A candidate super-Earth planet orbiting near the snow line of Barnard's star.

Barnard's star is a red dwarf, and has the largest proper motion (apparent motion across the sky) of all known stars. At a distance of 1.8 parsecs1, it is the closest single star to the Sun; only the three stars in the α Centauri system are closer. Barnard's star is also among the least magnetically active red dwarfs known2,3 and has an estimated age older than the Solar System. Its properties make it a prime target for planetary searches; various techniques with different sensitivity limits have been used previously, including radial-velocity imaging4-6, astrometry7,8 and direct imaging9, but all ultimately led to negative or null results. Here we combine numerous measurements from high-precision radial-velocity instruments, revealing the presence of a low-amplitude periodic signal with a period of 233 days. Independent photometric and spectroscopic monitoring, as well as an analysis of instrumental systematic effects, suggest that this signal is best explained as arising from a planetary companion. The candidate planet around Barnard's star is a cold super-Earth, with a minimum mass of 3.2 times that of Earth, orbiting near its snow line (the minimum distance from the star at which volatile compounds could condense). The combination of all radial-velocity datasets spanning 20 years of measurements additionally reveals a long-term modulation that could arise from a stellar magnetic-activity cycle or from a more distant planetary object. Because of its proximity to the Sun, the candidate planet has a maximum angular separation of 220 milliarcseconds from Barnard's star, making it an excellent target for direct imaging and astrometric observations in the future.

Novel PORCN mutations in focal dermal hypoplasia.

Focal dermal hypoplasia (FDH), Goltz or Goltz-Gorlin syndrome, is an X-linked dominant multisystem disorder characterized primarily by involvement of the skin, skeletal system and eyes. We screened for mutations in the PORCN gene in eight patients of Belgian and Finnish origin with firm clinical suspicion of FDH. First, we performed quantitative PCR (qPCR) analysis to define the copy number at this locus. Next, we sequenced the coding regions and flanking intronic sequences of the PORCN gene. Three de novo mutations were identified in our patients with FDH: a 150-kb deletion removing six genes including PORCN, as defined by qPCR and X-array-CGH, and two heterozygous missense mutations; c.992T>G (p.L331R) in exon 11 and c.1094G>A (p.R365Q) in exon 13 of the gene. Both point mutations changed highly conserved amino acids and were not found in 300 control X chromosomes. The three patients in whom mutations were identified all present with characteristic dermal findings together with limb manifestations, which were not seen in our mutation-negative patients. The clinical characteristics of our patients with PORCN mutations were compared with the previously reported mutation-positive cases. In this report, we summarize the literature on PORCN mutations and associated phenotypes.

Direct measurement of electrical conductance through a self-assembled molecular layer.

The self-assembly of organic molecules on surfaces is a promising approach for the development of nanoelectronic devices. Although a variety of strategies have been used to establish stable links between molecules, little is known about the electrical conductance of these links. Extended electronic states, a prerequisite for good conductance, have been observed for molecules adsorbed on metal surfaces. However, direct conductance measurements through a single layer of molecules are only possible if the molecules are adsorbed on a poorly conducting substrate. Here we use a nanoscale four-point probe to measure the conductivity of a self-assembled layer of cobalt phthalocyanine on a silver-terminated silicon surface as a function of thickness. For low thicknesses, the cobalt phthalocyanine molecules lie flat on the substrate, and their main effect is to reduce the conductivity of the substrate. At higher thicknesses, the cobalt phthalocyanine molecules stand up to form stacks and begin to conduct. These results connect the electronic structure and orientation of molecular monolayer and few-layer systems to their transport properties, and should aid in the rational design of future devices.

Anomalous bismuth-stabilized (2x1) reconstructions on GaAs(100) and InP(100) surfaces.

First-principles phase diagrams of bismuth-stabilized GaAs- and InP(100) surfaces demonstrate for the first time the presence of anomalous (2x1) reconstructions, which disobey the common electron counting principle. Combining these theoretical results with our scanning-tunneling-microscopy and photoemission measurements, we identify novel (2x1) surface structures, which are composed of symmetric Bi-Bi and asymmetric mixed Bi-As and Bi-P dimers, and find that they are stabilized by stress relief and pseudogap formation.

