Optical net gain measurement on Al0.07Ga0.93N/GaN multi-quantum wells.

We report net gain measurements at room temperature in Al0.07Ga0.93N/GaN 10-period multi-quantum well layers emitting at 367 nm, using the variable stripe length method. The separate confinement heterostructure was designed targeting electron-beam pumped lasing at 10 kV. The highest net gain value was 131 cm-1, obtained at the maximum pumping power density of the experimental setup (743 kW/cm2). The net gain threshold was attained at 218 kW/cm2 using 193 nm optical pumping. From these experiments, we predict an electron-beam-pumped lasing threshold of 370 kW/cm2 at room temperature, which is compatible with the use of compact cathodes (e.g. carbon nanotubes). In some areas of the sample, we observed an anomalous amplification of the photoluminescence intensity that occurs for long stripe lengths (superior to 400 µm) and high pumping power (superior to 550 kW/cm2), leading to an overestimation of the net gain value. We attribute such a phenomenon to the optical feedback provided by the reflection from cracks, which were created during the epitaxial growth due to the strong lattice mismatch between different layers.

AlGaN/GaN asymmetric graded-index separate confinement heterostructures designed for electron-beam pumped UV lasers.

We present a study of undoped AlGaN/GaN separate confinement heterostructures designed to operate as electron beam pumped ultraviolet lasers. We discuss the effect of spontaneous and piezoelectric polarization on carrier diffusion, comparing the results of cathodoluminescence with electronic simulations of the band structure and Monte Carlo calculations of the electron trajectories. Carrier collection is significantly improved using an asymmetric graded-index separate confinement heterostructure (GRINSCH). The graded layers avoid potential barriers induced by polarization differences in the heterostructure and serve as strain transition buffers which reduce the mosaicity of the active region and the linewidth of spontaneous emission.

Giant osmotic energy conversion measured in a single transmembrane boron nitride nanotube.

New models of fluid transport are expected to emerge from the confinement of liquids at the nanoscale, with potential applications in ultrafiltration, desalination and energy conversion. Nevertheless, advancing our fundamental understanding of fluid transport on the smallest scales requires mass and ion dynamics to be ultimately characterized across an individual channel to avoid averaging over many pores. A major challenge for nanofluidics thus lies in building distinct and well-controlled nanochannels, amenable to the systematic exploration of their properties. Here we describe the fabrication and use of a hierarchical nanofluidic device made of a boron nitride nanotube that pierces an ultrathin membrane and connects two fluid reservoirs. Such a transmembrane geometry allows the detailed study of fluidic transport through a single nanotube under diverse forces, including electric fields, pressure drops and chemical gradients. Using this device, we discover very large, osmotically induced electric currents generated by salinity gradients, exceeding by two orders of magnitude their pressure-driven counterpart. We show that this result originates in the anomalously high surface charge carried by the nanotube's internal surface in water at large pH, which we independently quantify in conductance measurements. The nano-assembly route using nanostructures as building blocks opens the way to studying fluid, ionic and molecule transport on the nanoscale, and may lead to biomimetic functionalities. Our results furthermore suggest that boron nitride nanotubes could be used as membranes for osmotic power harvesting under salinity gradients.

Lichen Planus With Predominate Plasma Cell Infiltrate: Two Case Reports.

Lichen planus (LP) is a mucocutaneous inflammatory dermatitis of idiopathic origin that can involve the skin, mucous membranes, hair, and nails. LP has an associated set of characteristic histopathologic findings which include hyperkeratosis, vacuolization of the basal layer, Civatte bodies, wedge-shaped hypergranulosis, band-like lymphocytic infiltrate at the dermal epidermal junction, eosinophilic colloid bodies in the papillary dermis, and pigment incontinence. The infiltrate is usually composed of lymphocytes with few histiocytes, mast cells, and macrophages. The presence of plasma cell predominant infiltrate in LP has only been reported in four previous cases and 2 other cases of lichen nitidus. The authors report another 2 cases of LP with predominate plasma cell infiltrate in 2 female patients on the legs. The differential includes a drug-induced lichenoid reaction with predominate plasma cell infiltrate. However, there have been no case reports of that type of reaction. Because plasma cells are seen commonly in certain infectious diseases, malignancy, and macroglobulinemia, it is prudent to rule out those entities. Our patients responded well with a class 1 topical steroid, with improvement of their lower leg lesions within 1 month of treatment.

