Self-thermophoresis of laser-heated spherical Janus particles.

An analytic framework is presented for calculating the self-induced thermophoretic velocity of a laser-heated Janus metamaterial micro-particle, consisting of two conducting hemispheres of different thermal and electric conductivities. The spherical Janus is embedded in a quiescent fluid of infinite expanse and is exposed to a continuous light irradiation by a defocused laser beam. The analysis is carried under the electrostatic (Rayleigh) approximation (radius small compared to wavelength). The linear scheme for evaluating the temperature field in the three phases is based on employing a Fourier-Legendre approach, which renders rather simple semi-analytic expressions in terms of the relevant physical parameters of the titled symmetry-breaking problem. In addition to an explicit solution for the self-thermophoretic mobility of the heated Janus, we also provide analytic expressions for the slip-induced Joule heating streamlines and vorticity field in the surrounding fluid, for a non-uniform (surface dependent) Soret coefficient. For a 'symmetric' (homogeneous) spherical particle, the surface temperature gradient vanishes and thus there is no self-induced thermophoretic velocity field. The 'inner' temperature field in this case reduces to the well-known solution for a laser-heated spherical conducting colloid. In the case of a constant Soret phoretic mobility, the analysis is compared against numerical simulations, based on a tailored collocation method for some selected values of the physical parameters. Also presented are some typical temperature field contours and heat flux vectors prevailing in the two-phase Janus as well as light-induced velocity and vorticity fields in the ambient solute and a new practical estimate for the self-propelling velocity.

Parenting behavior and growth of child conduct problems: Moderation by callous-unemotional traits.

Although positive parenting behavior is central to efficacious interventions for child conduct problems (CP), studies of youth CP have focused mostly on negative parenting behavior. That is, few studies have examined dimensions of positive parenting behavior (e.g., positive reinforcement, involvement) as independent predictors of CP and even fewer have investigated their potential moderation by callous-unemotional (CU) traits. A sample of 184 6-9 year-old children with and without attention-deficit/hyperactivity disorder (ADHD) was followed prospectively for two years. Controlling for baseline ADHD diagnostic status, initial CP, and negative parenting (i.e., corporal punishment), we examined CU traits, positive reinforcement and involvement, and their interactions as predictors of two-year change in CP. Positive reinforcement and CU traits independently predicted increased rule breaking behavior whereas parental involvement inversely predicted aggressive behavior. A significant positive reinforcement x CU traits interaction suggested that positive reinforcement predicted a decrease in aggressive behavior, but only in children with low CU traits; conversely, positively reinforcement marginally predicted increased aggressive behavior among children with high CU traits. No other significant parenting x CU traits interaction was observed. We consider these findings within a developmental psychopathology framework where interactive exchanges underlie the development of CP.

A computational model of ureteral peristalsis and an investigation into ureteral reflux.

The aim of this study is to create a computational model of the human ureteral system that accurately replicates the peristaltic movement of the ureter for a variety of physiological and pathological functions. The objectives of this research are met using our in-house fluid-structural dynamics code (CgLes-Y code). A realistic peristaltic motion of the ureter is modelled using a novel piecewise linear force model. The urodynamic responses are investigated under two conditions of a healthy and a depressed contraction force. A ureteral pressure during the contraction shows a very good agreement with corresponding clinical data. The results also show a dependency of the wall shear stresses on the contraction velocity and it confirms the presence of a high shear stress at the proximal part of the ureter. Additionally, it is shown that an inefficient lumen contraction can increase the possibility of a continuous reflux during the propagation of peristalsis.

Experimental investigation of nonlinear properties of crackle and screech in supersonic jets.

Supersonic crackle, an irritable component of aircraft jet noise, was investigated using model scale measurements. Near-field results showed Gaussian distribution but far-field had high skewness and even higher in its derivative. Skewness, a measure of asymmetry in the waveform, was compared to screech arising from shock associated noise which was also high but in contrast to crackle its skewness derivative had dropped to a much smaller value than its waveform. Both crackle and screech are nonlinear but their nonlinear properties are entirely different. Crackle is quantified when its derivative skewness becomes larger than its waveform skewness which should exceed 0.3.

In-vitro investigation of the hemodynamic responses of the cerebral, coronary and renal circulations with a rotary blood pump installed in the descending aorta.