Coerced mechanical coarsening of nanoparticle assemblies.

Coarsening is a ubiquitous phenomenon that underpins countless processes in nature, including epitaxial growth, the phase separation of alloys, polymers and binary fluids, the growth of bubbles in foams, and pattern formation in biomembranes. Here we show, in the first real-time experimental study of the evolution of an adsorbed colloidal nanoparticle array, that tapping-mode atomic force microscopy (TM-AFM) can drive the coarsening of Au nanoparticle assemblies on silicon surfaces. Although the growth exponent has a strong dependence on the initial sample morphology, our observations are largely consistent with modified Ostwald ripening processes. To date, ripening processes have been exclusively considered to be thermally activated, but we show that nanoparticle assemblies can be mechanically coerced towards equilibrium, representing a new approach to directed coarsening. This strategy enables precise control over the evolution of micro- and nanostructures.

Airborne occupational allergic contact dermatitis from triglycidyl-p-aminophenol and tetraglycidyl-4,4'-methylene dianiline in preimpregnated epoxy products in the aircraft industry.

BACKGROUND: Very little is known about allergic contact dermatitis (ACD) from preimpregnated epoxy products (prepregs). OBJECTIVE: To describe a patient with occupational ACD from prepregs, and report new quantitative data on the content of prepregs. METHODS AND RESULTS: A laminator developed work-related vesicular hand dermatitis. He worked in an aircraft plant assembling aircraft parts, being exposed to preimpregnated carbon fiber and fiberglass sheets (prepregs), and epoxy adhesive tapes and foams. Triglycidyl-p-aminophenol (TGPAP; 1-0.25%, 2+; 0.05%, 1+) and tetraglycidyl-4,4'-methylene dianiline (TGMDA; 1%, 3+; 0.5-0.05%, 2+) provoked allergic patch test reactions, whereas o-diglycidyl phthalate was negative (1-0.05% pet) and standard epoxy provoked a weak (?+) reaction. Six prepreg products provoking allergic patch test reactions were analyzed for their TGPAP, TGMDA and diglycidyl ether of bisphenol A (DGEBA) content using gas and liquid chromatographic methods, showing up to 10% of TGPAP, 19% of TGMDA and 5% of DGEBA in the prepregs. An epoxy primer contained 61% of TGPAP. CONCLUSION: TGPAP and TGMDA caused occupational ACD. These chemicals need to be used when patch testing patients are exposed to prepregs, because patch testing with DGEBA may be negative.

A feasibility study of realtime teledermatology in Finland.

We conducted a feasibility study of teleconsultation in dermatology using low-cost equipment. Patients and their general practitioners took part in consultations from the Primary Health Care Centre in Ikaalinen with a dermatologist 55 km away at the Tampere University Hospital (TAUH). Consultations were performed using standard commercial videoconferencing equipment, a modified document camera and a dermatoscope. A single ISDN line (128 kbit/s) was used for the connection. During the eight months of the study, 25 patients participated in a teledermatology consultation. Their mean age was 45 years (range 4-92). The average time the patient spent in travelling to the videoconsultation (i.e. one way) was 24 min (range 5-65 min). The mean time spent in the teleconsultation was 15 min (range 5-30 min). After the teleconsultation, patients' treatments changed in 19 cases (76%), diagnoses were changed in 13 cases (52%) and 18 patients (72%) did not need to go to the TAUH. The equipment was generally reliable and easy to use. However, the dermatoscope was not very useful and only one of the consultations relied mainly on it. The cost of the teleconsultations for the 18 patients who avoided travel to the TAUH was FM18,627. The total costs for the 18 conventional consultations in the TAUH would have been FM18,034. The main economic benefits of the videoconferencing were attributable to the reduced travelling and hospital costs. The economic benefits of medical education were more difficult to quantify.

Reactivity of tixocortol pivalate-positive patients in intradermal and oral provocation tests.

