Light emission from a scanning tunneling microscope: Fully retarded calculation

The light emission rate from a scanning tunneling microscope (STM) scanning a noble metal surface is calculated taking retardation effects into account. As in our previous, non-retarded theory [Johansson, Monreal, and Apell, Phys. Rev. B 42, 9210 (1990)], the STM tip is modeled by a sphere, and the dielectric properties of tip and sample are described by experimentally measured dielectric functions. The calculations are based on exact diffraction theory through the vector equivalent of the Kirchoff integral. The present results are qualitatively similar to those of the non-retarded calculations. The light emission spectra have pronounced resonance peaks due to the formation of a tip-induced plasmon mode localized to the cavity between the tip and the sample. At a quantitative level, the effects of retardation are rather small as long as the sample material is Au or Cu, and the tip consists of W or Ir. However, for Ag samples, in which the resistive losses are smaller, the inclusion of retardation effects in the calculation leads to larger changes: the resonance energy decreases by 0.2-0.3 eV, and the resonance broadens. These changes improve the agreement with experiment. For a Ag sample and an Ir tip, the quantum efficiency is $\approx$ 10$^{-4}$ emitted photons in the visible frequency range per tunneling electron. A study of the energy dissipation into the tip and sample shows that in total about 1 % of the electrons undergo inelastic processes while tunneling.Comment: 16 pages, 10 figures (1 ps, 9 tex, automatically included); To appear in Phys. Rev. B (15 October 1998

Assessment of ePrescription quality: an observational study at three mail-order pharmacies

<p>Abstract</p> <p>Background</p> <p>The introduction of electronic transfer of prescriptions (ETP) or ePrescriptions in ambulatory health care has been suggested to have a positive impact on the prescribing and dispensing processes. Thereby, implying that ePrescribing can improve safety, quality, efficiency, and cost-effectiveness. In December 2007, 68% of all new prescriptions were transferred electronically in Sweden. The aim of the present study was to assess the quality of ePrescriptions by comparing the proportions of ePrescriptions and non-electronic prescriptions necessitating a clarification contact (correction, completion or change) with the prescriber at the time of dispensing.</p> <p>Methods</p> <p>A direct observational study was performed at three Swedish mail-order pharmacies which were known to dispense a large proportion of ePrescriptions (38–75%). Data were gathered on all ePrescriptions dispensed at these pharmacies over a three week period in February 2006. All clarification contacts with prescribers were included in the study and were classified and assessed in comparison with all drug prescriptions dispensed at the same pharmacies over the specified period.</p> <p>Results</p> <p>Of the 31225 prescriptions dispensed during the study period, clarification contacts were made for 2.0% (147/7532) of new ePrescriptions and 1.2% (79/6833) of new non-electronic prescriptions. This represented a relative risk (RR) of 1.7 (95% CI 1.3–2.2) for new ePrescriptions compared to new non-electronic prescriptions. The increased RR was mainly due to 'Dosage and directions for use', which had an RR of 7.6 (95% CI 2.8–20.4) when compared to other clarification contacts. In all, 89.5% of the suggested pharmacist interventions were accepted by the prescriber, 77.7% (192/247) as suggested and an additional 11.7% (29/247) after a modification during contact with the prescriber.</p> <p>Conclusion</p> <p>The increased proportion of prescriptions necessitating a clarification contact for new ePrescriptions compared to new non-electronic prescriptions indicates the need for an increased focus on quality aspects in ePrescribing deployment. ETP technology should be developed towards a two-way communication between the prescriber and the pharmacist with automated checks of missing, inaccurate, or ambiguous information. This would enhance safety and quality for the patient and also improve efficiency and cost-effectiveness within the health care system.</p

Tissue architecture delineates field cancerization in BRAFV600E-induced tumor development

