Wafer-scale epitaxial modulation of quantum dot density.

Precise control of the properties of semiconductor quantum dots (QDs) is vital for creating novel devices for quantum photonics and advanced opto-electronics. Suitable low QD-densities for single QD devices and experiments are challenging to control during epitaxy and are typically found only in limited regions of the wafer. Here, we demonstrate how conventional molecular beam epitaxy (MBE) can be used to modulate the density of optically active QDs in one- and two- dimensional patterns, while still retaining excellent quality. We find that material thickness gradients during layer-by-layer growth result in surface roughness modulations across the whole wafer. Growth on such templates strongly influences the QD nucleation probability. We obtain density modulations between 1 and 10 QDs/µm2 and periods ranging from several millimeters down to at least a few hundred microns. This method is universal and expected to be applicable to a wide variety of different semiconductor material systems. We apply the method to enable growth of ultra-low noise QDs across an entire 3-inch semiconductor wafer.

A novel VWF variant associated with type 2 von Willebrand disease in German Wirehaired Pointers and German Shorthaired Pointers.

Von Willebrand disease (VWD), caused by deficiency of the von Willebrand factor (VWF), is the most common bleeding disorder in humans and dogs. The complete cDNA encoding VWF of a German Wirehaired Pointer with type 2 VWD was sequenced, and we found four variants that alter the amino acid sequence. These variants were: c.1657T>G corresponding to p.Trp553Gly; c.1777G>A (p.Glu593Lys); c.4937A>G (p.Asn1646Ser) and c.5544G>A (p.Met1848Ile). A haplotype of the c.1657G, c.1777A and c.4937G alleles co-segregated with the VWF antigen level in a four-generation pedigree with the disease. Healthy dogs of the breed were found that were homozygous for the c.1777A or the c.5544A allele, indicating that these variants do not cause VWD. Dogs that were homozygous for the c.4937G allele and had no signs of a bleeding disorder were observed in the Chinese Crested dog breed. Thus, only the c.1657G variant was found in the homozygous state exclusively in VWD affecteds, and this variant is the strongest candidate to be the cause of VWD type 2 in the German Wirehaired Pointer breed. A screen of German Shorthaired Pointers indicated that the variant also segregates with VWD in this breed.

Suppression of the human spinal H-reflex by propofol: a quantitative analysis.

BACKGROUND: The spinal cord is an important site of anaesthetic action because it mediates surgical immobility. During anaesthesia with volatile anaesthetics, it has been shown that the suppression of the spinal H-reflex correlates with surgical immobility. To evaluate whether the H-reflex could also be a possible candidate for monitoring immobility during propofol anaesthesia, this study assessed the concentration-dependent suppression of the H-reflex by propofol. To discriminate different effect sites, the individual concentration response-curves and the t(1/2ke0) of the H-reflex have been compared with those of two EEG parameters. METHODS: In 18 patients, anaesthesia was induced and maintained with propofol infused using a target-controlled infusion pump at stepwise increasing and decreasing plasma concentrations between 0.5 and 4.5 mg/l. The H-reflex of the soleus muscle was recorded at a frequency of 0.1 Hz. Calculated propofol concentrations and H-reflex amplitude were analysed in terms of a pharmacokinetic-pharmacodynamic (PKPD) model with a sigmoid concentration-response function. RESULTS: For slowly increasing propofol concentrations, computer fits of the PKPD model for H-reflex suppression by propofol yielded the following median parameters: EC50 1.1 (0.8-1.7) mg/l, slope parameter 2.4 (2.0-3.7), and a t(1/2ke0) of 6.7 (2.8-7.5, 25-75% quantiles) min. For the bispectral index, the t(1/2ke0) was 2.2 (1.8-3.1) min and for the spectral edge frequency at the 95th percentile of the power spectrum 2.8 (1.9-3.2) min. CONCLUSIONS: Propofol, unlike sevoflurane, suppresses the spinal H-reflex at concentrations far lower than the C50 skin incision. The differences in t(1/2ke0)-values indicate the presence of different effect compartments for effects on the H-reflex and the EEG.

Comparative studies with Kollicoat MAE 30 D and Kollicoat MAE 30 DP in aqueous spray dispersions and enteric coatings on highly swellable caffeine cores.

A film formulation containing Kollicoat MAE 30 D, Kollidon 30, Sicovit Rot 30, titanium dioxide, talc, and a plasticizer for the aqueous manufacture of enteric coatings was studied for the coagulations occurring with certain plasticizers and for differences in resistance on highly swellable caffeine cores. Also included in these investigations were the latices Kollicoat MAE 30 DP and Eudragit L 30 D-55. The coagulations occurring with all three film latices can be attributed to the presence of Kollidon 30 together with certain excipients. Preparations with Kollidon 30, but without color pigments, showed no tendency to coagulate. The advantage of propylene glycol (PG) compared to other plasticizers such as triethyl citrate (TEC) is that no coagulations occurred, even in the presence of Kollidon 30 and color pigments. Among the Kollidon 30-free film formulations examined, a plasticizer content of 10-15% PG or TEC gave the best results. Optimal pigment distribution in the coat originally produced by Kollidon 30 can optionally be achieved by prolonged stirring of the pigment suspension. The resistance can be further improved by inclusion of a subcoating with Kollidon VA 64. Kollicoat MAE 30 D and MAE 30 DP and Eudragit L 30 D-55 showed identical behavior in this study.

Trends in pharmacotherapy of Schizoaffective and bipolar affective disorders: a 5-year naturalistic study.

OBJECTIVE: The authors' goal was to determine if the actual treatment of schizoaffective and bipolar affective disorders had changed in light of recent clinical drug trials that have suggested that valproate and carbamazepine may be equivalent in efficacy to lithium. METHOD: Medication utilization rates for each 6-month period from July 1, 1989, to June 30, 1994, were compiled from the clinical database of the Palo Alto Veterans Affairs Medical Center. RESULTS: The use of valproate and valproate plus lithium was negligible in 1989. by 1994, these medication regimens accounted for 25% of the standard antimanic treatments used for bipolar affective disorder and 38% of the treatments used for schizoaffective disorder. Regimens of carbamazepine and carbamazepine plus lithium dropped from 24% of antimanic treatments in 1989 to 18% in 1994. From 1989 to 1994, there was a decline in the rate of lithium monotherapy for treatment of bipolar affective disorder (from 84% to 43%) and schizoaffective disorder (from 100% to 53%). CONCLUSIONS: In the past 5 years, valproate monotherapy has increased as a percentage of total antimanic pharmacotherapies, while lithium monotherapy has declined.