754 research outputs found
Aggregating available soil water holding capacity data for crop yield models
The total amount of water available to plants that is held against gravity in a soil is usually estimated as the amount present at -0.03 MPa average water potential minus the amount present at -1.5 MPa water potential. This value, designated available water-holding capacity (AWHC), is a very important soil characteristic that is strongly and positively correlated to the inherent productivity of soils. In various applications, including assessing soil moisture status over large areas, it is necessary to group soil types or series as to their productivity. Current methods to classify AWHC of soils consider only total capacity of soil profiles and thus may group together soils which differ greatly in AWHC as a function of depth in the profile. A general approach for evaluating quantitatively the multidimensional nature of AWHC in soils is described. Data for 902 soil profiles, representing 184 soil series, in Indiana were obtained from the Soil Characterization Laboratory at Purdue University. The AWHC for each of ten 150-mm layers in each soil was established, based on soil texture and parent material. A multivariate clustering procedure was used to classify each soil profile into one of 4, 8, or 12 classes based upon ten-dimensional AWHC values. The optimum number of classes depends on the range of AWHC in the population of oil profiles analyzed and on the sensitivity of a crop to differences in distribution of water within the soil profile
Molecular basis for passive immunotherapy of Alzheimer's disease
Amyloid aggregates of the amyloid-{beta} (A{beta}) peptide are implicated in the pathology of Alzheimer's disease. Anti-A{beta} monoclonal antibodies (mAbs) have been shown to reduce amyloid plaques in vitro and in animal studies. Consequently, passive immunization is being considered for treating Alzheimer's, and anti-A{beta} mAbs are now in phase II trials. We report the isolation of two mAbs (PFA1 and PFA2) that recognize A{beta} monomers, protofibrils, and fibrils and the structures of their antigen binding fragments (Fabs) in complex with the A{beta}(1–8) peptide DAEFRHDS. The immunodominant EFRHD sequence forms salt bridges, hydrogen bonds, and hydrophobic contacts, including interactions with a striking WWDDD motif of the antigen binding fragments. We also show that a similar sequence (AKFRHD) derived from the human protein GRIP1 is able to cross-react with both PFA1 and PFA2 and, when cocrystallized with PFA1, binds in an identical conformation to A{beta}(1–8). Because such cross-reactivity has implications for potential side effects of immunotherapy, our structures provide a template for designing derivative mAbs that target A{beta} with improved specificity and higher affinity
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Secreted Amyloid β-Proteins in a Cell Culture Model Include N-Terminally Extended Peptides That Impair Synaptic Plasticity
Evidence for a central role of amyloid β-protein (Aβ) in the genesis of Alzheimer’s disease (AD) has led to advanced human trials of Aβ-lowering agents. The “amyloid hypothesis” of AD postulates deleterious effects of small, soluble forms of Aβ on synaptic form and function. Because selectively targeting synaptotoxic forms of soluble Aβ could be therapeutically advantageous, it is important to understand the full range of soluble Aβ derivatives. We previously described a Chinese hamster ovary (CHO) cell line (7PA2 cells) that stably expresses mutant human amyloid precursor protein (APP). Here, we extend this work by purifying an sodium dodecyl sulfate (SDS)-stable, ∼8 kDa Aβ species from the 7PA2 medium. Mass spectrometry confirmed its identity as a noncovalently bonded Aβ40 homodimer that impaired hippocampal long-term potentiation (LTP) in vivo. We further report the detection of Aβ-containing fragments of APP in the 7PA2 medium that extend N-terminal from Asp1 of Aβ. These N-terminally extended Aβ-containing monomeric fragments are distinct from soluble Aβ oligomers formed from Aβ1-40/42 monomers and are bioactive synaptotoxins secreted by 7PA2 cells. Importantly, decreasing β-secretase processing of APP elevated these alternative synaptotoxic APP fragments. We conclude that certain synaptotoxic Aβ-containing species can arise from APP processing events N-terminal to the classical β-secretase cleavage site
Early Patient-Triggered Pressure Support Breathing in Mechanically Ventilated Patients with COVID-19 May Be Associated with Lower Rates of Acute Kidney Injury
Alternate methodology for generation and use of key characteristics
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and (S.M.)--Massachusetts Institute of Technology, Sloan School of Management, 1996.Includes bibliographical references (p. 96).Hardware variation reduction is an issue of paramount importance to manufacturing companies in their efforts to reduce cycle time and manufacturing costs. Hardware variation leads to increased rework, and decreased levels of customer satisfaction. The Boeing Company, the leading manufacturer of commercial jet aircraft, in the late 1980's and early 1990's introduced two separate programs to address hardware variation. Advanced Quality Systems (AQS) addressed variation in components from suppliers; Hardware Variability Control (HVC) addressed hardware variation internal to Boeing. One of the tools utilized by both AQS and HVC is the use of Key Characteristics. Key Characteristics are defined at Boeing as "Attributes or features of a material, part, assembly, installation or system in which variation from nominal has the most adverse affect upon fit, performance, or service life." Key characteristics are generated by first identifying the features or requirements of the end product which are of primary importance to the customer. These requirements are then "flowed down" through the different layers of the engineering tree and build plan to determine those attributes or features at the assembly, subassembly, or detail part level which play a critical role in delivering the product level customer requirements. This methodology therefore allows Boeing to focus on those elements of the manufacturing process where hardware variation has the most potential for causing a quality loss in customer satisfaction. Recently a new methodology has been developed at The Massachusetts Institute of Technology. This methodology, named herein as the quad key methodology, expands the classifications for key characteristics to include the designations of product key characteristics, assembly key characteristics, manufacturing key characteristics, and Stat key characteristics. This new methodology was applied to the analysis of the lower gate assembly for the forward entry door for the new 737-X model airplane, currently in the product design stage at Boeing. The research showed that the added designations for keys available under the quadkey methodology offered several advantages over that included under HVC. Additional uses for key characteristics are also discussed outside of their application for the reduction of hardware variation.by Richard E. Seubert.S.M
