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Segment routing for traffic engineering and effective recovery in low-earth orbit satellite constellations

Digital Communications and Networks 2024年第3期10卷 706-715页

作者： Shengyu Zhang Xiaoqian Li Kwan lawrence Yeung Department of electrical and electronic engineering The University of Hong KongHKSARChina National key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of ChinaChengduSichuan611731China

Low-earth Orbit Satellite Constellations(LeO-SCs)provide global,high-speed,and low latency Internet access services,which bridges the digital divide in the remote *** inter-satellite links are not supported in initial deployment(*** Starlink),the communication between satellites is based on ground stations with radio frequency *** to the rapid movement of satellites,this hybrid topology of LeO-SCs and ground stations is time-varying,which imposes a major challenge to uninterrupted service provisioning and network *** this paper,we focus on solving two notable problems in such a ground station-assisted LeO-SC topology,i.e.,traffic engineering and fast reroute,to guarantee that the packets are forwarded in a balanced and uninterrupted ***,we employ segment routing to support the arbitrary path routing in *** solve the traffic engineering problem,we proposed two source routings with traffic splitting algorithms,Delay-Bounded Traffic Splitting(DBTS)and DBTS+,where DBTS equally splits a flow and DBTS+favors shorter ***-lation results show that DBTS+can achieve about 30%lower maximum satellite load at the cost of about 10%more *** guarantee the fast recovery of failures,two fast reroute mechanisms,Loop-Free Alternate(LFA)and LFA+,are studied,where LFA pre-computes an alternate next-hop as a backup while LFA+finds a 2-segment backup *** show that LFA+can increase the percentage of protection coverage by about 15%.

关键词： Fast reroute Low-earth orbit satellite constellation Segment routing Traffic engineering Traffic splitting

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Allogenic stem Cell Transplantation and COVID-19 Antibodies: Mechanistic Insights and Recipient Concerns

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Open Journal of Immunology 2024年第2期14卷 16-32页

作者： Amna Umer Asma Umer Khayam Nasar Khan David lawrence Greene Umm e. Habiba Sabiha Shamim Pak-American Hospital Pvt. Ltd. Islamabad Pakistan R3 Medical Research LLC Scottsdale USA Bello Bio Labs and Therapeutics (SMC) Pvt. Ltd. Islamabad Pakistan Department of Biochemistry Rawalpindi Medical University Rawalpindi Pakistan Bello Bio LLC Scottsdale USA

Collecting umbilical cord stem cells is widely practiced due to its numerous benefits. Over the past decade, umbilical cord stem cells (UCSCs) have shown effectiveness in treating various conditions, such as bone pathologies, neuropsychiatry disorders, hereditary diseases, and metabolic disorders. However, factors like immunization affect the quantity and quality of cord harvesting. Studies suggest that antibodies from the mother pass through the umbilical cord to protect the infant against infections. Cleaning the umbilical cord before stem cell extraction is crucial to maintain sterility and cell integrity. Vaccinating a female donor, including for COVID-19, typically does not directly affect the stem cells. Although vaccines aim to trigger an immunological response, they generally do not affect the donor’s stem cells.

关键词： Vaccination stem Cell Allogeneic COVID Antibodies

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Frontiers of 3D Printing/Additive Manufacturing: from Human Organs to Aircraft Fabrication

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Journal of Materials Science & Technology 2016年第10期32卷 987-995页

作者： lawrence e.Murr Department of Metallurgical Materials and Biomedical Engineering The University of Texas at El Paso W.M.keck Center for 3D Innovation The University of Texas at El Paso