This study investigates the hemodynamic responses of the cardiovascular system when a rotary blood pump is operating in the descending aorta, with a focus on the cerebral, coronary and renal autoregulation, using our in-house cardiovascular emulator. Several improvements have been made from our previous studies. A novel coronary system was developed to replicate the native coronary perfusion. Three pinch valves actuated by stepper motors were used to simulate the regional autoregulation systems of the native cerebral, coronary and renal circulations. A rotary pump was installed in the descending aorta, in series with the heart, and the hemodynamic responses of the cardiovascular system were investigated with a focus on cerebral, coronary and renal circulation over a wide range of pump rotor speeds. Experiments were performed twice, once with the autoregulation systems active and once with the autoregulation systems inactive, to reflect that there will be some impairment of autoregulatory systems in a patient with heart failure. It was shown that by increasing the rotor speed to 3000 rpm, the cardiac output was improved from 2.9 to 4.1 L/min as a result of an afterload reduction induced by the pressure drop upstream of the pump. The magnitudes of changes in perfusion in the cerebral, coronary and renal circulations were recorded with regional autoregulation systems active and inactive.

Differential Association of Youth Attention-Deficit/Hyperactivity Disorder and Anxiety With Delinquency and Aggression.

Although attention-deficit/hyperactivity disorder (ADHD) is independently associated with both anxiety and conduct problems, it is unclear how co-occurring ADHD + anxiety are associated with different forms of conduct problems. That is, there is relatively little evidence how ADHD and co-occurring anxiety, relative to ADHD only and anxiety only, are associated with aggression and delinquency. Controlling for age, sex, oppositional defiant disorder diagnostic status and total psychopathology, we compared children with anxiety only, ADHD only, ADHD + anxiety, and a clinic-referred comparison group on measures of conduct problems. Three hundred eighty ethnically diverse boys and girls ages 5 to 17 (M = 11.62) were evaluated using a semistructured diagnostic interview for ADHD and anxiety; aggressive and delinquent behavior were evaluated using the Child Behavior Checklist. Children with anxiety only (n = 119) did not differ from clinic-referred comparisons (i.e., no DSM-IV diagnosis; n = 95) on aggression or delinquency; children with ADHD only (n = 130) were significantly more aggressive and delinquent than children with anxiety only. Children with ADHD + anxiety (n = 36) were significantly less aggressive than children with ADHD only, but they did not differ with respect to delinquency. These preliminary data suggest that ADHD, in the presence of anxiety, may be associated with significantly less aggression but not less delinquency. We discuss these findings from a developmental psychopathology framework and stress the need for further study to support possible implications for intervention and prevention.

Association of comorbid anxiety with social functioning in school-age children with and without attention-deficit/hyperactivity disorder (ADHD).

Although attention-deficit/hyperactivity disorder (ADHD) is frequently comorbid with disruptive behavior disorders, less is known about ADHD and comorbid anxiety. To improve understanding about the association of anxiety and social functioning, we studied 223 6 to 9 year-old ethnically diverse boys and girls (M=7.4 years) with and without ADHD. According to parents, children with ADHD and anxiety (n=46) and ADHD only (n=71) were consistently less socially competent than comparison children (i.e., no anxiety and ADHD: n=80) and children with anxiety only (n=26), who did not differ from one another. A similar pattern emerged for teacher ratings where youth with ADHD only and ADHD with anxiety exhibited the most social problems, but they did not differ from each other. These data suggest that comorbid anxiety does not exacerbate social dysfunction among 6 to 9 year-old children with ADHD. We consider findings within a developmental psychopathology framework to further understand social development in children with ADHD and anxiety.

Diagnosis and management of central nervous system histoplasmosis.

Two cases of Histoplasma meningitis are presented, illustrating the difficulty in diagnosis and treatment. The first case occurred in a patient with acquired immunodeficiency syndrome as a relapse of disseminated histoplasmosis and resolved after prolonged treatment and ongoing antiretroviral therapy. The second case occurred in a cardiac allograft recipient as meningitis and focal brain lesions that responded to liposomal amphotericin B, but the patient died shortly after therapy was completed. Unfortunately, there are no prospective studies addressing the diagnosis and management of patients with histoplasmosis of the central nervous system from which to provide evidence-based guidelines for care. In the absence of such data, an approach will be presented on the basis of our experience and opinions.

HCV-coinfection is associated with diabetes and CD4 decline.

In February 2001, Dr. Robert Zackin became the first HIV-infected individual to receive a heart transplant. A biostatistician whose research focus is HIV, Dr. Zackin was the senior author of the paper published in the New England Journal of Medicine summarizing his case and providing 2-year follow-up from his successful transplant (N Engl J Med 2003;348:2323-8). Recently, Dr. Deborah J Cotton spoke with Dr. Zackin about life as both patient and researcher, the controversies surrounding solid-organ transplantation in HIV-infected individuals, and surviving AIDS and advanced cardiomyopathy.

Erroneously low or undetectable plasma human immunodeficiency virus type 1 (HIV-1) ribonucleic acid load, determined by polymerase chain reaction, in West African and American patients with non-B subtype HIV-1 infection.