Retrospective analysis of free temporoparietal fascial flap for defect reconstruction of the hand and the distal upper extremity
Introduction: Soft tissue reconstruction of the hand and distal upper extremity is challenging to preserve the function of the hand as good as possible. Therefore, a thin flap has been shown to be useful. In this retrospective study, we aimed to show the use of the free temporoparietal fascial flap in soft tissue reconstruction of the hand and distal upper extremity. Methods We analysed the outcome of free temporoparietal fascial flaps that were used between the years 2007and 2016 at our institution. Major and minor complications, defect location and donor site morbidity were the main fields of interest. Results: 14 patients received a free temporoparietal fascial flap for soft tissue reconstruction of the distal upper extremity. Minor complications were noted in three patients and major complications in two patients. Total flap necrosis occurred in one patient. Conclusion The free temporoparietal fascial flap is a useful tool in reconstructive surgery of the hand and the distal upper extremity with a low donor site morbidity and moderate rates of major and minor complications
Tiger Sharks Eat Songbirds: Reply
In response to our recent paper (Drymon et al. 2019), Yosef (2019) questions the mechanism proposed to explain interactions between tiger sharks (Galeocerdo cuvier) and migratory songbirds, while offering an alternative mechanism based on a single observation. We appreciate the comments from Yosef and the opportunity to respond
Application of Near Infrared Spectroscopy to Enhance Safety and Individualize Distraction of Severely Contracted Joints in Far-Advanced Dupuytren’s Disease
Background : Slow distraction of contracted joints is a well-established treatment in far-advanced stages of Dupuytren’s disease (DD). To assess finger perfusion and avoid malperfusion, we studied near infrared spectroscopy (NIRS) to evaluate the maximum extent of distraction that would not harm microcirculation to the finger. This technique also allows an optimized treatment in accordance with sufficient blood perfusion during distraction. Methods : Eligible patients with stage IV finger contractures who needed treatment for Dupuytren’s contracture were included and prospectively investigated. The operation was performed with local anaesthesia. First, the Dupuytren strand of the treated finger was dissected in the palm to allow distraction. Under X-ray control, the distraction device was applied. Then, slow distraction of the treated joint was performed to evaluate the finger perfusion. To assess perfusion of the treated finger, NIRS was used to measure tissue oxygen saturation. If impaired finger perfusion was detected, traction was reduced until sufficient oxygen levels and perfusion patterns were reestablished. Results : NIRS was performed after application of the distraction device in seven cases. We treated six male and one female patient (mean age 70 years, range 51–80 years). Rapid distraction resulted in malperfusion of the treated fingers. Using NIRS proved to render reliable and reproducible information on finger perfusion and oxygenation in all seven patients. Conclusions : Application of NIRS enhances safety in the treatment of far-advanced DD finger contractures with an external skeletal distraction device. It is non-invasive, reproducible, easy to use and allows for an individualized adapted distraction velocity.This research received no external funding
Rapid Orthotics for CURE Kenya - Mechanical Design and Official Testing of 3D Printed Sockets
Rapid Orthotics for Cure Kenya (ROCK) collaborates with CURE, a non-profit orthopedic workshop in Kjabe, Kenya, to implement a 3D printing system for manufacturing custom prosthetics and orthotics. The goal is to reduce the production time and cost for the current transtibial sockets being manufactured in the orthotic workshop to give the patients a way to integrate into society and reduce stigma from their communities. The team designed a system for manufacturing transtibial sockets by converting a scan of the residual limb to a digital file customized by the orthopedic technicians and converted to a file to be 3D printed. The team designed a procedure to ensure the safety of the sockets within the constraints and offsets of the ISO 10328 Standard. The standard requires twelve official tests specifying the type and conditions to be conducted for the Ultimate Strength and Static Proof tests. The team has designed a testing rig that interfaces with the Materials Testing System machine at Messiah University to apply the necessary forces according to the complex geometry outlined in the standard. Additionally, research has determined the optimized 3D printing settings to increase the quality and consistency of the sockets. To smoothly institute the system developed in the orthopedic workshop, the team has developed a Training Manual outlining the step-by-step procedure for the system. Using this system, the team completed all twelve tests with a passing socket result which will contribute to determining the steps for next semester and for the summer site team trip.
Funding for this work provided by The Collaboratory for Strategic Partnerships and Applied Research and by The Collaboratory for Strategic Partnerships and Applied Research.https://mosaic.messiah.edu/engr2022/1014/thumbnail.jp
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