X-Ray Computed Tomography Instrument Performance Evaluation, Part III: Sensitivity to Detector Geometry and Rotation Stage Errors at Different Magnifications.

With steadily increasing use in dimensional metrology applications, especially for delicate parts and those with complex internal features, X-ray computed tomography (XCT) has transitioned from a medical imaging tool to an inspection tool in industrial metrology. This has resulted in the demand for standardized test procedures and performance evaluation standards to enable reliable comparison of different instruments and support claims of metrological traceability. To meet these emerging needs, the American Society of Mechanical Engineers (ASME) recently released the B89.4.23 standard for performance evaluation of XCT systems. There are also ongoing efforts within the International Organization for Standardization (ISO) to develop performance evaluation documentary standards that would allow users to compare measurement performance across instruments and verify manufacturer's performance specifications. Designing these documentary standards involves identifying test procedures that are sensitive to known error sources. This paper, which is the third in a series, focuses on geometric errors associated with the detector and rotation stage of XCT instruments. Part I recommended positions of spheres in the measurement volume such that the sphere center-to-center distance error and sphere form errors are sensitive to the detector geometry errors. Part II reported similar studies on the errors associated with the rotation stage. The studies in Parts I and II only considered one position of the rotation stage and detector; i.e., the studies were conducted for a fixed measurement volume. Here, we extend these studies to include varying positions of the detector and rotation stage to study the effect of magnification. We report on the optimal placement of the stage and detector that can bring about the highest sensitivity to each error.

Opportunities and Constraints in the Standardization of Geometrical Product Specification.

A key focus of the CIRP CAT 2020 is the role of standardization in GPS specification, and the constraints and opportunities provided by standards throughout the design lifecycle, including in the verification of products. This focus is supported by two Keynote presentations from the chairmen of the ASME and ISO committees that develop standards for the specifications of geometric tolerances. The CIRP CAT conferences provide an opportunity for researchers and practitioners to exchange new ideas and discuss the implications of new and evolving research in the areas of geometrical tolerancing, assembly analysis, modeling of manufacturing processes, and standardization.

Interoperability: linking design and tolerancing with metrology.

On October 30, 2014 the American National Standards Institute (ANSI) approved QIF v 2.0 (Quality Information Framework, version 2.0) as an American National Standard. Subsequently in early 2016 QIF version 2.1 was approved. This paper describes how the QIF standard models the information necessary for quality workflow across the full metrology enterprise. After a brief description of the XML 'language' used in the standard, the paper reports on how the standard enables information exchange among four major activities in the metrology enterprise (product definition; measurement planning; measurement execution; and the analysis and reporting of the quality data).

Substance use and its association with psychiatric symptoms in perinatally HIV-infected and HIV-affected adolescents.

Drug use in combination with psychiatric illness may lead to unsafe sexual risk behavior and increased risk for secondary HIV transmission among adolescents with HIV infection. We compared the prevalence of substance use for perinatally HIV-infected youth to uninfected adolescents living in families affected by HIV infection, and evaluated the association of psychiatric symptoms with risk of substance use. Among 299 adolescents (196 HIV+, 103 HIV-) aged 12-18 years enrolled in IMPAACT P1055, a multisite US cohort study, 14% reported substance use at enrollment (HIV+: 13%, HIV-: 16%). In adjusted logistic regression models, adolescents had significantly higher odds of substance use if they met symptom criteria for ADHD [adjusted odds ratio (aOR) = 2.7, Wald χ(2) = 5.18, P = 0.02], major depression or dysthymia (aOR = 4.0, Wald χ(2) = 7.36, P = 0.01), oppositional defiant disorder (aOR = 4.8, Wald χ(2) = 12.7, P = 0.001), or conduct disorder (aOR = 15.4, Wald χ(2) = 28.12, P = 0.001). Among HIV-infected youth, those with lower CD4 lymphocyte percentage (CD4% < 25%) had significantly increased risk of substance use (aOR = 2.7, Wald χ(2) = 4.79, P = 0.03). However, there was no overall association of substance use with HIV infection status, and the association between psychiatric symptoms and substance use did not differ by HIV status. Programs to prevent substance use should target both HIV-infected and uninfected adolescents living in families affected by HIV infection, particularly those with psychiatric symptoms.

