Prevention of chemotherapy-induced nausea and vomiting in the real-world setting in Spain.

PURPOSE: Proper monitoring and management of chemotherapy-induced nausea and vomiting (CINV) with antiemetics is crucial for cancer patients. This study aimed to evaluate the use of antiemetics for the treatment of highly emetogenic chemotherapy (HEC) including carboplatin in the real-world setting in Spain. METHODS: A representative panel of cancer specialists was asked to collect information about the antiemetic treatments provided to patients receiving chemotherapy. Records formed part of the Global Oncology Monitor© database (Ipsos Healthcare, London, UK). Chemotherapy data were extrapolated using Ipsos Healthcare's projection methodology. RESULTS: A total of 73 experts were finally included. Data from 9519 patients, estimated to be representative of 202,084 patients, were collected. HEC (and carboplatin-based chemotherapy) was administered to 73,118 (36%) patients, cisplatin-based therapy being the most frequent treatment (n = 34,649, 47.38%). Neurokinin-1 receptor antagonists (NK1RAs) alone or in combination were used as prophylaxis for CINV in 14,762 (20%) patients, while the combination of NK1RA with 5-hydroxytryptamine-3 receptor antagonist (5-HT3RAs) and dexamethasone as recommended by the international guidelines was used in 5849 (8%) patients only. No antiemetic prophylaxis was administered to 8.46% of the patients receiving HEC (n = 6189). Physicians classified cisplatin-, anthracycline-cyclophosphamide (AC-), and carboplatin-based regimens as HEC in 63%, 22% and 4% of the cases, respectively. CONCLUSIONS: The use of NK1RA-containing regimens for CINV prevention in patients treated with HEC was less than expected, suggesting poor adherence to international antiemetic guidelines.

Bonding at the SiC-SiO2 interface and the effects of nitrogen and hydrogen.

Unlike the Si-SiO2 interface, the SiC-SiO2 interface has large defect densities. Though nitridation has been shown to reduce the defect density, the effect of H remains an open issue. Here we combine experimental data and the results of first-principles calculations to demonstrate that a Si-C-O bonded interlayer with correlated threefold-coordinated C atoms accounts for the observed defect states, for passivation by N and atomic H, and for the nature of residual defects.

Design rules to achieve high-T(C) ferromagnetism in (Ga, Mn)As alloys.

The Curie temperature T(C) of ferromagnetic semiconductor alloys depends not only on the alloy composition, but also on the spatial configuration of the magnetic impurities. Here we use a set of first-principle-calculated Curie temperatures to uncover-via a statistical, 'data mining' approach-the rules that govern the dependence of T(C) on the configuration of Mn substitutional impurities in GaAs. We find that T(C) is lowered (raised) when the average number of first (third and fourth) nearest-neighbour Mn pairs increases, suggesting simple atom-by-atom strategies to achieve high T(C) in (Ga, Mn)As alloys.

The peculiar electronic structure of PbSe quantum dots.

PbSe is a pseudo-II-VI material distinguished from ordinary II-VI's (e.g., CdSe, ZnSe) by having both its valence band maximum (VBM) and its conduction band minimum (CBM) located at the fourfold-degenerate L-point in the Brillouin zone. It turns out that this feature dramatically affects the properties of the nanosystem. We have calculated the electronic and optical properties of PbSe quantum dots using an atomistic pseudopotential method, finding that the electronic structure is different from that of ordinary II-VI's and, at the same time, is more subtle than what k.p or tight-binding calculations have suggested previously for PbSe. We find the following in PbSe dots: (i) The intraband (valence-to-valence and conduction-to-conduction) as well as interband (valence-to-conduction) excitations involve the massively split L-manifold states. (ii) In contrast to previous suggestions that the spacings between valence band levels will equal those between conduction band levels (because the corresponding effective-masses me approximately mh are similar), we find a densely spaced hole manifold and much sparser electron manifold. This finding reflects the existence of a few valence band maxima in bulk PbSe within approximately 500 meV. This result reverses previous expectations of slow hole cooling in PbSe dots. (iii) The calculated optical absorption spectrum reproduces the measured absorption peak that had previously been attributed to the forbidden 1Sh --> 1Pe or 1Ph --> 1Se transitions on the basis of k.p calculations. However, we find that this transition corresponds to an allowed 1Ph --> 1Pe excitation arising mainly from bulk states near the L valleys on the Gamma-L lines of the Brillouin zone. We discuss this reinterpretation of numerous experimental results.

Impact ionization can explain carrier multiplication in PbSe quantum dots.

