CiteULike: Author Ackerson

Coherent crystallography of shear-aligned crystals of hard-sphere colloids

J Liu — 2008-08-17T20:18:41-00:00

Physical Review E, Vol. 48, No. 2. (1993), 1106.

Classical growth of hard-sphere colloidal crystals

Bruce Ackerson — 2008-07-23T19:35:20-00:00

Physical Review E, Vol. 52, No. 6. (1 December 1995), pp. 6448-6460.

The classical theory of nucleation and growth of crystals is examined for concentrated suspensions of hard-sphere colloidal particles. The work of Russel is modified, extended, and evaluated, explicitly. Specifically, the Wilson-Frenkel growth law is modified to include the Gibbs-Thomson effect and is evaluated numerically. The results demonstrate that there is a critical nucleus radius below which crystal nuclei will not grow. A kinetic coefficient determines the maximum growth velocity possible. For large values of this coefficient, quenches to densities above the melting density show interface limited growth with the crystal radius increasing linearly with time. For quenches into the coexistence region the growth is diffusion limited, with the crystal radius increasing as the square root of elapsed time. Smaller values of the kinetic coefficient produce long lived transients which evidence quasi-power-law growth behavior with exponents between one half and unity. The smaller kinetic coefficients also lead to larger crystal compression. Crystal compression and nonclassical exponents have been observed in recent experiments. The theory is compared to data from small angle scattering studies of nucleation and growth in suspensions of hard colloidal spheres. The experimental nucleation rate is much larger than the theoretically predicted value as the freezing point is approached but shows better agreement near the melting point. The crystal growth with time is described reasonably well by the theory and suggests that the experiments are observing long lived transient rather than asymptotic growth behavior.

Shear-Induced Order in Suspensions of Hard Spheres

Bruce Ackerson — 2008-04-25T23:56:06-00:00

Physical Review Letters, Vol. 61, No. 8. (1988), 1033.

Choices physicians would make if they were the parents of a child with hypoplastic left heart syndrome.

AA Kon — 2008-03-27T15:23:57-00:00

Am J Cardiol, Vol. 91, No. 12. (15 June 2003)

A cell-penetrating ARF peptide inhibitor of FoxM1 in mouse hepatocellular carcinoma treatment.

GA Gusarova — 2008-01-25T02:02:18-00:00

J Clin Invest, Vol. 117, No. 1. (January 2007), pp. 99-111.

The forkhead box m1 (Foxm1) transcription factor is essential for initiation of carcinogen-induced liver tumors; however, whether FoxM1 constitutes a therapeutic target for liver cancer treatment remains unknown. In this study, we used diethylnitrosamine/phenobarbital treatment to induce hepatocellular carcinomas (HCCs) in either WT mice or Arf(-/-)Rosa26-FoxM1b Tg mice, in which forkhead box M1b (FoxM1b) is overexpressed and alternative reading frame (ARF) inhibition of FoxM1 transcriptional activity is eliminated. To pharmacologically reduce FoxM1 activity in HCCs, we subjected these HCC-bearing mice to daily injections of a cell-penetrating ARF(26-44) peptide inhibitor of FoxM1 function. After 4 weeks of this treatment, HCC regions displayed reduced tumor cell proliferation and angiogenesis and a significant increase in apoptosis within the HCC region but not in the adjacent normal liver tissue. ARF peptide treatment also induced apoptosis of several distinct human hepatoma cell lines, which correlated with reduced protein levels of the mitotic regulatory genes encoding polo-like kinase 1, aurora B kinase, and survivin, all of which are transcriptional targets of FoxM1 that are highly expressed in cancer cells and function to prevent apoptosis. These studies indicate that ARF peptide treatment is an effective therapeutic approach to limit proliferation and induce apoptosis of liver cancer cells in vivo.

Serial correlation in unequally spaced longitudinal data

Richard Jones — 2008-01-18T18:47:19-00:00

Biometrika, Vol. 77, No. 4. (1 December 1990), pp. 721-731.

