2,140 research outputs found
HIV-1 Tat elongates the G1 phase and indirectly promotes HIV-1 gene expression in cells of glial origin
No full textHuman immunodeficiency virus type-1 (HIV-1) infection of the central nervous system (CNS) gives rise to many of the neurological complications in patients with AIDS. Infection of microglial cells and astrocytes in the brain promotes the release of HIV-1 Tat and other candidate neurotoxins that may be associated with the widespread neuropathology. To examine the contribution of HIV-1 Tat to the interplay between virus and CNS cells, the human astrocytic cell line, U-87MG, was treated with recombinant Tat protein. Fluorescence- activated cell sorting analysis indicated that Tat induces a G1 arrest in these cells. Consistent with this observation, lower levels of cyclin E-Cdk2 kinase activity and phosphorylated Rb were detected in the Tat-treated cells compared with the control cells. Interestingly, our observations indicate that the underphosphorylated form of Rb that is prevalent in Tat-treated cells promotes HIV-1 transcription by a mechanism involving the NF-κB enhancer region. Taken together, the data presented here provide the first evidence that the HIV-1 regulatory protein, Tat, may manipulate the host cell cycle to promote viral gene expression. The significance of these findings relates to the current hypothesis that indirect effects of HIV-1 infection of the CNS may contribute to the neurological complications associated with AIDS dementia complex
Atlantic Hurricane Season of 1997
No full textThe 1997 Atlantic hurricane season is summarized and the year's tropical storms, hurricanes, and one subtropical storm are described. The tropical cyclones were relatively few in number, short lived, and weak compared to long-term climatology. Most systems originated outside the deep Tropics. Hurricane Danny was the only system to make landfall. It produced rainfall totals to near 1 m in southern Alabama and is blamed for five deaths. Hurricane Erika was responsible for the season's two other fatalities, in the coastal waters of Puerto Rico.
Corresponding author address: Dr. Edward N. Rappaport, TPC/NHC, 11691 S.W. 17th Street, Miami, FL 33165-2149
Sensitivity, reproducibility, and accuracy in short tandem repeat genotyping using capillary array electrophoresis.
No full textThe Human Genome Initiative has increased significantly the rate at which disease-causing genes are being mapped and sequenced. New cost-effective methods to locate the genes and to characterize disease-causing mutations require robust, reproducible, and accurate protocols for measuring DNA fragment lengths. Capillary array electrophoresis (CAE) offers rapid, high-resolution separations, high throughput, and sensitive detection. To assess the utility of CAE for the accumulation of genetic information, we tested both sizing accuracy and reproducibility using 48-capillary prototype systems. Two multiplex PCR allelic ladder standards and several CA-repeat markers were analyzed in > 100 runs. Reproducibility in typing > 8000 genotypes reveals a standard deviation of less than 0.2 bp on these systems under optimized conditions. However, sequence-dependent migration anomalies were observed at most simple sequence loci even when analyzed under denaturing conditions, resulting in a systematic bias in estimated fragment sizes. We show here that, by normalizing results to known typing controls, one can obtain locus-averaged accuracies of < 0.06 bp and normalized results within 1 bp of actual. We detect as little as a 1:30,000 dilution of a DNA quantitation standard stained with highly sensitive intercalating dyes, indicating an 80-zeptomole sensitivity limit. However, to obtain reproducible electrokinetic injection, approximately 200 attomoles of fluorescein-labeled DNA is required. These sensitivity limits, sizing precision, and accuracy, together with the 1-hr run times for 48-96 samples, indicate that CAE is a viable method for high-throughput genetic analysis of simple sequence repeat polymorphisms
Full-Stack End-to-End mmWave Simulations Using 3GPP and NYUSIM Channel Model in ns-3
No full textAccurate channel modeling and simulation tools are vital for studying sub-THz and millimeter (mmWave) wideband communication system performance. To accurately design future high data rate, low latency wireless modems, the entire protocol stack must be appropriately modeled to understand how the physical layer impacts the end-to-end performance experienced by the end user. This paper presents a full stack end-to-end performance analysis in ns-3 using drop-based NYU channel model (NYUSIM) and 3GPP statistical channel model (SCM) in scenarios, namely urban microcell (UMi), urban macrocell (UMa), rural macrocell (RMa), and indoor hotspot (InH) at 28 GHz with 100 MHz bandwidth. Video data is transmitted at 50 Mbps using User Datagram Protocol (UDP), and we observe that the RMa channel is benign in non-line of sight (NLOS) for NYUSIM and 3GPP SCM as it exhibits no packet drops and yields maximum throughput (48.1 Mbps) and latency of ∼ 20 ms. In NLOS, for NYUSIM, the UMa and RMa channels are similar in terms of throughput and packet drops, and the latency in UMi and InH scenarios is 10 times and 25 times higher respectively compared to UMa. Our results indicate that mmWave bands can support data rates of 50 Mbps with negligible packet drops and latency below 150 ms in all scenarios using NYUSIM
A large deletion encompassing the entire alpha-like globin gene cluster in a family of northern European extraction.
