RESUMEN
This paper discusses the changes in the 2016 (third edition) of International Standard ISO 1. While the value of the standard reference temperature remains unchanged at 20 °C, the important definitions for the "reference temperature" and "standard reference temperature," absent in prior editions, are now defined, with the latter exclusively reserved for the assignment of the internationally agreed upon temperature of 20 °C. The scope of the revised Standard has been carefully refined and made more explicit. This, together with other clarifications and improvements, has eliminated the ambiguities associated with specifications at non-standard reference temperatures and allows, if needed, different reference temperatures to be associated with different properties of a workpiece. The relationship between ISO 1 and dimensional measurements is also discussed and clarified. In this paper, we discuss the motivation for these changes and present several issues debated during the revision process for the benefit of future standards committees that might study this topic.
RESUMEN
Human milk contains many bioactive components, including secretory IgA, oligosaccharides, and milk-associated proteins. We assessed the antiviral effects of several components of milk against mammalian reoviruses. We found that glucocerebroside (GCB) inhibited the infectivity of reovirus strain type 1 Lang (T1L), whereas gangliosides GD3 and GM3 and 3'-sialyllactose (3SL) inhibited the infectivity of reovirus strain type 3 Dearing (T3D). Agglutination of erythrocytes mediated by T1L and T3D was inhibited by GD3, GM3, and bovine lactoferrin. Additionally, α-sialic acid, 3SL, 6'-sialyllactose, sialic acid, human lactoferrin, osteopontin, and α-lactalbumin inhibited hemagglutination mediated by T3D. Using single-gene reassortant viruses, we found that serotype-specific differences segregate with the gene encoding the viral attachment protein. Furthermore, GD3, GM3, and 3SL inhibit T3D infectivity by blocking binding to host cells, whereas GCB inhibits T1L infectivity post-attachment. These results enhance an understanding of reovirus cell attachment and define a mechanism for the antimicrobial activity of human milk.
Asunto(s)
Proteínas de la Cápside/inmunología , Orthoreovirus Mamífero 3/inmunología , Orthoreovirus Mamífero 3/patogenicidad , Leche Humana/inmunología , Orthoreovirus de los Mamíferos/inmunología , Orthoreovirus de los Mamíferos/patogenicidad , Polisacáridos/inmunología , Animales , Proteínas de la Cápside/genética , Bovinos , Femenino , Gangliósido G(M3)/inmunología , Gangliósidos/inmunología , Genes Virales , Células HeLa , Pruebas de Inhibición de Hemaglutinación , Interacciones Huésped-Patógeno/inmunología , Humanos , Células L , Orthoreovirus Mamífero 3/clasificación , Orthoreovirus Mamífero 3/genética , Ratones , Leche Humana/virología , Oligosacáridos/inmunología , Orthoreovirus de los Mamíferos/clasificación , Orthoreovirus de los Mamíferos/genética , Infecciones por Reoviridae/inmunología , Infecciones por Reoviridae/prevención & control , Infecciones por Reoviridae/virología , Serotipificación , Especificidad de la Especie , Acoplamiento ViralRESUMEN
Current microscopy-based approaches for immunofluorescence detection of viral infectivity are time consuming and labor intensive and can yield variable results subject to observer bias. To circumvent these problems, we developed a rapid and automated infrared immunofluorescence imager-based infectivity assay for both rotavirus and reovirus that can be used to quantify viral infectivity and infectivity inhibition. For rotavirus, monolayers of MA104 cells were infected with simian strain SA-11 or SA-11 preincubated with rotavirus-specific human IgA. For reovirus, monolayers of either HeLa S3 cells or L929 cells were infected with strains type 1 Lang (T1L), type 3 Dearing (T3D), or either virus preincubated with a serotype-specific neutralizing monoclonal antibody (mAb). Infected cells were fixed and incubated with virus-specific polyclonal antiserum, followed by an infrared fluorescence-conjugated secondary antibody. Well-to-well variation in cell number was normalized using fluorescent reagents that stain fixed cells. Virus-infected cells were detected by scanning plates using an infrared imager, and results were obtained as a percent response of fluorescence intensity relative to a virus-specific standard. An expected dose-dependent inhibition of both SA-11 infectivity with rotavirus-specific human IgA and reovirus infectivity with T1L-specific mAb 5C6 and T3D-specific mAb 9BG5 was observed, confirming the utility of this assay for quantification of viral infectivity and infectivity blockade. The imager-based viral infectivity assay fully automates data collection and provides an important advance in technology for applications such as screening for novel modulators of viral infectivity. This basic platform can be adapted for use with multiple viruses and cell types.