Co-occuring psychiatric symptoms in children perinatally infected with HIV and peer comparison sample.

OBJECTIVE: To compare the rates of psychopathology in youths perinatally infected with HIV (N = 319) with a comparison sample of peers (N = 256) either HIV-exposed or living in households with HIV-infected family members. METHOD: Participants were randomly recruited from 29 sites in the United States and Puerto Rico and completed an extensive battery of measures including standardized DSM-IV-referenced ratings scales. RESULTS: The HIV+ group was relatively healthy (73% with CD4% >25%), and 92% were actively receiving antiretroviral therapy. Youths with HIV (17%) met symptom and impairment criteria for the following disorders: attention-deficit/hyperactivity disorder (12%), oppositional defiant disorder (5%), conduct disorder (1%), generalized anxiety disorder (2%), separation anxiety disorder (1%), depressive disorder (2%), or manic episode (1%). Many youths with HIV (27%) and peers (26%) were rated (either self- or caregiver report) as having psychiatric problems that interfered with academic or social functioning. With the exception of somatization disorder, the HIV+ group did not evidence higher rates or severity of psychopathology than peers, although rates for both groups were higher than the general population. Nevertheless, self-awareness of HIV infection in younger children was associated with more severe symptomatology, and youths with HIV had higher lifetime rates of special education (44 vs 32%), psychopharmacological (23 vs 12%), or behavioral (27 vs 17%) interventions. Youth-caregiver agreement was modest, and youths reported more impairment. CONCLUSION: HIV infection was not associated with differentially greater levels of current psychopathology; nevertheless, investigation of relations with developmental changes and specific illness parameters and treatments are ongoing.

A highly active single-mutation variant of P450BM3 (CYP102A1).

The power of proline: Bold amino acid substitutions in sensitive protein regions are frequently unproductive, while more subtle mutations can be sufficient to bring about dramatic changes. But introducing proline at the residue next to the sulfur ligand in P450(BM3) (CYP102A1) has the unexpected and desirable effect of enhancing the activity of this fatty acid hydroxylase with a broad range of non-natural substrates, as illustrated by the figure.

Ultrafast x-ray Thomson scattering of shock-compressed matter.

Spectrally resolved scattering of ultrafast K-alpha x-rays has provided experimental validation of the modeling of the compression and heating of shocked matter. The elastic scattering component has characterized the evolution and coalescence of two shocks launched by a nanosecond laser pulse into lithium hydride with an unprecedented temporal resolution of 10 picoseconds. At shock coalescence, we observed rapid heating to temperatures of 25,000 kelvin when the scattering spectra show the collective plasmon oscillations that indicate the transition to the dense metallic plasma state. The plasmon frequency determines the material compression, which is found to be a factor of 3, thereby reaching conditions in the laboratory relevant for studying the physics of planetary formation.

Illicit Drug Markets Among New Orleans Evacuees Before and Soon After Hurricane Katrina.

This paper analyzes illicit drug markets in New Orleans before and after Hurricane Katrina and access to drug markets following evacuation at many locations and in Houston. Among New Orleans arrestees pre-Katrina, rates of crack and heroin use and market participation was comparable to New York and higher than in other southern cities. Both cities have vigorous outdoor drug markets. Over 100 New Orleans evacuees provide rich accounts describing the illicit markets in New Orleans and elsewhere. The flooding of New Orleans disrupted the city's flourishing drug markets, both during and immediately after the storm. Drug supplies, though limited, were never completely unavailable. Subjects reported that alcohol or drugs were not being used in the Houston Astrodome, and it was a supportive environment. Outside the Astrodome, they were often approached by or could easily locate middlemen and drug sellers. Evacuees could typically access illegal drug markets wherever they went. This paper analyzes the impact of a major disaster upon users of illegal drugs and the illegal drug markets in New Orleans and among the diaspora of New Orleans evacuees following Hurricane Katrina. This analysis includes data from criminal justice sources that specify what the drug markets were like before this disaster occurred. This analysis also includes some comparison cities where no disaster occurred, but which help inform the similarities and differences in drug markets in other cities. The data presented also include an initial analysis of ethnographic interview data from over 100 New Orleans Evacuees recruited in New Orleans and Houston.