No full textWe describe a new deletional form of alpha thalassemia segregating in three generations of a family of northern European origin. A full-term female girl had hypochromic, microcytic anemia since early infancy associated with delayed language development, slow growth and weight gain. Hematologic studies suggested the presence of alpha thalassemia. Gene-blotting studies showed no abnormal alpha-like globin gene fragments; however, studies of inheritance of informative polymorphic restriction fragments using zeta, alpha and 3'-alpha-hypervariable region (3'-HVR) probes showed evidence for an extensive deletion encompassing the entire alpha-like globin gene cluster. The 3' breakpoint of this deletion maps beyond the 3'-HVR, a region implicated as a hot spot for the generation of other large deletional events within the alpha-like cluster. The 5' breakpoint maps at least 10 kilobases (kb) 5' to the zeta-globin gene. The minimum size estimate for this deletion is greater than 47 kilobases
Public Safety Communications above 6 GHz: Challenges and Opportunities
No full textAdvanced public safety communication (PSC) services call for fast, reliable and low-latency communication technologies, capable of supporting diverse communication modes (aerial, unmanned, vehicular, and peer-To-peer), fast channel dynamics, and ad hoc or mesh structures. For this reason, PSC has been identified as one of the key potential uses cases for the next generation of communication systems, the so-called 5G. In this scenario, the millimeter wave (mmWave) bands and other frequencies above 6 GHz are particularly interesting, since they are largely untapped and offer vastly more spectrum than current cellular allocations in the highly congested bands below 6 GHz, thus enabling orders of magnitude greater data rates and reduced latency. For example, new PSC networks in the mmWave bands could support high-definition video, virtual reality, and other broadband data to large numbers of first responders. Surveillance drones or ambulances could also be provided high-speed connectivity along with machine-Type communication for remotely controlled robotic devices entering dangerous areas. However, the way towards this ambitious goal is hindered by a number of open research challenges. In this paper, after a brief introduction to PSC services and requirements, we illustrate the potential of the frequencies above 6 GHz for PSC and discuss the open problems that need to be solved in order to pave this way. Finally, we describe the main components of a test platform for mmWave systems that is functional to the study of such complex scenarios and that we plan to develop as an invaluable tool for realizing mmWave PSC networks
An integrated approach to biomonitoring exposure to styrene and styrene-(7,8)-oxide using a repeated measurements sampling design
No full textThe aim of this work was to investigate urinary analytes and haemoglobin and albumin adducts as biomarkers of exposure to airborne styrene (Sty) and styrene-(7,8)-oxide (StyOX) and to evaluate the influence of smoking habit and genetic polymorphism of metabolic enzymes GSTM1 and GSTT1 on these biomarkers. We obtained three or four air and urine samples from each exposed worker (eight reinforced plastics workers and 13 varnish workers), one air and urine samples from 22 control workers (automobile mechanics) and one blood sample from all subjects. Median levels of exposure to Sty and StyOX, respectively, were 18.2 mg m(-3) and 133 microg m(-3) for reinforced plastics workers, 3.4 mg m(-3) and 12 microg m(-3) for varnish workers, and <0.3 mg m(-3) and <5 microg m(-3) for controls. Urinary levels of styrene, mandelic acid, phenylglyoxylic acid, phenylglycine (PHG), 4-vinylphenol (VP) and mercapturic acids (M1+M2), as well as cysteinyl adducts of serum albumin (but not those of haemoglobin) were significantly associated with exposure status (controls<exposed workers). Also, levels of VP and M1+M2 were significantly affected by smoking, and levels of M1+M2 were significantly affected by GSTM1 polymorphisms. Multiple linear regression analyses of the subject-specific (logged) metabolite levels across exposed workers showed that Sty was a significant predictor for all urinary analytes while StyOX was a significant predictor of PHG only. Interestingly, the log scale regression coefficients for Sty in these models were significantly less than one for all metabolites except M1+M2. This suggests that the natural scale relationships between levels of all Sty metabolites, except M1+M2, displayed downward concavity with increasing Sty exposure, suggestive of saturable metabolism. Levels of the protein adducts were not associated with exposure to either Sty or StyOX among exposed subjects
A COMPREHENSIVE X-RAY AND MULTIWAVELENGTH STUDY OF THE COLLIDING GALAXY PAIR NGC 2207/IC 2163
