bluuebunny/crossref_metadata_2025_split huggingface dataset:
Freezing method affects the concentration and variability of urine proteins and the interpretation of data on microalbuminuria
Authors: Schultz C. J. , Dalton R. N. , Turner C. , Neil H. A. W. , Dunger D. B. , Group For The Oxford Regional Prospective Study 
Published: July 2002

Summary Aims Microalbuminuria and, to a lesser extent, renal tubular proteins are widely used in the early detection of incipient nephropathy in diabetes mellitus. Recent reports have indicated detrimental effects of storage at −20°C on urine proteins. This study investigated the effects of storage on the measurement of urine proteins and discusses implications for the interpretation of data. Methods Two‐hundred and sixty‐eight specimens, collected from children with Type 1 diabetes, split into duplicate aliquots and stored at −20°C and −70°C, respectively, for 6–8 months, were analysed for albumin, retinol binding protein, N‐acetyl glucosaminidase and creatinine, in the same assays to eliminate inter‐assay variability. Two independent non‐diabetic cohorts of children provided urine specimens, which were stored at −20°C for one cohort and −70°C for the other, to determine normal ranges for urine proteins. Results Storage at −20°C led to a variable underestimation of all three urine proteins in 20% of specimens. Creatinine was unaffected. This underestimation was greater in more concentrated urine (r2 = 0.38, P < 0.001, n = 262). Consequently storage at −20°C increased the variance of the albumin/creatinine ratio more than the variance of albumin concentration. Temperature of storage affected the normal range, which was 0.1–2.1 mg/mmol at −20°C compared to 0.3–3.1 mg/mmol at −70°C. The prevalence of microalbuminuria (> 2
sd above the geometric mean in non‐diabetic specimens stored at −20°C) was 27% after storage at −70°C vs. 24% after − 20°C. The prevalence of microalbuminuria (> 2
sd above the geometric mean in non‐diabetic specimens stored at −70°C) was 21% after storage at −70°C vs. 17% after −20°C. Conclusions Urine proteins are significantly but variably underestimated after storage at − 20 °C. These effects account for increased variance and differences in the normal range, but have less effect on the detection of microalbuminuria than might be predicted.
Oculomotor functions and late‐onset myopia
Authors: Jiang Bai‐chuan , Morse Stephen E. 
Published: July 2002

SummaryIn order to elucidate the role of optical defocus in the development of late‐onset myopia (LOM), we employed both theoretical and experimental approaches. In the theoretical study, which has been reported previously, we suggested a model in which an accommodative sensory operator was added to simulate the sensory part of the accommodation system. Results derived from the model showed that the sensory part might increase the system’s threshold to the accommodative error (or defocus) signal. In this study, we measured the perceptual depth‐of‐focus and the system’s threshold to the defocus signal for three refractive error groups: emmetropic (Emm), stable myopic (S.M.), and progressing myopic (P.M.). Results show that there are no significant differences in the perceptual depth‐of‐focus among the three groups. However, the defocus threshold values of the P.M. group are significantly higher than the values of the other two groups. This result in combination with our previous findings, leads us to suggest that individuals susceptible of developing myopia from sustained near‐work have a specific oculomotor risk profile. Although we are still trying to determine the specific sequence of changes among dark‐focus, AC/A ratio, the accommodative system’s defocus threshold, and refractive error, we are convinced that the changes of oculomotor parameters underlie the type of myopia associated with near‐work.
The Role of Vigabatrin in Childhood Seizure Disorders: Results from a Clinical Audit
Authors: Prasad Asuri N. , Penney S. , Buckley David J. 
Published: July 2002