The polymerase chain reaction (PCR) assay for plasma human immunodeficiency virus type 1 (HIV-1) ribonucleic acid (RNA) inadequately quantitates virus load for some non-B HIV-1 subtypes because of genetic diversity in the gag region targeted by the PCR primers. Unexpectedly low or undetectable plasma HIV-1 RNA findings by PCR were a clue to non-B HIV-1 infections in patients in whom plasma HIV-1 RNA was found to be substantially higher when determined by a branched-chain deoxyribonucleic acid assay.

Detection and significance of splenomegaly on chest radiographs of HIV-infected outpatients.

AIM: The purpose of this study was to determine the prevalence of splenomegaly on chest radiographs of HIV-infected outpatients and to correlate with CD4 cell counts, opportunistic conditions, liver disease and the presence of intrathoracic disease on chest radiographs. METHODS: We reviewed sequential chest radiographs of 200 HIV Clinic outpatients at the Jacobi Medical Center, Bronx, New York, mixed with chest radiographs of 137 outpatients of unknown HIV status (control group) for the presence of splenomegaly and intrathoracic disease. Chest radiographic assessment of splenomegaly was correlated with computed tomography (CT) or ultrasound (US) in 90 out of 337 patients (27%). Clinical charts of all HIV-infected patients were reviewed for CD4 cell count, liver disease and opportunistic conditions including those associated with splenomegaly. The HIV-infected patients were divided into four groups by ascending CD4 cell count: Group 1 (0-50 cells/mm3), Group 2 (51-200 cells/mm3), Group 3 (201-500 cells/mm3) and Group 4 (>500 cells/ mm3). There were 118 men and 82 women with a mean age of 40 (range 20-60) years. Mean CD4 was 180 (range 2-1108) cells/mm3. We also reviewed all autopsies (n = 239) performed on HIV-infected patients between 1983 and 1995 at our institution to correlate splenic size with splenic pathology in that population. RESULTS: Splenomegaly was present on chest radiographs in 82 (41%) HIV-infected patients including: 36/84 (43%) Group 1, 23/49 (47%) Group 2, 18/46 (39%) Group 3, and 5/21 (24%) Group 4 (P = NS). Splenomegaly was present in 30/97 (31%) patients with no evidence of liver disease or opportunistic conditions known to be associated with splenomegaly. Forty-nine HIV-infected patients had 63 opportunistic conditions known to be associated with splenomegaly (mycobacterial and fungal infections, Kaposi sarcoma and lymphoma), half of whom had splenomegaly. Splenomegaly was present on chest radiographs in 18/137 (13%) controls. The presence or absence of splenomegaly on CT or US agreed with chest radiography in 89%. Among the autopsied patients, 135/239 (56%) had splenomegaly (splenic weight > or = 240 g). No specific pathogen was present in 93/135 (69%) enlarged spleens. In contrast, one or more opportunistic conditions were present in 26/104 (25%) normal weight spleens. CONCLUSION: In conclusion, splenomegaly is common in HIV-infected patients and was present in 41% of this series. Splenomegaly may be seen in HIV-infected patients without associated opportunistic conditions or liver disease and in the absence of specific splenic pathology. Chest radiography plays an important role in detecting splenomegaly and may lead to earlier diagnosis of HIV infection.

The case of the undetectable viral load.

AIDS: A case study is presented of an African-American gay man who tested positive for HIV in 1996 after going to a clinic for treatment of fever, mouth ulcers, and a dermatomal vesicular rash. He began treatment, was judged to be adherent to his regimen, and remained well clinically. However, despite a significant virologic response, his CD4 cell count never rose. Since these clinical findings were inconsistent and puzzling, the clinician suspected the man had a variant HIV-1 subtype that was not being measured by the viral load test, the Roche RT-PCR. The viral load testing process is described. This case demonstrates the difficulty in measuring viral load reductions in patients with variant subtypes of HIV-1. Viral load testing remains an important component of treatment management, but clinicians need to be reminded that it is not always accurate.^ieng

Another undectectable viral load: HIV-2.

AIDS: A case study is presented of a pregnant woman from Ghana whose prenatal screening indicated that she was HIV-positive. She was given AZT and 3TC to prevent transmitting the virus to her newborn, but declined to take the drugs, thinking they were unnecessary. The baby tested positive, and further testing of the mother revealed that they were infected with HIV-2, not HIV-1 for which they had been tested. HIV-2 is a lentivirus capable of causing the same clinical syndrome as HIV-1 with regard to CD4-cell depletions and opportunistic infections in some people. HIV-2 is not transmitted as easily via sexual intercourse or childbirth as is HIV-1. Common in West Africa, HIV-2 may be more widely spread than HIV-1. Treatment options for the patient are described.^ieng