The efficiency of conventional solar cells is limited because the excess energy of absorbed photons converts to heat instead of producing electron-hole pairs. Recently, efficient carrier multiplication has been observed in semiconductor quantum dots. In this process, a single, high-energy photon generates multiple electron-hole pairs. Rather exotic mechanisms have been proposed to explain the efficiency of carrier multiplication in PbSe quantum dots. Using atomistic pseudopotential calculations, we show here that the more conventional impact ionization mechanism, whereby a photogenerated electron-hole pair decays into a biexciton in a process driven by Coulomb interactions between the carriers, can explain both the rate (<<1 ps) and the energy threshold ( approximately 2.2 times the band gap) of carrier multiplication, without the need to invoke alternative mechanisms.

First-principles combinatorial design of transition temperatures in multicomponent systems: the case of Mn in GaAs.

The transition temperature TC of multicomponent systems--ferromagnetic, superconducting, or ferroelectric--depends strongly on the atomic arrangement, but an exhaustive search of all configurations for those that optimize TC is difficult, due to the astronomically large number of possibilities. Here we address this problem by parametrizing the TC of a set of approximately 50 input configurations, calculated from first principles, in terms of configuration variables ("cluster expansion"). Once established, this expansion allows us to search almost effortlessly the transition temperature of arbitrary configurations. We apply this approach to search for the configuration of Mn dopants in GaAs having the highest ferromagnetic Curie temperature. Our general approach of cluster expanding physical properties opens the way to design based on exploring a large space of configurations.

Enhanced current transport at grain boundaries in high-T(c) superconductors.

Large-scale applications of high-transition-temperature (high-T(c)) superconductors, such as their use in superconducting cables, are impeded by the fact that polycrystalline materials (the only practical option) support significantly lower current densities than single crystals. The superconducting critical current density (J(c)) across a grain boundary drops exponentially if the misorientation angle exceeds 2 degrees -7 degrees. Grain texturing reduces the average misorientation angle, but problems persist. Adding impurities (such as Ca in YBa2Cu3O7-delta; YBCO) leads to increased J(c) (refs 9, 10), which is generally attributed to excess holes introduced by Ca2+ substituting for Y3+ (ref. 11). However, a comprehensive physical model for the role of grain boundaries and Ca doping has remained elusive. Here we report calculations, imaging and spectroscopy at the atomic scale that demonstrate that in poly-crystalline YBCO, highly strained grain-boundary regions contain excess O vacancies, which reduce the local hole concentration. The Ca impurities indeed substitute for Y, but in grain-boundary regions under compression and tension they also replace Ba and Cu, relieving strain and suppressing O-vacancy formation. Our results demonstrate that the ionic radii are more important than their electronic valences for enhancing J(c).

A. Franceschetti--great ophthalmologist and humanitarian.

A. Franceschetti is well known for his work in ocular genetics; however, his role in creating a department that served as a haven for ophthalmologists during World War II is less well known. Franceschetti was an enthusiastic and multitalented researcher whose contributions to ophthalmology are far-reaching.

[Strabismus, hemianopsia and the sundial of Mawas and Franceschetti]. / Le cadran solaire de Mawas et Franceschetti.

UNLABELLED: THE ARTIFACT: The artifact is a light rectangular slate of black cardboard showing two white lines at 40 degrees angle. It provokes physiological diplopia in lateral vision. BACKGROUND: In normal subjects, the right oblique line stimulates the right nasal hemiretina, perceived as an oblique line, and the left temporal hemiretina, perceived as a vertical line, both lines being on the right hand side. Likewise, the left oblique line is seen as two lines on the left hand side. The 4 lines form and M and a W combined. The strabismus subject sees 3 lines for he neutralizes one; the alternating squint sees only 2; the heterophoric sees 4 lines, two of which blurred, and the hemianopic sees only part of the dial. RESULTS: The subject must select the image he sees from an array of possibilities shown on the back of the dial. From 5 years of age on, normal subjects select the [symbol: see text] or the "butterfly"; hemianopic subjects correctly describe the loss of either the left or right field. CONCLUSIONS: The sundial facilitates both the screening and the treatment of binocular vision disorders. Bangerter's hemifilter will be used in association with exercises for physiological diplopia at home under monthly orthoptic control. All this made it possible to obtain useful peripheral fusion in early onset strabismus.

[The Lang stereo-test in mass screening of kindergarten students]. / Der Lang-Stereotest in Reihenuntersuchungen in Kindergärten.

During the 1990-91 school year 2856 kindergarten children underwent screening in the Geneva area. Their visual acuity was measured and stereoscopic vision estimated with the Lang test. Positive cases were referred to an ophthalmologist for diagnosis.