Summary:  Purpose: The emergence of visual field defects attributed to vigabatrin (VGB) treatment and intramyelinic edema in animal experiments has raised concerns about its future role in the treatment of childhood seizures.Methods: We evaluated our experience with this antiepileptic agent with retrospective analysis of database and chart audit.Results: Of 73 patients, 43 girls and 33 boys were treated with VGB over a 7‐year period. The mean age of patients at the introduction of VGB was 87 months (range, 5–257 months). In 12 of 73 cases, VGB was used as monotherapy; in 61 of 73 cases, it was used as an add‐on drug. Seizure types included secondarily generalized seizures (21), mixed seizures (21), partial seizures (18), and generalized seizures (13). Seizure etiology was idiopathic/cryptogenic in 22 patients, symptomatic in 50, and undetermined in a single patient. The mean duration of therapy was 16 months (median, 10 months; range, 1–144 months). VGB was effective in 30 (seven seizure free, 23 with >90% reduction in seizures), partially effective in four (50–90% reduction in seizures), and ineffective in 38 (<50% reduction in seizures). Nearly 50% of patients with infantile spasms responded to VGB. All patients underwent ophthalmic evaluation; two (16%) of 12 patients who could undergo static threshold perimetry were demonstrated to have the characteristic visual field constriction.Conclusions: VGB is effective in producing a significant reduction in seizure frequency in nearly half the patients with childhood seizures, including refractory epilepsy. Despite emerging concerns regarding visual side effects, this drug retains an important role in the medical management of childhood epilepsy.
A Self‐Paced Step Test to Predict Aerobic Fitness in Older Adults in the Primary Care Clinic
Authors: Petrella Robert J. , Koval John J. , Cunningham David A. , Paterson Donald H. 
Published: July 2002

OBJECTIVES: To study the potential usefulness of a submaximal self‐paced step test as a prediction of maximal aerobic capacity (VO2max) in older adults in the primary care setting.DESIGN: Data were collected during a prospective randomized study of an exercise program.SETTING: Four university family medical clinics in London, Ontario, Canada.PARTICIPANTS: A random sample of 240 healthy older (≥65) men (n = 118) and women (n = 122) from four family medical clinics underwent self‐paced step testing in the clinic with a family physician (n = 16), and step testing and a maximal exercise treadmill test with measurement of respired gases in an exercise laboratory. Testing was done in random order (clinic/laboratory) separated by 2 weeks and then repeated at 52 weeks, following introduction of an exercise program. Relationships between outcome variables were examined by Pearson correlation coefficients while prediction of VO2max was examined using multivariate regression analysis. Cross‐validation with 30 age‐matched hypertensive and 40 age‐matched post‐hip arthroplasty patients was used to test the accuracy of the predictive models.MEASUREMENTS: Measured VO2max, predicted VO2max, step test time, step test heart rate, body mass index (BMI), and O2 pulse.RESULTS: Two hundred women (n = 108) and men (n = 92) completed both the initial and 52‐week assessments. Stepping time, heart rate, age, BMI, and O2 pulse were strongly associated with VO2max for both a normal and a fast step pace and were chosen to develop the predictive model. Normal step‐pace correlation with VO2max (ml/kg/min) was no different (female 0.93: male 0.91) from fast pace (0.95:0.90) with no difference between clinic and laboratory measurement at baseline or 52 weeks. Cross‐validation showed no significant difference from the main group using the predictive model.CONCLUSIONS: The self‐paced step test is a safe and simple clinical instrument that strongly and reliably predicts VO2max, is sensitive to change, and is generalizable in the family practice setting among community‐dwelling older adults differing in fitness and health status.
Prescription Duration After Drug Copay Changes in Older People: Methodological Aspects
Authors: Schneeweiss Sebastian , Maclure Malcolm , Soumerai Stephen B. 
Published: July 2002