Arthroscopic Suprapectoral and Open Subpectoral Biceps Tenodesis: Radiographic Characteristics.

PURPOSE: To provide a detailed account of the location of the long head of the biceps (LHB) tenodesis tunnels using an all-arthroscopic suprapectoral technique in a prospective group of patients. These patients were then compared with a retrospective group of open subpectoral tenodesis patients of similar characteristics. METHODS: Postoperative radiographs from a prospective group of all-arthroscopic suprapectoral LHB tenodeses were compared with a retrospective group of open subpectoral tenodeses. Digital anteroposterior images were used to measure distances from clinically pertinent radiographic landmarks to tenodesis tunnel sites. RESULTS: Forty patients (20 all-arthroscopic, 20 open) met the inclusion criteria. The inferior border of the bicipital groove was located a mean distance of 33.7 ± 6.9 mm from the top of the humeral head. The mean distance measured in the open group was approximately 28 mm (P < .001) distal compared with the arthroscopic group. The humeral diameter was 7.5 ± 5.4 mm narrower at the subpectoral tenodesis site (P < .001). All 20 patients in the open subpectoral group had tenodesis tunnels placed distal to the bicipital groove compared with 17 of 20 patients (85%) in the all-arthroscopic group. There were 2 cases of lateral wall cortical reaming during subpectoral tenodesis but no periprosthetic humeral fractures. There were 2 cases of bicortical reaming during the all-arthroscopic tenodesis with no known complications. CONCLUSIONS: The location of biceps tenodesis significantly differs between all-arthroscopic suprapectoral and open subpectoral techniques, and the open subpectoral method achieves fixation in a significantly narrower region of the humerus. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

High frequency top-down junction-less silicon nanowire resonators.

We report here the first realization of top-down silicon nanowires (SiNW) transduced by both junction-less field-effect transistor (FET) and the piezoresistive (PZR) effect. The suspended SiNWs are among the smallest top-down SiNWs reported to date, featuring widths down to ~20 nm. This has been achieved thanks to a 200 mm-wafer-scale, VLSI process fully amenable to monolithic CMOS co-integration. Thanks to the very small dimensions, the conductance of the silicon nanowire can be controlled by a nearby electrostatic gate. Both the junction-less FET and the previously demonstrated PZR transduction have been performed with the same SiNW. These self-transducing schemes have shown similar signal-to-background ratios, and the PZR transduction has exhibited a relatively higher output signal. Allan deviation (σA) of the same SiNW has been measured with both schemes, and we obtain σ(A) ~ 20 ppm for the FET detection and σ(A) ~ 3 ppm for the PZR detection at room temperature and low pressure. Orders of magnitude improvements are expected from tighter electrostatic control via changes in geometry and doping level, as well as from CMOS integration. The compact, simple topology of these elementary SiNW resonators opens up new paths towards ultra-dense arrays for gas and mass sensing, time keeping or logic switching systems on the SiNW-CMOS platform.

Cutaneous Manifestations of Nutritional Deficiencies in the Context of Food Deserts of United States.

Food deserts exist due to a multitude of factors ranging from socioeconomic status, racial disparities, geography, cost, and healthful food access. Given the vast biological function of vitamins and minerals, the clinical presentation for nutritional deficiencies ranges from benign to life-threatening. Often, the first indicators of underlying nutritional deficiencies are cutaneous manifestations. The first patient case is a 36-year-old female at 25 weeks gestation with a pruritic and painful rash that began in the genital region and spread centrifugally to her legs. The second patient case is a 42-year-old male with a pruritic rash that began at his abdomen and progressed to his thighs. The third patient case is a 48-year-old female with scattered lower extremity ecchymoses in different healing stages and scattered perifollicular erythema with corkscrew hairs. All three patients were found to have nutritional deficiencies and lived in identified food deserts. Deficiencies of zinc, vitamin A, thiamine, pyridoxine, and vitamin C and their subsequent cutaneous manifestations have scarce documentation within food deserts. These cases provide further insight into nutritional deficiencies and offer an opportunity for providers to identify patients at risk. To promote wellness, patients suffering from food insecurity must be identified efficiently and connected with essential resources.