Sustained benefit from a long-term antiretroviral adherence intervention. Results of a large randomized clinical trial.

OBJECTIVE: To assess the efficacy of 2 adherence interventions, medication managers (MM) and medication alarms (ALR), among antiretroviral (ARV)-naive persons with HIV initiating ARV therapy. METHODS: A multicenter, randomized, adherence intervention clinical trial was conducted among participants coenrolled in an HIV ARV strategy study for ARV-naive individuals. Sites were assigned by cluster randomization using a 2 x 2 factorial design to administer MM, ALR, MM + ALR, or neither (control). MM participants received individualized, structured, long-term adherence support from trained MMs. ALR participants received individually programmed ALR alarms for use throughout the study. RESULTS: The 928 participants, followed a median of 30 months, included 22% women and 75% nonwhites; the median baseline CD4 count was 155 cells/mm. First virologic failure was 13% lower in all MM versus no-MM groups (P = 0.13) and 28% lower in MM versus no-MM subgroups randomized to 2-class ARV arms in the parent ARV study (P = 0.01). MM (vs. no-MM) participants had significantly better CD4 cells count (P = 0.01) and adherence (P < 0.001) outcomes. ALR (vs. no-ALR) participants had worse virologic outcomes. CONCLUSION: This large randomized clinical trial demonstrated that interpersonal structured adherence support was associated with improved long-term medication adherence and virologic and immunologic HIV outcomes.

Childhood sexual abuse and age at initiation of injection drug use.

OBJECTIVES: We examined the relation between childhood sexual abuse and injection drug use initiation among young adult injection drug users. METHODS: We used mixed effect linear models to compare age at first injection among 2143 young injection drug users by first sexual abuse age categories. RESULTS: The participants were predominantly male (63.3%) and White (52.8%). Mean age and age at first injection were 23.7 and 19.6 years, respectively; 307 participants (14.3%) reported childhood sexual abuse. After adjustment for gender, race/ethnicity, noninjection drug use before first injection drug use, and recruitment site, childhood sexual abuse was independently associated with younger age at first injection. CONCLUSIONS: Childhood sexual abuse was associated with earlier initiation of injection drug use. These data emphasize the need to integrate substance abuse prevention with postvictimization services for children and adolescents.

Prevalence and correlates of crack-cocaine injection among young injection drug users in the United States, 1997-1999.

OBJECTIVES: We estimated prevalence and identified correlates of crack-cocaine injection among young injection drug users in the United States. METHODS: We analyzed data from the second Collaborative Injection Drug Users Study (CIDUS II), a 1997-1999 cohort study of 18-30-year-old, street-recruited injection drug users from six US cities. RESULTS: Crack-cocaine injection was reported by 329 (15%) of 2198 participants. Prevalence varied considerably by site (range, 1.5-28.0%). No participants injected only crack-cocaine. At four sites where crack-cocaine injection prevalence was greater than 10%, recent (past 6 months) crack-cocaine injection was correlated with recent daily injection and sharing of syringes, equipment, and drug solution. Lifetime crack-cocaine injection was correlated with using shooting galleries, initiating others into drug injection, and having serologic evidence of hepatitis B virus and hepatitis C virus infection. CONCLUSIONS: Crack-cocaine injection may be a marker for high-risk behaviors that can be used to direct efforts to prevent HIV and other blood-borne viral infections.

Association between injection practices and duration of injection among recently initiated injection drug users.

BACKGROUND: Earlier studies suggest higher infection risk among recently initiated injection drug users (IDUs) than more experienced users. Whether IDUs' risky injection practices rise progressively with duration of injection or frequency of practices is higher near initiation and then taper remains an open question. METHODS: Recently initiated IDUs were street recruited and interviewed between 1997 and 1999 as part of a multisite cohort study in five US urban cities. Recent risky injection practices (injecting with others and injecting on average more now) were examined across three cross-sections defined by duration of injection: 0-1 year, 2-3 years, and 4-6 years. RESULTS: The IDU groups of <2 years duration (n = 691) and 2-3 years duration (n = 697) had higher odds than the 4-6 year group (n = 520) of reporting injecting with others (Odds Ratio, OR = 1.52, and OR = 1.47, respectively) and injecting on average more now (OR = 1.44 and OR = 1.44, respectively). The associations remained after multivariate adjustment for demographic variables. CONCLUSIONS: These data on recently initiated IDUs suggest that risky injection practices were more frequent earlier than later within the first 6 years of initiation, emphasizing that outreach prevention needs to identify and intervene with IDUs early.