It has been more than three decades since stereolithography began to emerge in various forms of additive manufacturing and 3D printing. Today these technologies are proliferating worldwide in various forms of advanced manufacturing. The largest segment of the 3D printing market today involves various polymer component fabrications, particularly complex structures not attainable by other manufacturing *** printer head systems have also been adapted to selectively print various speciated human cells and special molecules in attempts to construct human organs, beginning with skin and various tissue patches. These efforts are discussed along with metal and alloy fabrication of a variety of implant and bone replacement components by creating powder layers, which are selectively melted into complex forms（such as foams and other open-cellular structures） using laser and electron beams directed by CAD software. efforts to create a ＂living implant＂ by bone ingrowth and eventual vascularization within these implants will be discussed briefly. Novel printer heads for direct metal droplet deposition as in other 3D printing systems are briefly described since these concepts will allow for the eventual fabrication of very large and complex products, including automotive and aerospace structures and components.

关键词： 3D printing/additive manufacturing Laser and electron beam melting Organ printing Organ and implant vascularization Metal droplet printing

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Strategies for creating living, additively manufactured, open-cellular metal and alloy implants by promoting osseointegration,osteoinduction and vascularization: An overview

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Journal of Materials Science & Technology 2019年第2期35卷 231-241页

作者： lawrence e.Murr Department of Metallurgical Materials and Biomedical Engineering The University of Texas at El Paso W.M.keck Center for 3D Innovation The University of Texas at El Paso

Additive manufacturing of porous, open-cellular metal or alloy implants, fabricated by laser or electron beam melting of a powder bed, is briefly reviewed in relation to optimizing biomechanical compatibility by assuring elastic(Young's) modulus matching of proximate bone, along with corresponding pore sizes assuring osseointegration and vasculature development and migration. In addition, associated, requisite compressive and fatigue strengths for such implants are described. Strategies for optimizing osteoblast(bone cell) development and osteoinduction as well as vascularization of tissue in 3 D scaffolds and tissue engineering constructs for bone repair are reviewed in relation to the biology of osteogenesis and neovascularization in bone, and the role of associated growth factors, bone morphogenic proteins, signaling molecules and the like. Prospects for infusing hydrogel/collagen matrices containing these cellular and protein components or surgically extracted intramedullary(bone marrow) concentrate/aspirate containing these biological and cell components into porous implants are discussed, as strategies for creating living implants, which over the long term would act as metal or alloy scaffolds.

关键词： Additive manufacturing Open cellular metal and alloy implants electron beam melting Living implant strategies Vascularization Osseointegration Osteoinduction

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Vascularization in interconnected 3D printed Ti-6Al-4V foams with hydrogel matrix for biomedical bone replacement implants

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Science China Materials 2018年第4期61卷 565-578页

作者： Victor L.Correa Kristine M.Garza lawrence e.Murr Department of Metallurgical Materials and Biomedical Engineering University of Texas at El Paso Department of Biological Sciences University of Texas at El Paso

Vascularization on newly implanted metal orthopedic implants has remained a challenge in the field of tissue engineering. To address this challenge, in this research,an interconnected foam structure of Ti-6 Al-4 V was microfabricated by electron beam melting(eBM) technique. The foam in question has a density of 1.77 g cm-3 with 60% porosity and a tensile strength of 18 GPa. An extracellular matrix based hydrogel was added as an aqueous matrix to the *** mimetic stress has been closely related to many wound healing biomedical applications as it increases survival and proliferation molecular signals. To that end, increased expression of hypoxia-inducible factor-1α(Hif-1α) and vascular endothelial growth factor(VeGF) in the aqueous hydrogel matrix was achieved by the addition of a hypoxia mimetic deferoxamine mesylate(DFM). In this study, the formation of an endothelial network was achieved in a hydrogel matrix in the presence of the before mentioned 3 D printed metal foam. Cellular viability, fluorescent microscopy and scanning electron microscopy imaging analysis demonstrate that pre-osteoblasts undergo proliferation and also attach efficiently to the foam when exposed to DFM. Human umbilical vascular endothelial cells(HUVeCs) were grown in an extracellular matrix-like 3 D hydrogel and a hypoxia-like stress was achieved. This research demonstrates that pre-osteoblast cells undergo cell differentiation and increase the production of hydroxyapatite on exposure to the hypoxia mimetic molecule. This proposed approach encompasses an ideal prototype for a completely living implanted structure for future orthopedic implants.