No full textWe present a comprehensive study of the total X-ray emission from the colliding galaxy pair NGC 2207/IC 2163, based on Chandra, Spitzer, and GALEX data. We detect 28 ultraluminous X-ray sources (ULXs), 7 of which were not detected previously because of X-ray variability. Twelve sources show significant long-term variability, with no correlated spectral changes. Seven sources are transient candidates. One ULX coincides with an extremely blue star cluster (B – V = –0.7). We confirm that the global relation between the number and luminosity of ULXs and the integrated star-formation rate (SFR) of the host galaxy also holds on local scales. We investigate the effects of dust extinction and age on the X-ray binary (XRB) population on subgalactic scales. The distributions of N [subscript X] and L [subscript X] are peaked at L [subscript IR]/L [subscript NUV] ~ 1, which may be associated with an age of ~10 Myr for the underlying stellar population. We find that approximately one-third of the XRBs are located in close proximity to young star complexes. The luminosity function of the XRBs is consistent with that typical for high-mass XRBs and appears unaffected by variability. We disentangle and compare the X-ray diffuse spectrum with that of the bright XRBs. The hot interstellar medium dominates the diffuse X-ray emission at E [< over ~] 1 keV and has a temperature kT = 0.28[+0.05 over -0.04] keV and intrinsic 0.5-2 keV luminosity of 7.9 X 10[superscript 40] erg s[superscript -1], a factor of ~2.3 higher than the average thermal luminosity produced per unit SFR in local star-forming galaxies. The total X-ray output of NGC 2207/IC 2163 is 1.5 X 10[superscript 41] erg s[superscript -1], and the corresponding total integrated SFR is 23.7 M [subscript ☉] yr[superscript –1].United States. National Aeronautics and Space Administration (Astrophysics Data Analysis Program Grant NNH13CH56C)Chandra X-ray Observatory (U.S.) (Grant GO3-14092A
The effectiveness of homeownership in building household wealth
No full textThe recent economic and financial crisis and the current slow recovery highlight that homeownership plays a critical role in the U.S. economy. The estimated “equivalent rent” implicitly paid by homeowners accounts for more than 8 percent of gross domestic product. Investment in single-family housing also represents a significant share of GDP and is closely tied to the business cycle. During the past decade, such investment has ranged from as little as 1.3 percent of GDP during recessions to as much as 3.4 percent during expansions. The associated large fluctuations in demand for owner-occupied housing play an important role in driving the business cycle. In addition, demand for owner-occupied housing is especially sensitive to intermediate-term real interest rates and hence to inflation and monetary policy expectations. ; Homeownership also plays an important role in determining household saving, which has implications for national saving and investment. Some aspects of homeownership increase household and national saving. For example, renters intending to purchase a home have an incentive to save to make a down payment on their first home. In addition, new homeowners must promise to save far into the future by making monthly mortgage principal payments. On the other hand, homeownership typically requires large house-related payments and so can reduce household cash flows available to invest in financial assets such as stocks and bonds. ; For decades, conventional wisdom has viewed homeownership as an effective way to build household wealth. However, the recent fall in house prices has caused some observers to question this belief. Rappaport examines whether homeownership effectively builds household wealth. He develops an analytical framework to compare the wealth that homeowners have historically accumulated by building equity in their houses with the wealth they could have accumulated by renting an identical house and investing the resulting saved cash flow in stocks and bonds.
The effectiveness of homeownership in building household wealth
No full textThe recent economic and financial crisis and the current slow recovery highlight that homeownership plays a critical role in the U.S. economy. The estimated “equivalent rent” implicitly paid by homeowners accounts for more than 8 percent of gross domestic product. Investment in single-family housing also represents a significant share of GDP and is closely tied to the business cycle. During the past decade, such investment has ranged from as little as 1.3 percent of GDP during recessions to as much as 3.4 percent during expansions. The associated large fluctuations in demand for owner-occupied housing play an important role in driving the business cycle. In addition, demand for owner-occupied housing is especially sensitive to intermediate-term real interest rates and hence to inflation and monetary policy expectations. ; Homeownership also plays an important role in determining household saving, which has implications for national saving and investment. Some aspects of homeownership increase household and national saving. For example, renters intending to purchase a home have an incentive to save to make a down payment on their first home. In addition, new homeowners must promise to save far into the future by making monthly mortgage principal payments. On the other hand, homeownership typically requires large house-related payments and so can reduce household cash flows available to invest in financial assets such as stocks and bonds. ; For decades, conventional wisdom has viewed homeownership as an effective way to build household wealth. However, the recent fall in house prices has caused some observers to question this belief. Rappaport examines whether homeownership effectively builds household wealth. He develops an analytical framework to compare the wealth that homeowners have historically accumulated by building equity in their houses with the wealth they could have accumulated by renting an identical house and investing the resulting saved cash flow in stocks and bonds.
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