Nephrogenic Systemic Fibrosis in the Setting of Transient Renal Insufficiency.

Nephrogenic systemic fibrosis (NSF) is a rare disease that can present in patients with kidney injury who have been exposed to gadolinium-based contrast agents (GBCAs). These patients can easily be misdiagnosed as having another disease because they do not fit the usual presentation of being on hemodialysis. We report a case of NSF occurring in a patient with resolved transient renal insufficiency and no history of chronic renal disease.

Digital and FM demodulation of a doubly clamped single-walled carbon-nanotube oscillator: towards a nanotube cell phone.

Electromechanical resonators are a key element in radio-frequency telecommunication devices and thus new resonator concepts from nanotechnology can readily find important industrial opportunities. Here, the successful experimental realization of AM, FM, and digital demodulation with suspended single-walled carbon-nanotube resonators in a field-effect transistor configuration is reported. The crucial role played by the electromechanical resonance in demodulation is clearly demonstrated. The FM technique is shown to lead to the suppression of unwanted background signals and the reduction of noise for a better detection of the mechanical motion of nanotubes. The digital data-transfer rate of standard cell-phone technology is within the reach of these devices.

Growing a carbon nanotube atom by atom: "and yet it does turn".

We use field emission microscopy (FEM) to observe directly the growths of individual carbon nanotubes (CNTs) from the nucleation stage and discover that the CNTs often rotate axially during growth, thus supporting a recently proposed "screw-dislocation-like" (SDL) model. One particularly revealing case is emphasized here in which the CNT turned approximately 180 times during its 11 min growth. Even more remarkable is the frame-by-frame analysis of the video which shows that the rotation proceeds by discrete steps with about approximately 24 per rotation, half the number of atoms on the circumferences of common single wall carbon nanotubes (SWNTs). The conclusion is that we directly observed the SDL growth of a SWNT one carbon dimer at a time. This observation should aid researchers to precisely understand and control the growth of SWNTs.

Psychic Song and Dance: Dissociation and Duets in the Analysis of Trauma.

The author offers observations on the nature of pathological dissociation, emphasizing the compartmentalization of unsymbolized affective experience. The irrelevance of personal agency and intentionality in the pathogenesis of dissociative psychopathology along with the deficiency in symbolization that is a sequela of trauma present special problems for traditional as well as for Relational approaches to technique. To a significant extent, "technique" must be replaced by the analyst's way of being. The author posits, as metaphor and model for this way of being, a notion of "psychoanalytic duets" occurring in the realms of both prosody and action-song and dance. An extended clinical vignette is presented to illustrate these ideas and to point toward a transformational effect of this kind of duetting.

Relapsing polychondritis in human immunodeficiency virus.

Relapsing polychondritis (RP) is an inflammatory condition that has been widely accepted as autoimmune in nature and can occur in patients with immune system dysregulation. Although RP has been well documented in patients with other autoimmune conditions, such as vasculitis, its presence in patients with human immunodeficiency virus (HIV) infection has been infrequently described. We describe a case of RP in an HIV-positive patient without other identifiable autoimmune disease.

Acroangiodermatitis of Mali and Stewart-Bluefarb syndrome.

Acroangiodermatitis (AAD), also known as pseudo-Kaposi sarcoma, is a rare benign vascular proliferation mainly of the extremities. It is characterized by violaceous patches or plaques resembling Kaposi sarcoma. The term pseudo-Kaposi sarcoma encompasses 2 variants of acroangiodermatitis: Mali type and Stewart-Bluefarb syndrome (SBS). Mali-type AAD is more common and is associated with chronic venous hypertension, while SBS is more rare and is associated with arteriovenous malformations and iatrogenic arteriovenous fistulae. We report 2 patients, representing each type of AAD.

