5,363 research outputs found
Collagenous bone matrix-induced endochondral ossification hemopoiesis.
Transplantation of collagenous matrix from the rat diaphyseal bone to subcutaneous sites resulted in new bone formation by an endochondral sequence. Functional bone marrow develops within the newly formed ossicle. On day 1, the implanted matrix was a discrete conglomerate with fibrin clot and polymorphonuclear leukocytes. By day 3, the leukocytes disappeared, and this event was followed by migration and close apposition of fibroblast cell surface to the collagenous matrix. This initial matrix-membrane interaction culminated in differentiation of fibroblasts to chondroblasts and osteoblasts. The calcification of the hypertrophied chondrocytes and new bone formation were correlated with increased alkaline phosphatase activity and 45Ca incorporation. The ingrowth of capillaries on day 9 resulted in chondrolysis and osteogenesis. Further remodelling of bony trabeculae by osteoclasts resulted in an ossicle of cancellous bone. This was followed by emergence of extravascular islands of hemocytoblasts and their differentiation into functional bone marrow with erythropoietic and granulopoietic elements and megakaryocytes in the ossicle. The onset and maintenance of erythropoiesis in the induced bone marrow were monitored by 59Fe incorporation into protein-bound heme. These findings imply a role for extracellular collagenous matrix in cell differentiation
Calculating adiabatic evolution of the perturbed DNLS/MNLS solitons
A symbolic computation technique is developed to calculate adiabatic
evolution equations for parameters of the perturbed DNLS/MNLS solitons obtained
by the recently developed direct perturbation theory [X.-J. Chen and J. Yang,
Phys. Rev. E {\bf 65}, 066608(2002)]. Effects of the intrapulse Raman
scattering, third-order group velocity dispersion, and narrow-banded filters
with nonlinear gain on the MNLS solitons are studied as examples.Comment: 10 pages, 1 figure. to be published on Phys. Lett.
Determining Training Needs for Cloud Infrastructure Investigations using I-STRIDE
As more businesses and users adopt cloud computing services, security
vulnerabilities will be increasingly found and exploited. There are many
technological and political challenges where investigation of potentially
criminal incidents in the cloud are concerned. Security experts, however, must
still be able to acquire and analyze data in a methodical, rigorous and
forensically sound manner. This work applies the STRIDE asset-based risk
assessment method to cloud computing infrastructure for the purpose of
identifying and assessing an organization's ability to respond to and
investigate breaches in cloud computing environments. An extension to the
STRIDE risk assessment model is proposed to help organizations quickly respond
to incidents while ensuring acquisition and integrity of the largest amount of
digital evidence possible. Further, the proposed model allows organizations to
assess the needs and capacity of their incident responders before an incident
occurs.Comment: 13 pages, 3 figures, 3 tables, 5th International Conference on
Digital Forensics and Cyber Crime; Digital Forensics and Cyber Crime, pp.
223-236, 201
Solar cycle variation in solar f-mode frequencies and radius
Using data from the Global Oscillation Network Group (GONG) covering the
period from 1995 to 1998, we study the change with solar activity in solar
f-mode frequencies. The results are compared with similar changes detected from
the Michelson Doppler Imager (MDI) data. We find variations in f-mode
frequencies which are correlated with solar activity indices. If these changes
are due to variation in solar radius then the implications are that the solar
radius decreases by about 5 km from minimum to maximum activity.Comment: To appear in Solar Physic
Articulation and growth of skeletal elements in balanid barnacles (Balanidae, Balanomorpha, Cirripedia)
The morphology and ultrastructure of the shells of two balanid
species have been examined, paying special attention to the
three types of boundaries between plates: (i) radii-parietes, (ii)
alae-sheaths, and (iii) parietes-basal plate. At the carinal
surfaces of the radii and at the rostral surfaces of the alae, there
are series of crenulations with dendritic edges. The crenulations
of the radius margins interlock with less prominent features
of the opposing paries margins, whereas the surfaces of the
longitudinal abutments opposing the ala margins are
particularly smooth. The primary septa of the parietes also
develop dendritic edges, which abut the internal surfaces of
the primary tubes of the base plates. In all cases, there are
chitino-proteinaceous organic membranes between the abutting
structures. Our observations indicate that the very edges of the
crenulations and the primary septa are permanently in contact
with the organic membranes. We conclude that, when a new
growth increment is going to be produced, the edges of both
the crenulations and the primary septa pull the viscoelastic
organic membranes locally, with the consequent formation of
viscous fingers. For the abutting edges to grow, calcium
carbonate must diffuse across the organic membranes, but it is
not clear how growth of the organic membranes themselves is
accomplished, in the absence of any cellular tissue.This research was funded by projects CGL2017-85118-P (A.G.C., C.S. and C.G.) and CGL2015-64683-P (A.B.R.N.)
of the Spanish Ministerio de Economía, Industria y Competitividad, the Unidad Científica de Excelencia UCE-PP2016-05
of the University of Granada (A.G.C. and A.B.R.N.) and the Research Group RNM363 of the Junta de Andalucía
(A.G.C.). N.A.L. acknowledges support from CONICYT-Chile through grant nos. FONDECYT 1140938, PCI REDES
170106 and PIA ANILLOS ACT172037, for international collaborative research with A.G.C. and A.B.R.N
HLA-DRB1 shared epitope genotyping using the revised classification and its association with circulating autoantibodies, acute phase reactants, cytokines and clinical indices of disease activity in a cohort of South African rheumatoid arthritis patients
INTRODUCTION: The revised shared epitope (SE) concept in rheumatoid arthritis (RA) is based on the presence (S) or
absence (X) of the SE RAA amino acid motif at positions 72 to 74 of the third hypervariable region of the various
human leucocyte antigen (HLA)-DRB1 alleles. The purpose of this study was to investigate SE subtypes on the basis
of the American College of Rheumatology 1987 revised criteria for the classification of RA in a cohort of South
African RA patients (n = 143) and their association with clinical and circulating biomarkers of disease activity
(autoantibodies, acute phase reactants and cytokines).