Cancer cells hijack developmental growth mechanisms but whether tissue morphogenesis and architecture modify tumorigenesis is unknown. Here, we characterized a new mouse model of sporadic thyroid carcinogenesis based on inducible expression of BRAF carrying a Val600 Glu (V600E) point mutation (BRAFV600E) from the thyroglobulin promoter (TgCreERT2). Spontaneous activation of this Braf-mutant allele due to leaky activity of the Cre recombinase revealed that intrinsic properties of thyroid follicles determined BRAF-mutant cell fate. Papillary thyroid carcinomas developed multicentrically within a normal microenvironment. Each tumor originated from a single follicle that provided a confined space for growth of a distinct tumor phenotype. Lineage tracing revealed oligoclonal tumor development in infancy and early selection of BRAFV600E kinase inhibitor-resistant clones. Somatic mutations were few, non-recurrent and limited to advanced tumors. Female mice developed larger tumors than males, reproducing the gender difference of human thyroid cancer. These data indicate that BRAFV600E-induced tumorigenesis is spatiotemporally regulated depending on the maturity and heterogeneity of follicles. Moreover, thyroid tissue organization seems to determine whether a BRAF- mutant lineage becomes a cancerized lineage. The TgCreERT2; BrafCA/+ sporadic thyroid cancer mouse model provides a new tool to evaluate drug therapy at different stages of tumor evolution

Mouse DRG Cell Line with Properties of Nociceptors

In vitro cell lines from DRG neurons aid drug discovery because they can be used for early stage, high-throughput screens for drugs targeting pain pathways, with minimal dependence on animals. We have established a conditionally immortal DRG cell line from the Immortomouse. Using immunocytochemistry, RT-PCR and calcium microfluorimetry, we demonstrate that the cell line MED17.11 expresses markers of cells committed to the sensory neuron lineage. Within a few hours under differentiating conditions, MED17.11 cells extend processes and following seven days of differentiation, express markers of more mature DRG neurons, such as NaV1.7 and Piezo2. However, at least at this time-point, the nociceptive marker NaV1.8 is not expressed, but the cells respond to compounds known to excite nociceptors, including the TRPV1 agonist capsaicin, the purinergic receptor agonist ATP and the voltage gated sodium channel agonist, veratridine. Robust calcium transients are observed in the presence of the inflammatory mediators bradykinin, histamine and norepinephrine. MED17.11 cells have the potential to replace or reduce the use of primary DRG culture in sensory, pain and developmental research by providing a simple model to study acute nociception, neurite outgrowth and the developmental specification of DRG neurons

Visceral leishmaniasis caused by Leishmania infantum in a Spanish patient in Argentina: What is the origin of the infection? Case report

BACKGROUND: The question "Where have you been?" is a common one asked by doctors in Northern Europe and America when faced with clinical symptoms not typical of their country. This question must also arise in the clinics of developing countries in which non-autochthonous cases such as the one described here can appear. Important outbreaks of Leishmania infantum have been recorded in the last decade in several Latin American countries but its presence has not yet been recorded in Argentina. We report the first case of visceral leishmaniasis owing to L. infantum in this country. CASE PRESENTATION: A 71-year-old Spanish woman who has been living in Mendoza, Argentina, during the last 40 years presented with a history of high fever and shivering, anemia, leukopenia and splenomegaly over two years. Argentinian doctors did not suspect visceral leishmaniasis even when the histological analysis revealed the presence of "intracytoplasmatic spheroid particles compatible with fungal or parasitic infection". After a serious deterioration in her health, she was taken to Spain where she was evaluated and visceral leishmaniasis was established. Specific identification of the parasite was done by PCR-ELISA, isoenzyme electrophoresis and RAPD-PCR. CONCLUSION: We would like to point out that: i) cases such as the one described here, which appear in non-endemic areas, can pass unnoticed by the clinical physician. ii) in countries in which these introduced cases reside, in-depth parasitological studies are required into vectors and possible reservoirs to rule out the rare case of local infection and, once infection has taken place, to ensure that this does not spread by anthroponotic transmission or a competent reservoir