OBJECTIVES:Impact assessment of drug benefits policies is a growing field of research that is increasingly relevant to healthcare planning for older people. Some cost‐containment policies are thought to increase noncompliance. This paper examines mechanisms that can produce spurious reductions in drug utilization measures after drug policy changes when relying on pharmacy dispensing data. Reference pricing, a copayment for expensive medications above a fixed limit, for angiotensin‐converting enzyme (ACE) inhibitors in older British Columbia residents, is used as a case example.DESIGN:Time series of 36 months of individual claims data. Longitudinal data analysis, adjusting for autoregressive data.SETTING:Pharmacare, the drug benefits program covering all patients aged 65 and older in the province of British Columbia, Canada.PARTICIPANTS:All noninstitutionalized Pharmacare beneficiaries aged 65 and older who used ACE inhibitors between 1995 and 1997 (N = 119,074).INTERVENTION:The introduction of reference drug pricing for ACE inhibitors for patients aged 65 and older.MEASUREMENTS:Timing and quantity of drug use from a claims database.RESULTS:We observed a transitional sharp decline of 11%± a standard error of 3% (P = .02) in the overall utilization rate of all ACE inhibitors after the policy implementation; five months later, utilization rates had increased, but remained under the predicted prepolicy trend. Coinciding with the sharp decrease, we observed a reduction in prescription duration by 31% in patients switching to no‐cost drugs. This reduction may be attributed to increased monitoring for intolerance or treatment failure in switchers, which in turn led to a spurious reduction in total drug utilization. We ruled out the extension of medication use over the prescribed duration through reduced daily doses (prescription stretching) by a quantity‐adjusted analysis of prescription duration.CONCLUSION:The analysis of prescription duration after drug policy interventions may provide alternative explanations to apparent short‐term reductions in drug utilization and adds important insights to time trend analyses of drug utilization data in the evaluation of drug benefit policy changes. J Am Geriatr Soc 50:521–525, 2002.
HIV Infection: Treatment Outcomes in Older and Younger Adults
Authors: Wellons Melissa Fair , Sanders Linda , Edwards Lloyd J. , Bartlett John A. , Heald Alison E. , Schmader Kenneth E. 
Published: July 2002

OBJECTIVES:To determine the effect of antiretroviral therapy (ART) on the immunological and virological outcomes of older human immunodeficiency virus (HIV)‐infected patients compared with younger HIV‐infected patients.DESIGN:Matched (1:2) retrospective case‐control study (1993–1999).SETTING:Duke University Infectious Diseases Clinic.PARTICIPANTS:One hundred one older patients, mean age 56.7 (range 50–79) and 202 younger patients, mean age 32.8 (range 21–39). Patients were matched on baseline CD4+ cell count and date of clinic entry.MEASUREMENTS:The virological and immunological outcomes were viral suppression (HIV ribonucleic acid (RNA) level ≤400 copies/ml) and change in CD4+ cell count. To estimate differences in antiretroviral drug exposure, the percentage of patients on ART overall and by drug class was compared. To assess antiretroviral drug exposure further, the percentage of patients having interruptions in ART was compared.RESULTS:The older and younger groups had similar baseline CD4+ cell counts (332 vs 306 cells/mm3; P = .31) and similar increases in CD4+ cell counts (+3.47 vs +4.60 cells/mm3/month; P = .37) over a mean ± standard deviation of 2.4 ± 1.7 years of follow‐up. The older group had a higher percentage of patients with current plasma HIV RNA levels less than 400 (46% vs 34%; P = .05). The groups had similar rates of non‐nucleoside reverse transcriptase, nucleoside reverse transcriptase, and protease inhibitor use. The older group had fewer interruptions in ART than the younger group (11% vs 26%; P = .01).CONCLUSIONS:Older HIV‐infected patients responded well to ART, with a significantly greater percentage achieving a current plasma HIV RNA below detectable limits. Older patients experienced similar increases in CD4+ cell count as younger matched controls. Older patients were less likely to interrupt ART, which suggests better adherence and/or tolerance and may explain the higher rate of HIV RNA suppression. J Am Geriatr Soc 50:603–607, 2002.
Arrhenius parameters and the compensation effect in crystallization and diffusion in amorphous Si:H(F) in the presence or absence of metal contacts
Authors: Khait Yu. L. , Weil R. 
Published: July 2002