关键词： Ti-6Al-4V electron beam melting angiogenesis deferoxamine mesylate hydrogel vascularization

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Spatial and temporal dynamics of growth of woody plant species (birch and willows) on the foreland of a retreating glacier in southern Iceland

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ecological Processes 2021年第1期10卷 184-194页

作者： Haley e.Synan Mikael A.Melfi lawrence H.Tanner Department of Biological and environmental Sciences Le Moyne CollegeSyracuseNew York 13214USA

Background:The forelands of retreating glaciers are invaluable natural laboratories in which to explore the processes of primary *** studies have been conducted on foreland chronosequences to identify temporal and spatial trends of the successional *** study focused on the spatio-temporal distribution of three woody plant species on the foreland of a retreating glacier in southern Iceland where historical observations provide precise age control of the *** evaluate colonization and successional trends,we examined which species increase in abundance with time and tested the role of proximity to a seed source in ***,we quantified the rate at which biomass carbon is added to the ***:The density of stems of Betula pubescens increases with moraine age across the foreland chronosequence while the density of stems of both Salix lanata and Salix phylicifolia *** found low statistical significance to the relationship between the density of *** and distance from a forested ridge nor did we find a relationship between the lengths of the stems and the moraine *** biomass increased fastest during early successional stages and reached a maximum of 28.5 g C m^(−2) on the oldest ***:early colonization of moraines was controlled by environmental filters which favored both Salix *** by *** followed as environmental factors,e.g.,favorable soil properties,*** found no conclusive evidence that proximity to a potential source of *** propagules was a significant factor in controlling *** assumption that the abundance of individuals increased with time through later successional stages proved valid for ***,but not for either species of *** findings are consistent with the classical spatial successional model of community ***,general successional processes at the landscape scale control the temp

关键词： Glacial foreland Chronosequence Primary succession Spatial distribution Aboveground biomass Iceland

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The ePSPS Pro106Ser substitution solely accounts for glyphosate resistance in a goosegrass(eleusine indica) population from Tennessee, United States

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Journal of Integrative Agriculture 2016年第6期15卷 1304-1312页

作者： Janel L Huffman Chance W Riggins lawrence e.ste.ke. Patrick J Tranel Department of Crop Sciences University of Illinois Urbana IL 61801 USA Department of Plant Sciences University of Tennessee Jackson TN 38301 USA

Previous studies have documented the occurrence of glyphosate-resistant （GR） goosegrass （eleusine indica （L.） Gaertn.） and, in at least some cases, resistance is due to an altered target site. Research was performed to determine if an altered target site was responsible for GR in a Tennessee, United States goosegrass population （TennGR）. DNA sequencing revealed a mutation in TennGR plants conferring the Prol06Ser 5-enolpyruvylshikimate-3-phosphate synthase （ePSPS） substitution previously identified in other GR populations. F2 populations were derived from TennGR plants crossed with plants from a glyphosate-susceptible population （TennGS） and analyzed for their response to glyphosate and genotyped at the ePSPS locus. Plants from the F2 populations segregated 1：2：1 sensitive：intermediate：resistant in response to a selec- tive dose of glyphosate, and these responses co-segregated with the ePSPS genotypes （PP106, PS106, and SS106）. To separately investigate the effect of the Prol06Ser substitution on GR, glyphosate dose-response curves and 50% effective dose （eDso） values were compared among the three genotypes and the two parental populations. The SS106 genotype was 3.4-fold resistant relative to the PP106 genotype, identical to the resistance level obtained when comparing the resistant and susceptible parental populations. We conclude that the mutation conferring a Prol06Ser ePSPS mutation is solely responsible for GR in the TennGR goosegrass population.