Asunto(s)
Automatización/métodos , Técnica del Anticuerpo Fluorescente/métodos , Procesamiento de Imagen Asistido por Computador/métodos , Reoviridae/patogenicidad , Rotavirus/patogenicidad , Virología/métodos , Línea Celular , HumanosRESUMEN
Accurate measurement of internal magnetic field direction using motional Stark effect (MSE) polarimetry in the edge pedestal is desired for nearly all tokamak scenario work. A newly installed 500 kHz 32-channel digitizer on the MSE diagnostic of DIII-D allows full spectral information of the polarimeter signal to be recovered for the first time. Fourier analysis of this data has revealed magnetohydrodynamic (MHD) fluctuations in the plasma edge pedestal at ρ ≥ 0.92. By correlating edge localized mode fluctuations seen on lock-in amplifier outputs with MSE spectrograms, it has been shown that edge pedestal tearing mode fluctuations cause interference with MSE second harmonic instrument frequencies. This interference results in unrecoverable errors in the real-time polarization angle measurement that are more than an order of magnitude larger than typical polarimeter uncertainties. These errors can cause as much as a 38% difference in local q. By using a redundant measure of the linear polarization found at the fourth harmonic photo-elastic modulator (PEM) frequency, MHD interference can be avoided. However, because of poorer signal-to-noise the fourth harmonic signal computed polarization angle shows no improvement over the MHD polluted second harmonics. MHD interference could be avoided in future edge pedestal tokamak polarimeters by utilizing PEMs with higher fundamental frequencies and a greater separation between their frequencies.
RESUMEN
The use of lock-in amplifiers for phase sensitive detection of motional Stark effect (MSE) diagnostic signals is of critical importance to real-time internal current profile measurements in tokamak plasmas. A digital lock-in (DLI) upgrade utilizing field programable gate array firmware has been installed on the MSE system of the DIII-D tokamak for the eventual replacement of largely obsolete analog units. While the new digital system has shown a small reduction in electronic noise over the analog, the main advantages are reduced cost, hardware simplicity, compact size, and phase tracking during plasma operations. DLI recovery of MSE polarization angles was accomplished through use of reference processing to produce only photoelastic modulator (PEM) second harmonic frequencies and electronic signal processing to maximize the fidelity of the recovered signal. A simplified discrete analytical solution was found that accurately describes the new DLI hardware. The DLI algorithm was found to cause a prohibitively large oscillating artifact atop the demodulated signal. The artifact was caused by the accumulator interval not containing an exact integer number of PEM multiplier periods. Successful MSE measurements require the minimization of this oscillating artifact amplitude. The analytical solution was used to select an appropriate accumulator interval that both reduces the artifact and maintains the greatest temporal resolution possible. Sample EFIT equilibria reconstructions and corresponding safety factor profiles showed very close agreement between the analog and digital lock-ins.
RESUMEN
We present the first ultrafast temporally, spectrally, and angularly resolved x-ray scattering measurements from shock-compressed matter. The experimental spectra yield the absolute elastic and inelastic scattering intensities from the measured density of free electrons. Laser-compressed lithium-hydride samples are well characterized by inelastic Compton and plasmon scattering of a K-alpha x-ray probe providing independent measurements of temperature and density. The data show excellent agreement with the total intensity and structure when using the two-species form factor and accounting for the screening of ion-ion interactions.