Pivalone/tixocortol pivalate commonly yields positive reactions in the patch test series. The clinical relevance of these positive reactions was investigated in more detail. In the standard patch test series 5.6% (73 of 1306) of the patients were positive to corticosteroids, 5.2% to 0.1% tixocortol pivalate in ethanol (Pivalone nasal spray diluted 1:10) and 2.3% to 1% hydrocortisone butyrate in ethanol. Some of the patients were tested in parallel with Pivalone and 1% tixocortol pivalate in petrolatum. The former test reagent yielded some false-positive reactions, whereas with the latter, some allergic responses were missed. Intradermal tests with the succinate esters of hydrocortisone, methylprednisolone and prednisolone were performed with 52 patients positive to Pivalone. Of these 76.9% (40 of 52) were positive in the intradermal tests; 38 to hydrocortisone, 35 to methylprednisolone and 30 to prednisolone. Twelve patients who had been positive in the intradermal tests were challenged orally with corticosteroids and they all showed positive reactions to hydrocortisone, methylprednisolone or prednisolone. The patients developed localized reactions at the sites of previous eczema or positive skin tests or diffuse erythema or exanthema. The oral doses of hydrocortisone eliciting positive delayed skin reactions ranged from 20 to 200 mg. Reactivity to tixocortol pivalate is closely related to sensitivity to hydrocortisone, methylprednisolone and prednisolone, but high oral doses of these corticosteroids may be required to produce allergic symptoms.

Diagnostic value of the lymphocyte proliferation test in nickel contact allergy and provocation in occupational coin dermatitis.

The lymphocyte proliferation test (LPT) was compared with the patch test in the diagnosis of nickel contact sensitivity. Of the 21 subjects with nickel contact allergy, the patch test detected 20 (95%). The subject remaining negative in the patch test was positive in the intradermal test. 18/21 subjects with nickel contact sensitivity were positive in the LPT, whereas in the control group 2/23 subjects were false positive. These results were obtained at nickel sulfate concentrations of less than 10 micrograms/ml, higher concentrations led to nonspecific lymphocyte stimulation. 3 nickel-sensitive cashiers with suspected coin contact-induced deterioration of their hand eczema were challenged by having them count nickel-containing coins daily for 15 min. 2 of them developed vesicular eczema on their palms and fingers in 2 to 3 days. The present results show that the LPT is a reliable additional test in the diagnosis of nickel contact sensitivity. Furthermore, provocation is a valuable procedure when assessing the relevance of nickel contact in occupational hand eczema in certain occupations.

A study of bone formation in osteoma cutis employing biochemical, histochemical and in situ hybridization techniques.

A female presenting multiple osteoma cutis lesions without underlying endocrinological disturbance was studied. Histologically, lesions revealed true bone formation with multiple osteoblastic cells. This was confirmed by demonstrating high alkaline phosphatase activity and osteonectin expression in osteoma cutis lesions. Interestingly, tenascin and type III procollagen were in close association to bony lesions, indicating that these matrix proteins may be somehow involved in bone formation. In situ hybridization revealed fibroblastic cells around bony lesions, which actively deposited type I collagen and osteonectin. One of the activators of bone formation, TGF beta, was also present in some osteoblastic cells. The results thus indicate that in osteoma cutis, fibroblasts have the ability to differentiate into osteoblastic cells, which have some properties of osteoblasts, such as high alkaline phosphatase activity and a high expression of osteonectin.

Osteomyelitis-like bone lesions in acne fulminans.

Two young males with acne fulminans (AF) are described. In addition to severe skin lesions, they had musculoskeletal symptoms including bacteriologically negative osteolytic lesions in the clavicles. Both patients received antibiotics for suspected septic infections. The response was unsatisfactory in both patients, and combination treatment with prednisolone was started. A favourable response was observed, and a relapse occurring in the first patient was controlled by steroids alone. The possible pathomechanism of bone lesions in AF is discussed.

Desmoplastic trichoepithelioma: clinico-pathological features and immunohistochemical study of the basement membrane proteins, laminin and type IV collagen.

Six desmoplastic trichoepitheliomas (DT) from four patients were studied immunohistochemically, using antibodies to the human PI fragment of laminin and the 7S domain of type IV collagen. The staining of the basement membrane around the tumour clusters was distinct and continuous in most areas, but there were discontinuities and a granular appearance of the basement membrane in the areas of keratinized cysts and calcification around some unorganized epithelial cell nests. The discontinuities of the basement membranes may be a sign of epithelial degeneration or altered differentiation rather than malignancy.