Necrobiosis lipoidica with superimposed pyoderma vegetans.

Necrobiosis lipoidica (NL) is a granulomatous inflammatory skin disease strongly associated with diabetes mellitus (DM). Red-brown papules expanding into plaques with erythematous indurated borders on the lower extremities are characteristic of NL. Diagnosis is made clinically; however, biopsy of lesions confirms the diagnosis. Untreated NL may ulcerate and lead to further complications, but progression to superimposed pyoderma vegetans (PV) is not a known occurrence.

The analyst's attitude toward pharmacotherapy.

The increased acceptance of medication in psychoanalysis has occurred with too little consideration of possible complications. The potentially adverse psychological effects and disintegrative aspects of this important technical modification require further examination. While the use of phenomenologically defined diagnostic criteria provides valuable guidance to the clinician, the decision to include pharmacotherapy in a psychoanalysis must be understood also as a transference-countertransference enactment. The analyst's attitude toward pharmacotherapy is an essential element in some defensive and gratifying enactments, resistances that can interfere with psychoanalytic processes. Clinical material is presented illustrating narcissistic and perverse resistances that might be facilitated by analysts' attitudes toward pharmacotherapy, attitudes often tacitly communicated in decisions to use combined treatment.

Spontaneous regression of Merkel cell carcinoma.

A 96-year-old woman presented with a rapidly enlarging lesion overlying the suprasternal notch. The lesion originated as a small, erythematous, scaly macule that rapidly increased in size over 8 weeks and became an ulcerated nodule measuring 5 cm in diameter and 4.5 cm in thickness. A 4-mm punch biopsy showed a poorly differentiated tumor with cells that were positive for CAM 5.2 and cytokeratin 20 in a dotlike paranuclear pattern and negative for cytokeratin 5/6, human melanoma black 45, and leukocyte common antigen. Two weeks after the punch biopsy, the lesion noticeably decreased in size, and within 8 weeks of the biopsy the tumor had completely resolved with no further intervention. Regression of Merkel cell carcinoma (MCC) is a very rare event, with as few as 30 cases reported. The mechanism of this phenomenon remains unclear; however, T-cell-mediated immunity and apoptosis appear to play a major role.

Inflammatory linear verrucous epidermal nevus responsive to 308-nm excimer laser treatment.

Inflammatory linear verrucous epidermal nevus (ILVEN) is a rare cutaneous disease that presents as linear psoriasiform plaques with associated prominent pruritus. The lesions commonly pre-sent on the legs with onset during childhood. Inflammatory linear verrucous epidermal nevus typically is refractory to treatment. Therapies range from topical treatments to lasers and surgical options. It is clinically and histopathologically similar to psoriasis, suggesting it may respond to established psoriasis treatments such as the excimer laser. We report the case of an otherwise healthy 20-year-old woman with dry, pruritic, red lesions on the right leg that had been present since infancy. Biopsy revealed psoriasiform hyperplasia with a verruciform surface. Multiple topical treatments including ablative CO2 laser therapy showed no remarkable improvement. The patient was then treated with a UV 308-nm excimer laser and showed noticeable clinical improvement. Because of its clinical and histopathological similarities to psoriasis, we hypothesized that the excimer laser may be useful in the treatment of these lesions.

Acrokeratoelastoidosis and knuckle pads coexisting in a child.

Acrokeratoelastoidosis (AKE) is a marginal papular keratoderma that typically presents in childhood and young adulthood. Childhood cases have exhibited autosomal-dominant inheritance. Acrokeratoelastoidosis is distinct from other palmoplantar marginal papular keratodermas because of its characteristic dermal elastorrhexis with an overlying epithelial dell. We report an 11-year-old boy with multiple translucent hyperkeratotic papules in a linear fashion on the bilateral palmoplantar surfaces characteristic of AKE. He also presented with knuckle pads on the proximal and distal interphalangeal joints that rarely have been reported with AKE, suggesting that AKE and atraumatic knuckle pads may coexist.