RESUMEN
We present K-alpha x-ray Thomson scattering from shock compressed matter for use as a diagnostic in determining the temperature, density, and ionization state with picosecond resolution. The development of this source as a diagnostic as well as stringent requirements for successful K-alpha x-ray Thomson scattering are addressed. Here, the first elastic and inelastic scattering measurements on a medium size laser facility have been observed. We present scattering data from solid density carbon plasmas with >1x10(5) photons in the elastic peak that validate the capability of single shot characterization of warm dense matter and the ability to use this scattering source at future free electron lasers and for fusion experiments at the National Ignition Facility (NIF), LLNL.
RESUMEN
A high-resolution ion Doppler spectrometer (IDS) has been installed on the sustained spheromak plasma experiment to measure ion temperatures and plasma flow. The system is composed of a 1 m focal length Czerny-Turner spectrometer with a diffraction grating line density of 2400 lines/mm, which allows for first order spectra between 300 and 600 nm. A 16-channel photomultiplier tube detection assembly combined with output coupling optics provides a spectral resolution of 0.0126 nm/channel. We calculate in some detail the mapping of curved slit images onto the linear detector array elements. This is important in determining the wavelength resolution and setting the optimum vertical extent of the slit. Also, because of the small wavelength window of the IDS, a miniature fiber-optic survey spectrometer sensitive to a wavelength range 200-1100 nm and having a resolution of 0.2 nm is used to obtain a time-integrated spectrum for each shot to verify specific impurity line radiation. Several measurements validate the systems operation. Doppler broadening of C III 464.72 nm line in the plasma shows time-resolved ion temperatures up to 250 eV for hydrogen discharges, which is consistent with neutral particle energy analyzer measurements. Flow measurements show a sub-Alfvenic plasma flow ranging from 5 to 45 kms for helium discharges.
RESUMEN
BACKGROUND: Hepatitis C virus (HCV) has emerged as a major public health problem among injection drug users. In this analysis we examine whether disinfection of syringes with bleach has a potentially protective effect on anti-HCV seroconversion. METHODS: We conducted a nested case-control study comparing 78 anti-HCV seroconverters with 390 persistently anti-HCV seronegative injection drug users. These data come from the Second Collaborative Injection Drug Users Study, a prospective cohort study that recruited injection drug users from five U.S. cities between 1997 and 1999. We used conditional logistic regression to determine the effect of bleach disinfection of syringes on anti-HCV seroconversion. RESULTS: Participants who reported using bleach all the time had an odds ratio (OR) for anti-HCV seroconversion of 0.35 (95% confidence interval = 0.08-1.62), whereas those reporting bleach use only some of the time had an odds ratio of 0.76 (0.21-2.70), when compared with those reporting no bleach use. CONCLUSIONS: These results suggest that bleach disinfection of syringes, although not a substitute for use of sterile needles or cessation of injection, may help to prevent HCV infection among injection drug users.