Serial correlation in the within subject error structure in longitudinal data with unequally spaced observations is modelled using continuous time autoregressive moving averages. The models considered have both fixed and random effects in addition to serially correlated within subject errors. Two approaches are presented for calculating the exact likelihood for a model when the errors are Gaussian. The first calculates the covariance matrices for each subject for assumed values of the unknown parameters and estimates the fixed parameters by weighted least squares. The second uses a state space model and the Kalman filter to calculate the exact likelihood. Both methods involve the use of complex arithmetic. Nonlinear optimization is used to obtain maximum likelihood estimates of the parameters. 10.1093/biomet/77.4.721

Increased dopamine release in the human amygdala during performance of cognitive tasks.

I Fried — 2007-11-19T19:43:15-00:00

Nat Neurosci, Vol. 4, No. 2. (February 2001), pp. 201-206.

Accumulating data support a critical involvement of dopamine in the modulation of neuronal activity related to cognitive processing. The amygdala is a major target of midbrain dopaminergic neurons and is implicated in learning and memory processes, particularly those involving associations between novel stimuli and reward. We used intracerebral microdialysis to directly sample extracellular dopamine in the human amygdala during the performance of cognitive tasks. The initial transition from rest to either a working memory or a reading task was accompanied by significant increases in extracellular dopamine concentration of similar magnitude. During a sustained word paired-associates learning protocol, increase in dopamine release in the amygdala related to learning performance. These data provide evidence for sustained activation of the human mesolimbic dopaminergic system during performance of cognitive tasks.

Structure of a Thiol Monolayer-Protected Gold Nanoparticle at 1.1 A Resolution

Pablo Jadzinsky — 2007-10-23T21:26:25-00:00

Science, Vol. 318, No. 5849. (19 October 2007), pp. 430-433.

Structural information on nanometer-sized gold particles has been limited, due in part to the problem of preparing homogeneous material. Here we report the crystallization and x-ray structure determination of a p-mercaptobenzoic acid (p-MBA)protected gold nanoparticle, which comprises 102 gold atoms and 44 p-MBAs. The central gold atoms are packed in a Marks decahedron, surrounded by additional layers of gold atoms in unanticipated geometries. The p-MBAs interact not only with the gold but also with one another, forming a rigid surface layer. The particles are chiral, with the two enantiomers alternating in the crystal lattice. The discrete nature of the particle may be explained by the closing of a 58-electron shell. 10.1126/science.1148624

Hard-sphere dispersions: Small-wave-vector structure-factor measurements in a linear shear flow

Bruce Ackerson — 2007-10-08T09:27:23-00:00

Physical Review A, Vol. 37, No. 12. (15 June 1988), 4819.

Small-scattering-wave-vector structure-factor measurements have been made for model hard-sphere suspensions undergoing a steady linear shear flow. The samples are comprised of sterically stabilized silica particles in cyclohexane and have been well characterized previously by rheological; light scattering; and neutron scattering measurements. These combined measurements provide a strict test of recent theories of microscopic order in suspensions undergoing shear and suggest a picture which unifies several intuitive notions about suspensions undergoing shear flow: distortion of the pair correlation function; clustering; layering; and nonequilibrium phase transitions.

Hemoglobin level, chronic kidney disease, and the risks of death and hospitalization in adults with chronic heart failure: the Anemia in Chronic Heart Failure: Outcomes and Resource Utilization (ANCHOR) Study.

AS Go — 2007-08-11T15:44:36-00:00

Circulation, Vol. 113, No. 23. (13 June 2006), pp. 2713-2723.

