesis and to facilitate efforts to produce novel antibiotics capable of combating antibiotic-resistant infections.     

Distracted driving in elderly and middle-aged drivers

Automobile driving is a safety-critical real-world example of multitasking. A variety of roadway and in-vehicle distracter tasks create information processing loads that compete for the neural resources needed to drive safely. Drivers with mind and brain aging may be particularly susceptible to distraction due to waning cognitive resources and control over attention. This study examined distracted driving performance in an instrumented vehicle (IV) in 86 elderly (mean = 72.5 years, SD = 5.0 years) and 51 middle-aged drivers (mean = 53.7 years, SD = 9.3 year) under a concurrent auditory–verbal processing load created by the Paced Auditory Serial Addition Task (PASAT). Compared to baseline (no-task) driving performance, distraction was associated with reduced steering control in both groups, with middle-aged drivers showing a greater increase in steering variability. The elderly drove slower and showed decreased speed variability during distraction compared to middle-aged drivers. They also tended to “freeze up”, spending significantly more time holding the gas pedal steady, another tactic that may mitigate time pressured integration and control of information, thereby freeing mental resources to maintain situation awareness. While 39% of elderly and 43% of middle-aged drivers committed significantly more driving safety errors during distraction, 28% and 18%, respectively, actually improved, compatible with allocation of attention resources to safety critical tasks under a cognitive load.