METHODS: Genomic DNA was analysed using high-resolution recombinant sequence-specific oligonucleotide PCR
typing of the HLA-DRB1 allele. Subtypes of the SE were classified according to the amino acids at positions 72 to
74 for the RAA sequence, and further sub-divided according to the amino acids at positions 70 and 71, which
either contribute to (S2, S3P), or negate (S1, S3D) RA susceptibility. Disease activity was assessed on the basis of (1)
Disease Activity Score in 28 joints using C-reactive protein (CRP), (2) rheumatoid factor (RF), (3) CRP and (4) serum
amyloid A by nephelometry, anticyclic citrullinated peptide antibodies (aCCP) by an immunofluorometric
procedure, and cytokines by multiplex bead array technology.
RESULTS: Of the 143 RA patients, 81 (57%) were homozygous (SS) and 50 (35%) were heterozygous (SX) for the SE
alleles with significant overexpression of S2 and S3P (respective odds ratios (ORs) 5.3 and 5.8; P < 0.0001), and 12
(8%) were classified as no SE allele (XX). Both the SS and SX groups showed a strong association with aCCP
positivity (OR = 10.2 and P = 0.0010, OR = 9.2 and P = 0.0028, respectively) relative to the XX group. Clinical scores
and concentrations of the other biomarkers of disease activity (RF, CRP and T helper cell type 1 (Th1), Th2,
macrophage and fibroblast cytokines) were also generally higher in the SS group than in the SX and XX groups.
CONCLUSIONS: RA susceptibility alleles investigated according to revised criteria for the classification of RA were
significantly increased in South African RA patients and strongly associated with aCCP in particular as well as with
circulating cytokines and disease severity.The Connective Tissue Diseases Research Fund, University of the
Witwatersrandhttp://arthritis-research.com/content/13/5/R16
Vertical hydraulic conductivity of a clayey-silt aquitard: accelerated fluid flow in a centrifuge permeameter compared with in situ conditions
This discussion paper is a preprint. It has been under review for the journal Hydrology and Earth System Sciences (HESS). The revised manuscript was not accepted.Evaluating the possibility of leakage through low permeability geological strata is critically important for sustainable water supplies, extraction of fuels from strata such as coal beds, and confinement of waste within the earth. Characterizing low or negligible flow rates and transport of solutes can require impractically long periods of field or laboratory testing, but is necessary for evaluations over regional areas and over multi-decadal timescales. The current work reports a custom designed centrifuge permeameter (CP) system, which can provide relatively rapid and reliable hydraulic conductivity (K) measurement compared to column permeameter tests at standard gravity (1g). Linear fluid velocity through a low K porous sample is linearly related to g-level during a CP flight unless consolidation or geochemical reactions occur. The CP module is designed to fit within a standard 2 m diameter, geotechnical centrifuge with a capacity for sample dimensions of 30 to 100 mm diameter and 30 to 200 mm in length. At maximum RPM the resultant centrifugal force is equivalent to 550g at base of sample or a total stress of ~2 MPa. K is calculated by measuring influent and effluent volumes. A custom designed mounting system allows minimal disturbance of drill core samples and a centrifugal force that represents realistic in situ stress conditions is applied. Formation fluids were used as influent to limit any shrink-swell phenomena which may alter the resultant K value. Vertical hydraulic conductivity (Kv) results from CP testing of core from the sites in the same clayey silt formation varied (10−7 to 10−9 m s−1, n = 14) but higher than 1g column permeameter tests of adjacent core using deionized water (10−9 to 10−11 m s−1, n = 7). Results at one site were similar to in situ Kv values (3 × 10−9 m s−1) from pore pressure responses within a 30 m clayey sequence in a homogenous area of the formation. Kv sensitivity to sample heterogeneity was observed, and anomalous flow via preferential pathways could be readily identified. Results demonstrate the utility of centrifuge testing for measuring minimum K values that can contribute to assessments of geological formations at large scale. The importance of using realistic stress conditions and influent geochemistry during hydraulic testing is also demonstrated.Australian Research CouncilNational Water Commissio
Two-soliton solution for the derivative nonlinear Schr\"odinger equation with nonvanishing boundary conditions
An explicit two-soliton solution for the derivative nonlinear Schr\"odinger
equation with nonvanishing boundary conditions is derived, demonstrating
details of interactions between two bright solitons, two dark solitons, as well
as one bright soliton and one dark soliton. Shifts of soliton positions due to
collisions are analytically obtained, which are irrespective of the bright or
dark characters of the participating solitons.Comment: 11 pages, 4 figures. Phys. Lett. A 2006 (in press
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