BACKGROUND: Previous studies have associated reduced hemoglobin levels with increased adverse events in heart failure. It is unclear, however, whether this relation is explained by underlying kidney disease, treatment differences, or associated comorbidity. METHODS AND RESULTS: We examined the associations between hemoglobin level, kidney function, and risks of death and hospitalization in persons with chronic heart failure between 1996 and 2002 within a large, integrated, healthcare delivery system in northern California. Longitudinal outpatient hemoglobin and creatinine levels and clinical and treatment characteristics were obtained from health plan records. Glomerular filtration rate (GFR; mL.min(-1).1.73 m(-2)) was estimated from the Modification of Diet in Renal Disease equation. Mortality data were obtained from state death files; heart failure admissions were identified by primary discharge diagnoses. Among 59,772 adults with heart failure, the mean age was 72 years and 46% were women. Compared with that for hemoglobin levels of 13.0 to 13.9 g/dL, the multivariable-adjusted risk of death increased with lower hemoglobin levels: an adjusted hazard ratio (HR) of 1.16 and 95% confidence interval (CI) of 1.11 to 1.21 for hemoglobin levels of 12.0 to 12.9 g/dL; HR, 1.50 and 95% CI, 1.44 to 1.57 for 11.0 to 11.9 g/dL; HR, 1.89 and 95% CI, 1.80 to 1.98 for 10.0 to 10.9; HR, 2.31 and 95% CI, 2.18 to 2.45 for 9.0 to 9.9; and HR, 3.48 and 95% CI, 3.25 to 3.73 for <9.0 g/dL. Hemoglobin levels > or = 17.0 g/dL were associated with an increased risk of death (adjusted HR, 1.42; 95% CI, 1.24 to 1.63). Compared with those with a GFR > or = 60 mL . min(-1).1.73 m(-2), persons with a GFR <45 mL.min(-1).1.73 m(-2) had an increased mortality risk: adjusted HR, 1.39 and 95% CI, 1.34 to 1.44 for 30 to 44; HR, 2.28 and 95% CI, 2.19 to 2.39 for 15 to 29; HR, 3.26 and 95% CI, 3.05 to 3.49 for <15; and HR, 2.44 and 95% CI, 2.28 to 2.61 for those on dialysis. Relations were similar for the risk of hospitalization. The findings did not differ among patients with preserved or reduced systolic function, and hemoglobin level was an independent predictor of outcomes at all levels of kidney function. CONCLUSIONS: Very high (> or = 17 g/dL) or reduced (<13 g/dL) hemoglobin levels and chronic kidney disease independently predict substantially increased risks of death and hospitalization in heart failure, regardless of the level of systolic function. Randomized trials are needed to evaluate whether raising hemoglobin levels can improve outcomes in chronic heart failure.

Overexpression of the Drosophila vesicular monoamine transporter increases motor activity and courtship but decreases the behavioral response to cocaine

HY Chang — 2005-09-27T18:08:00-00:00

Molecular Psychiatry, Vol. aop, No. current.

The effect of patient and provider reminders on mammography and Papanicolaou smear screening in a large health maintenance organization.

CP Somkin — 2005-10-12T18:47:04-00:00

Arch Intern Med, Vol. 157, No. 15. (5 1997), pp. 1658-1664.

BACKGROUND: We evaluated the effectiveness of 2 reminder interventions to increase the use of screening mammograms and Papanicolaou (Pap) smears among female members of a large health maintenance organization. METHODS: Seven thousand seventy-seven female health maintenance organization members (aged 50-74 years with no prior mammogram in the previous 30 months or aged 20-64 years with no prior Pap smear in the previous 36 months) were randomized to receive one of the following: a letter inviting them to make an appointment for a mammogram or a Pap smear; in addition to the letter, a reminder manually placed in the patient's medical chart alerting providers of that member's need for screening; or their usual care. RESULTS: Compared with women who did not receive the reminder letter, women who did receive the letter were more likely to obtain mammograms (16.0% vs 25.5%, respectively; P < .001) or Pap smears (9.1% vs 19.5%, respectively; P < .001) in the 6 months following their entry into the study. Compared with women who received only the reminder letter, women who received a reminder letter and had a reminder placed in their medical chart were more likely to obtain mammograms (26.5% vs 30.9%, respectively; P = .02) and marginally more likely to receive Pap smears (19.5% vs 22.8%, respectively; P = .04). CONCLUSIONS: We recommend the use of patient reminder letters as a first step in a mammography or Pap smear screening outreach program. Further research is needed to evaluate a cost-effective provider reminder system and additional outreach strategies directed to women who do not use health care services.