关键词： herbicide resistance monogenic trait glyphosate PCR amplification of specific alleles (PASA) ePSPS target-site mutation

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Foot burns and diabetes: a retrospective study

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Burns & Trauma 2015年第3期3卷 151-154页

作者： e.lawrence F.Li Concord Hospital Burns Unit RhodesAustralia

Background: Diabetes in conjunction with a foot burn can compound the challenges in wound healing;however, the impact of diabetes on outcomes of patients with foot burns has not been examined. Methods: A retrospective notes audit was conducted at the Concord Hospital Burns Unit for patients with foot burns who were admitted from 1st January 2012 to 31st December 2013. Data were collected for 15 subjects with foot burns and diabetes and 18 subjects with foot burns and no diabetes as a control group. Subjects were matched for percentage total body surface area of burns. Results: The mean inpatient and total lengths of stay for the diabetic group were 21.27 days and 64.80 days, which were significantly longer (P = 0.090 and P = 0.054) than the 9.61 days and 30.56 days in the control, based on a significance level of 0.10. The diabetic group was significantly older (P = 0.001), at 56.60 years versus 39.44 years in the control. Significantly (P = 0.033) more patients with diabetes were not working (n = 12/15 or 80.00 % versus n = 7/18 or 38.89 %) compared to the control. The diabetic group had higher rates of regrafting (n = 3/15 or 20.00 % versus n = 1/18 or 5.55 %) than the control and significantly (P = 0.013) more amputations (n = 5/15 or 33.33 % versus n = 0 or 0.00 %) compared to the control. Fewer patients with diabetes were prescribed pressure garments (n = 2/15 or 13.33 % versus n = 9/18 or 50.00 %), which was significant (P = 0.034). The increased age of patients in the diabetic group correlates with results from other studies. Healing time may be reflected by total length of stay, which was more than double for patients with diabetes, increasing demand and cost of inpatient and outpatient services. Conclusion: This study highlights the importance of recognizing the potential for poorer outcomes for patients with diabetes and indicates the need for more burn prevention education and promotion in this 'at risk' patient group.

关键词： Diabetes Foot Burns Age Regrafting Wound healing

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Design　Issues　for　Use　of　Solid　State　Transmitter　Radars　in　the　Terminal　Airspace

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Journal of Systems engineering and electronics 1995年第1期6卷 57-64页

作者： e. Lee Cole & lawrence J. Friz(Westinghouse electric Corporation, Baltimore, MD, USA) Westinghouse electric Corporation Baltimore MD USA

Abstract

关键词： Design Use Issues Airspace

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Dynamic distribution of TTK in HeLa cells: insights from an ultrastructural study

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Cell Research 2003年第6期13卷 443-449页

作者： AKIRA SAWAGeCHI,lawrence BRAKO Department of Molecular and Cell Biology University of California Berkeley CA 94720 USA electron Microscopy Facility Morhouse School of Medicine Atlanta GA 30310 USA

entry into mitosis is driven by signaling cascades of mitotic kinases. Our recent studies show that TTK, a kinetochore-associated protein kinase, interacts with CeNP-e, a mitotic kinesin located to corona fiber of kinetochore. Using immunoelectron microscopy, here we show that TTK is present at the nuclear pore adjacent complex of interphase HeLa cells. Upon nuclear envelope fragmentation, TTK targets to the outermost region of the developing kinetochores of monoorient chromosome as well as to spindle poles. After stable attachment, throughout chromosome congression, TTK is a constituent of the corona fibers, extending up to 90 nm away from the kinetochore outer plate. Upon metaphase alignment, TTK departs from the kinetochore and migrates toward the centrosomes. Taken together, this evidence strongly supports a model in which TTK functions in spindle checkpoint signaling cascades at both kinetochore and centrosome.

关键词： mitosis kinetochore TTK.

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