Asunto(s)
Desinfección , Hepatitis C/prevención & control , Hepatitis C/transmisión , Abuso de Sustancias por Vía Intravenosa/complicaciones , Jeringas/efectos adversos , Adulto , Estudios de Casos y Controles , Femenino , Hepatitis C/epidemiología , Anticuerpos contra la Hepatitis C/sangre , Humanos , Masculino , Compartición de Agujas , Oportunidad Relativa , Abuso de Sustancias por Vía Intravenosa/sangre , Estados UnidosRESUMEN
We have shown that the HIV-1 laboratory strain NL4-3 that contains P236L [a reverse transcriptase mutation conferring resistance to the nonnucleoside reverse transcriptase inhibitor (NRTI) delavirdine] replicates more slowly than wild-type NL4-3. Other NNRTI-resistance mutations, such as K103N and Y181C, do not reduce the replication capacity of NL4-3 as much as P236L and develop more frequently in HIV-1 isolates from patients failing delavirdine. However, a minority of patients on delavirdine therapy still have isolates with P236L. We postulated that reverse transcriptase (RT) sequences from these patient isolates contain other mutations that compensate for the adverse effect of P236L. To test this hypothesis, we created 15 chimeric NL4-3 isolates that contained delavirdine-resistant RT sequences derived from eight patient isolates and characterized their replication kinetics. Nine of 10 patient-derived clones containing P236L replicated as slowly as NL4-3 with P236L. In contrast, three of five clones that did not have P236L (but had either K103N or Y181C) replicated significantly better than NL4-3 with P236L. Thus, the majority of patients who acquire P236L during delavirdine therapy do not have RT mutations that compensate for the replication defect conferred by P236L. We hypothesize that HIV-1 isolates with P236L may have a compensatory mutation outside RT. Alternatively, variants of HIV-1 with reduced replication fitness may be selected during antiretroviral therapy, suggesting that stochastic events rather than viral replication fitness may determine which drug-resistant mutants emerge early during antiretroviral failure. In some isolates, it appears that the background RT sequence can contribute significantly to the replication fitness of drug-resistant HIV-1 variants.
Asunto(s)
Fármacos Anti-VIH/farmacología , Delavirdina/farmacología , Infecciones por VIH/virología , Transcriptasa Inversa del VIH/genética , VIH-1/enzimología , Inhibidores de la Transcriptasa Inversa/farmacología , Replicación Viral , Fármacos Anti-VIH/uso terapéutico , Línea Celular , Delavirdina/uso terapéutico , Farmacorresistencia Microbiana , VIH-1/efectos de los fármacos , VIH-1/genética , VIH-1/fisiología , Humanos , Inhibidores de la Transcriptasa Inversa/uso terapéutico , Replicación Viral/genéticaRESUMEN
This study examines father-child contact in inner-city African American families with maternal HIV infection. Participants were 246 African American women, 40% of whom are infected with HIV, and one of their non-infected children. Children from non-infected families were more likely to have fathers who are alive and who are living in the home. In addition, regardless of whether or not the father lived in the home, these children had more frequent father contact than children from families with maternal HIV infection. Explanations and implications of the findings are discussed.
Asunto(s)
Negro o Afroamericano , Infecciones por VIH/etnología , Privación Paterna/etnología , Adolescente , Adulto , Recuento de Linfocito CD4 , Estudios de Casos y Controles , Distribución de Chi-Cuadrado , Niño , Relaciones Padre-Hijo/etnología , Femenino , Infecciones por VIH/inmunología , Infecciones por VIH/psicología , Humanos , Masculino , Persona de Mediana Edad , Estados Unidos , Población UrbanaRESUMEN
Telomeres are the ends of linear eukaryotic chromosomes. To ensure that no large stretches of uncharacterized DNA remain between the ends of the human working draft sequence and the ends of each chromosome, we would need to connect the sequences of the telomeres to the working draft sequence. But telomeres have an unusual DNA sequence composition and organization that makes them particularly difficult to isolate and analyse. Here we use specialized linear yeast artificial chromosome clones, each carrying a large telomere-terminal fragment of human DNA, to integrate most human telomeres with the working draft sequence. Subtelomeric sequence structure appears to vary widely, mainly as a result of large differences in subtelomeric repeat sequence abundance and organization at individual telomeres. Many subtelomeric regions appear to be gene-rich, matching both known and unknown expressed genes. This indicates that human subtelomeric regions are not simply buffers of nonfunctional 'junk DNA' next to the molecular telomere, but are instead functional parts of the expressed genome.