A kinetic many-body electron-related model of crystallization in a-Si:H(F) in the presence and absence of metal contacts is proposed. The model expresses the parameters of the formation of crystalline nuclei in terms of atomic and electronic material characteristics. The model is based on the kinetic electron-related theory of thermally activated rate processes in solids. The model considers picosecond atomic and electronic phenomena occurring in the nanometer vicinity of strongly fluctuating Si atoms executing diffusionlike jumps over energy barriers to more ‘‘ordered’’ positions which are associated with the formation of crystalline nuclei. The influence of random picosecond fluctuational heatings (coolings) in the nanometer vicinity of hopping atoms on the nucleation (crystallization) rate is considered. The following main results are obtained. (i) The Arrhenius-like equations for the nucleation time tN linking it with the Si self-diffusion in the metal/semiconductor interface are found from the kinetic consideration of the crystallization process, and are in agreement with experimental data. (ii) The Arrhenius activation energy ΔE and the pre-exponential factor t0N of the nucleation process are calculated.
They are expressed in terms of local parameters that characterize picosecond atomic and electronic processes which occur in the nanometer neighborhood of the hopping Si atoms. (iii) The ‘‘abnormally’’ large variations in the prefactor t0N (about 11 orders of magnitude) and the activation energy ΔE (a factor of 7.5) caused by metal contacts are explained. (iv) An explanation for a linear dependence between ln t0N and ΔE found experimentally in the crystallization in a-Si:H and a-Si:F is suggested. This dependence is known as the compensation effect (CEF). (v) Coefficients in the CEF equation and other kinetic parameters are calculated and expressed in terms of material characteristics, and are in good agreement with experimental data. (vi) An explanation for the large observed differences in the rate of nucleation in a-Si:H and a-Si:F is suggested. (vii) Causes for observed considerable differences in the effects of metals not forming and forming silicides on the crystallization are discussed. (viii) Si self-diffusion coefficients are calculated from the nucleation parameters in a-Si:H, a-Si:F, and in the metal/a-Si:H(F) interface for the following systems: a-Si:H/Al; a-Si:H/Pd; a-Si:F/Al; and a-Si:F/Pd.
Effect of translational energy on the molecular chemisorption of CO on Ni(111): Implications for the dynamics of the chemisorption process
Authors: Tang S. L. , Beckerle J. D. , Lee M. B. , Ceyer S. T. 
Published: July 2002

The effect of translational energy on the molecular chemisorption of CO on a Ni(111) surface is used as a probe of the dynamics of the adsorption process. Initial adsorption probabilities, apparent saturation coverages, spatially resolved Auger coverage profiles, and high resolution electron energy loss spectra of CO deposited on the Ni surface from a supersonic molecular beam are measured as a function of translational energy. It is found that the initial adsorption process for CO molecules incident with energies less than 4 kcal/mol differs from that for molecules incident with higher energies. Molecules with kinetic energies below 4 kcal/mol adsorb with an initial adsorption probability of 0.85±0.04 and a high apparent saturation coverage. Molecules with translational energies between 7 to 30 kcal/mol have an initial adsorption probability of 0.46±0.03, and an apparent saturation coverage approximately half that of the low energy molecules. Since the CO packing density and the final chemisorption states are shown to be independent of incident energy, the two apparent saturation coverages are the result of a difference in the surface area over which the CO molecules are spread. This is verified by spatially resolved Auger coverage profile measurements. Molecules at low energies are initially adsorbed with higher mobility than those incident with larger translational energies. High resolution electron energy loss spectra and thermal desorption spectra show no translational energy-induced dissociation. The frequency shift of the bridge-bonded CO stretching mode measured at the periphery of the molecular beam image shows that the energy-induced difference in the CO mobility during the chemisorption process is qualitatively similar on both the clean and partially CO-covered surface. These results are interpreted as evidence for two adsorption pathways into the molecular chemisorption state. Molecules incident on the surface with low energies are identified as mobile precursor molecules to the molecularly chemisorbed molecules. The precursor molecules have access to the molecular chemisorption state via a low energy pathway. As the incident translational energy is increased beyond the effective 4–7 kcal/mol energy barrier, a new adsorption pathway directly into the less
mobile chemisorption state becomes accessible. The natures of the precursor molecule, the effective energy barrier and the low energy pathway are discussed.
Dynamics of H2O2 photodissociation: OH product state and momentum distribution characterized by sub-Doppler and polarization spectroscopy
Authors: Gericke Karl-Heinz , Klee Stefan , Comes Franz Josef , Dixon Richard N. 
Published: July 2002