Direct experimental evidence of back-surface ion acceleration from laser-irradiated gold foils.

Au foils were irradiated with a 100-TW, 100-fs laser at intensities greater than 10(20) W/cm2 producing proton beams with a total yield of approximately 10(11) and maximum proton energy of >9 MeV. Removing contamination from the back surface of Au foils with an Ar-ion sputter gun reduced the total yield of accelerated protons to less than 1% of the yield observed without removing contamination. Removing contamination from the front surface (laser-interaction side) of the target had no observable effect on the proton beam. We present a one-dimensional particle-in-cell simulation that models the experiment. Both experimental and simulation results are consistent with the back-surface acceleration mechanism described in the text.

Optical parametric chirped-pulse amplifier as an alternative to Ti:sapphire regenerative amplifiers.

We demonstrated a high-pulse energy, femtosecond-pulse source based on optical parametric chirped-pulse amplification. We successfully amplified 1-microm broadband oscillator pulses to 31 mJ and recompressed them to 310-fs pulse duration, at a 10-Hz repetition rate. The gain in our system is 6 x 10(7), achieved by the single passing of only 40 mm of gain material pumped by a commercial Q-switched Nd:YAG laser. This relatively simple system replaces a more complex Ti:sapphire regenerative-amplifier-based chirped-pulse amplification system. Numerous features in design and performance of optical parametric chirped-pulse amplifiers make them a preferred alternative to regenerative amplifiers based on Ti:sapphire in the front end of high-peak-power lasers.

Reported adherence as a determinant of response to highly active antiretroviral therapy in children who have human immunodeficiency virus infection.

OBJECTIVE: The complexity of highly active antiretroviral therapy (HAART), with multiple medications, formulations, and dosing intervals, makes adherence challenging. Little is known about the adherence of children to HAART. The objective of this study was to identify correlates of adherence to HAART and the relationship between adherence and study outcomes in a pediatric clinical trial. METHODS: Pediatric AIDS Clinical Trials Group 377 is a phase I/II randomized trial of 4 HAART regimens in antiretroviral-experienced, clinically stable children aged 4 months to 17 years. The 4 treatment arms include various 3- or 4-drug combinations of d4T, 3TC, nevirapine, ritonavir, and nelfinavir. After informed consent was obtained, 193 children were enrolled between December 1997 and September 1998. Questionnaires were developed to collect subject- or caregiver-reported adherence to study medications and to identify problems associated with medication administration. Every 3 months, the number of doses of each medication missed during the 3 days preceding the study visit was recorded. Full adherence (FA) and non-full adherence were defined as missing no doses and missing at least 1 dose, respectively. RESULTS: Adherence data from study week 48 or the most recent study visit were available for 125 children (week 48 for 109 children). Overall, 70% of children reported FA and 30% reported non-full adherence. Adherence did not differ by treatment arm, age, or the child's knowledge of his or her human immunodeficiency virus infection status. There was a suggestion that adherence was less for white than nonwhite children (40% vs 73% FA) and did not differ between black and Hispanic children. Rates of FA were 82% for d4T, 79% for 3TC, 83% for nevirapine, 84% for ritonavir, and 68% for nelfinavir. Despite the similar rates of FA, difficulties with taking specific medications were reported most frequently for ritonavir and nelfinavir. These included poor taste, patient refusal, and scheduling problems. Adherence was associated with the virologic response: FA was seen in 92% of children with > or =2 log10 drop in viral load and in 64% with <2 log10 drop in viral load. CONCLUSION: In children, reported adherence predicts the virologic response to HAART therapy and is a useful measure of adherence. Interventions and regimens to increase adherence to HAART should result in an improved outcome.