Asunto(s)
Genoma Humano , Telómero , Cromosomas Artificiales Bacterianos , Cromosomas Artificiales de Levadura , Proyecto Genoma Humano , HumanosRESUMEN
A 260-kb half-YAC clone derived from human chromosome 1q was mapped at high resolution using cosmid subclone fingerprint analysis and was integrated with overlapping clones from the telomeric end of a separately derived 1q44 BAC contig to create a sequence-ready map extending to the molecular telomere of 1q. Analysis of 100 kb of sample sequences from across the 260-kb region encompassed by the half-YAC revealed the presence of EST sequence matches corresponding to 12 separate Unigene clusters and to 12 separate unclustered EST sequences. Low-copy subtelomeric repeats typical of many human telomere regions are present within the distal-most 30 kb of 1q. The previously isolated and radiation hybrid-mapped markers Bda84F03, 1QTEL019, and WI11861 localized at distances approximately 32, 88, and 99 kb, respectively, from the 1q terminus. This sequence-ready map permits high-resolution integration of genetic maps with the DNA sequences directly adjacent to the tip of human chromosome 1q and will enable telomeric closure of the human chromosome 1q DNA reference sequence by connecting the molecular 1q telomere to an internal BAC contig.
Asunto(s)
Cromosomas Humanos Par 1/genética , Mapeo Contig , Análisis de Secuencia de ADN , Telómero/genética , Cromosomas Artificiales Bacterianos , Cromosomas Artificiales de Levadura , Cósmidos , Dermatoglifia del ADN , Etiquetas de Secuencia Expresada , Humanos , Datos de Secuencia MolecularRESUMEN
OBJECTIVE: Mothers living with HIV face a complex set of child-rearing decisions, often within the context of many competing stressors. One difficult decision for HIV-infected mothers is whether to disclose their HIV status to their children. The purpose of this study is to provide information to HIV-affected families and the professionals working with them as they approach disclosure-related decisions. METHODS: Eighty-seven HIV-infected African American mothers and one of their children who was not HIV-infected were separately interviewed on two occasions. Mothers reported whether they disclosed their HIV status to the child and provided their assessment of the child's functioning. Children also completed an assessment of their functioning. RESULTS: Results revealed that less than one-third of mothers disclosed their HIV status to their children. Disclosure was associated with mother's income level and perceived severity of physical symptoms. In addition, children disclosed to were more often older and female. Contrary to expectation, disclosure was not related to child functioning. CONCLUSIONS: Professionals should note the low rate of disclosure among these families. In the absence of conclusive data regarding impact on child functioning, professionals must remain aware of the complexity of disclosure-related decisions when working with HIV-affected families, particularly in terms of the family and cultural milieu within which families operate.
Asunto(s)
Salud de la Familia , Infecciones por VIH/psicología , Relaciones Madre-Hijo , Revelación de la Verdad , Adulto , Negro o Afroamericano/psicología , Niño , Conducta Infantil/psicología , Recolección de Datos , Salud de la Familia/etnología , Femenino , Humanos , Masculino , Relaciones Madre-Hijo/etnología , MuestreoRESUMEN
This study examined the role of family variables in child resiliency within a sample of African-American, inner-city children whose mothers are HIV-infected. Variables from three dimensions of the family were included: family structural variables, maternal variables, and mother-child (parenting) variables. The participants were 82 children between the ages of 6 and 11 and their HIV-infected mothers. Correlational analyses indicated that resiliency was associated only with three parenting variables: parent-child relationship, parental monitoring, and parental structure in the home. Hierarchical regression analyses indicated a multiplicative relationship between parental monitoring and parent-child relationship and between parental monitoring and parental structure in the home, suggesting that parenting variables potentiate each other. Clinical implications of the findings are considered.