Hydrogen peroxide has been optically excited at a wavelength of 266 nm and the OH photofragment completely characterized by Doppler and polarization spectroscopy using the laser-induced fluorescence technique. The entire internal state distribution (vibration, rotation, spin, and Λ components), translational energy, angular distribution, rotational alignment, and vector correlations between rotational and translation motions of OH products is measured. The hydroxyl radicals are formed in the X 2Π3/2,1/2 ground state with 90% of the available energy (248 kJ/mol) being released as OH recoil translation. The angular distribution is nearly a sin2 θ distribution about the electric vector of the photolysis laser. The internal motion of OH is vibrationally cold (no vibrationally excited OH was found) while the rotational excitation in v″=0 can be described by a Boltzmann distribution with a temperature parameter of Trot=(1530±150) K. The two spin states are found to be populated nearly statistically, in contrast to the Λ components which show an increasing inversion with increasing OH rotation. The observed profiles of recoil Doppler broadened spectral lines are strongly dependent on the nature of the transition, the excitation–detection geometry, and the relative polarizations of the dissociating and analyzing laser light. However, the line intensities show only a minor dependence on geometry and polarization indicating a low alignment of OH photofragments (A(2)0≤0.1). For the first time the vector correlation between product rotational and translational motions was analyzed and evaluated in terms of the three bipolar moments β20(20), β00(22), and β20 (22). The bipolar moment β20(20) corresponds to the conventionally defined anisotropy parameter β=2β20(20) =−0.71. The angular distribution peaks in the direction perpendicular to the electric vector of the dissociating laser light, indicating the predominant electronic excited state in H2O2 being of 1A symmetry. The moment β00(22) increases
with JOH showing a bias towards vOH and JOH being parallel to one another. The moment β20(22) is a measure of the mutual correlation of the fragment translational and rotational vectors and the transition dipole vector μ in the parent molecule. The positive value of this moment [β20(22)=0.11] indicates that the expectation value of 〈J2y〉 should be very small when μ is parallel to the z axis and vOH perpendicular to μ (x axis). 〈J2x〉 originates in the torsional motion in the H2O2 parent molecule, while 〈J2z〉 reflects the bending vibration of nearly planar H2O2 where the H atoms are in the trans position.
Rotational line strengths for the photoionization of diatomic molecules
Authors: Xie Jinchun , Zare Richard N. 
Published: July 2002

We derive an expression for the probability that a diatomic molecule AB(n,v,N) in the electronic state n, vibrational state v, and rotational level N yields upon photoionization AB+(n+,v+,N+), where we assume Hund’s case (b) coupling. Our result is formally equivalent to the previous work of Buckingham, Orr, and Sichel [Phil. Trans. Roy. Soc. London, Ser. A 268, 147 (1970)] but differs substantially in that we use spherical tensor methods, which provide insight into the photoionization dynamics in terms of the contribution of different multipole moments. The total interaction term is given by the tensor product of the electric dipole moment operator T(1,μ0) and the multipole moment tensor T(l,m) describing the photoelectron in the lth partial wave. The interaction term is further simplified into a sum of reduced multipole moments T(k,p), where k=l±1 and p=μ0+m. For an isotropic distribution of initial states, the transition probability is given by P(N,N+)=1/3∑k Sk(N,N+)‖μ̄(k,q)‖2, where the factor of 1/3 arises from the use of a beam of polarized light, Sk(N,N+) is a generalized rotational line strength factor, and ‖μ̄(k,q)‖2=‖μl=k+1(k,q) ‖2+‖μl=k−1(k,q)‖2 is the sum of the squares of reduced multipole moment matrix elements.
The summation over k is restricted to even values for a (±)↔(±) transition and to odd values for a (±)↔(∓) transition. Thus, for an unpolarized molecular sample, the integrated photoelectron intensity associated with an N→N+ transition is the incoherent sum of the multipole moments that contribute to this transition, and each such contribution is an incoherent sum over l=k+1 and l=k−1. If the molecular sample is polarized (aligned and/or oriented), then the expression for the N→N+ integrated photoelectron intensity becomes a coherent sum over different k values with the same l value. Moreover, if the photoelectron distribution is angle resolved, then the expression for the N→N+ transition probability is a coherent sum over l values with the same k value when the molecular sample is unpolarized and cannot be separated into incoherent parts when the molecular sample is polarized. The expression for P(N,N+) has been used to fit the results of the photoionization of H2 and NO. In both cases, the fit obtained, which required only one or two adjustable parameters, respectively, agrees well with the experimental data. This treatment may be readily extended to photoionization of polyatomic molecules and to molecules that follow different angular momentum coupling cases.