Asunto(s)
Negro o Afroamericano/psicología , Hijo de Padres Discapacitados/psicología , Familia/psicología , Infecciones por VIH/psicología , Desarrollo de la Personalidad , Población Urbana , Adaptación Psicológica , Niño , Femenino , Humanos , Masculino , Relaciones Madre-Hijo , Responsabilidad Parental/psicología , Determinación de la Personalidad , Medio SocialRESUMEN
The role of religious activity in the psychosocial adjustment of 205 inner-city African-American women, one-half of whom are HIV infected, was examined. Those who were HIV infected reported praying more but viewed prayer as less effective in coping with a chronic illness. Frequency of prayer predicted optimism about the future, whereas religious activity was not related to current depressive symptoms.
Asunto(s)
Adaptación Psicológica , Negro o Afroamericano/psicología , Infecciones por VIH/psicología , Religión , Ajuste Social , Síndrome de Inmunodeficiencia Adquirida/psicología , Adolescente , Adulto , Depresión/psicología , Femenino , Infecciones por VIH/etnología , Humanos , Persona de Mediana Edad , Apoyo SocialRESUMEN
This study assesses the prevalence of specific traumatic stressors that meet criterion A for the Diagnostic and Statistical Manual of Mental Disorders' (DSM-IV) diagnosis of posttraumatic stress disorder (PTSD) and symptoms of PTSD in a representative sample of HIV-infected women. The study also assesses the impact of these stressors and symptoms on the clinical progression of HIV infection. The Life Stressor Checklist and the Impact of Events Scale-Revised were administered via interview to 67 Africa-American women beyond the initial stages of HIV infection. The ratio of CD4 t-cells to CD8 t-cells were abstracted from medical records at dates that approximated psychological interviews and were examined at two points in time 12 to 14 months apart. The prevalence of traumatic stressors and PTSD symptoms were high among HIV-infected women. Traumatic stressors were significantly associated with a lower CD4 to CD8 ratio at the 1-year follow-up. Among women who reported a traumatic event, those who also met criteria for PTSD evidenced a lower CD4 to CD8 ratio at the follow-up assessment. The study concludes that prevention and treatment efforts targeted at HIV-infected women must take into account traumatic stressors and PTSD symptoms and their potential impact on the course of the disease.
Asunto(s)
Infecciones por VIH/psicología , Trastornos por Estrés Postraumático , Adolescente , Adulto , Negro o Afroamericano , Relación CD4-CD8 , Niño , Femenino , Estudios de Seguimiento , Infecciones por VIH/inmunología , Humanos , Entrevista Psicológica , Estudios Longitudinales , Estado Civil , Persona de Mediana Edad , Análisis de Regresión , Factores Sexuales , Factores Socioeconómicos , Trastornos por Estrés Postraumático/diagnóstico , Trastornos por Estrés Postraumático/etiología , Factores de TiempoRESUMEN
The development and correlates of 82 inner-city African-American children's coping strategies were examined across three years. Results indicated no change in the mean frequency of self-reported coping strategies over the three years, and a significant correlation of emotion-focused strategies with increased self- and mother-reported behavior problems. Child-reported externalizing problems (and, to a lesser degree, internalizing problems) predicted changes in coping strategies across assessments.
Asunto(s)
Adaptación Psicológica , Negro o Afroamericano/psicología , Trastornos de la Conducta Infantil/psicología , Población Urbana , Adulto , Niño , Femenino , Humanos , Estudios Longitudinales , Masculino , Ajuste Social , Estados UnidosRESUMEN
This study has two purposes: (1) to describe the characteristics related to the transition to orphanhood for children whose mothers die from AIDS and (2) to examine the psychosocial adjustment of these children at six months following maternal death. Twenty orphans and a control sample of 40 children from the same neighbourhoods, as well as their mothers or care-givers, served as participants. Two assessments occurred: (1) prior to the death of the mother in the orphan group and (2) six months after her death. The results indicated that relatives, particularly maternal grandparents, became the new care-giver of the orphans, no more than one residential move had occurred following the mother's death, and the new care-givers were providing a stable home environment. Child psychosocial adjustment did not change following maternal death.