The effects of electrochemically-induced etching non-uniformitieson microwave field effect transistors

For the first time, direct experimental evidence of the electrochemical etching component, associated with wet chemical etching of semiconductor devices, is shown to produce significant non-uniformities in device (e.g. material) characteristics. Furthermore, it is shown that these electrochemically-induced non-uniformities (within the device itself) can significantly reduce RF performance of power microwave devices. Comparative microwave measurements between discrete power devices that had, or did not have, electrochemically-induced non-uniformities, clearly demonstrated marked differences in device power-added efficiency (PAE)     

Modulated S-parameter measurements for isothermal microwave devicecharacterization

The validity of extracted microwave device models is critically dependent on the completeness, accuracy, and appropriateness of the starting device characterization data. In this letter we will present a novel technique for determining the S-parameters of a device under isothermal (i.e., no heating) operation. Additionally, this technique can be applied to determining the CW S-parameters under more extreme (e.g., forward bias/breakdown) operation. By pulse-biasing the device from the “OFF” to the “ON” state, while performing standard S-parameter measurements, resultant data is found to be characteristic of the weighted (by duty factor) scalar sum of the devices “ON”-state and “OFF”-state S-parameter(s). We will show how these measurements can then be used to interpret the devices isothermal CW S-parameters     

Getting closer: tailored human–computer speech dialog

This paper presents an advanced call center, which adapts presentation and interaction strategy to properties of the caller such as age, gender, and emotional state. User studies on interactive voice response (IVR) systems have shown that these properties can be used effectively to “tailor” services to users or user groups who do not maintain personal preferences, e.g., because they do not use the service on a regular basis. The adopted approach to achieve individualization of services, without being able to personalize them, is based on the analysis of a caller’s voice. This paper shows how this approach benefits service providers by being able to target entertainment and recommendation options. It also shows how this analysis at the same time benefits the customer, as it can increase accessibility of IVR systems to user segments which have particular expectations or which do not cope well with a “one size fits all” system. The paper summarizes the authors’ current work on component technologies, such as emotion detection, age and gender recognition on telephony speech, and presents results of usability and acceptability tests as well as an architecture to integrate these technologies in future multi-modal contact centers. It is envisioned that these will eventually serve customers with an avatar representation of an agent and tailored interaction strategies, matching powerful output capabilities with advanced analysis of the user’s input.

RF energy scavenging system utilising switched capacitor DC-DC converter

An RF energy scavenging circuit implementing a power matched Villard voltage doubler followed by a switched capacitor DC-DC converter for scavenging ultra-low RF power levels (20 dBm) is presented. Measurement results for the circuit, fabricated in a 130 nm CMOS process, show that 1 V can be generated across a 5 M load from as little as 25.5 Bm of input RF energy at 2.2 GHz. This represents a 9.5 dB improvement, over the measured sensitivity of our RF energy scavenging circuit without the use of a switched capacitor DC-DC converter stage.     

Impaired cutaneous immune responses in Thy-1-deficient mice

Thy-1 is a cell surface glycoprotein expressed mainly on brain and lymphoid tissue. Although the functions of Thy-1 are incompletely understood, evidence exists that Thy-1 participates in T cell activation. To examine the functional role of Thy-1 in cutaneous immune responses in vivo, Thy-1 gene-targeted mice (Thy-1-/-) and wild-type mice (Thy-1+/+) were immunized with the hapten oxazolone. After challenge with oxazolone, contact hypersensitivity responses in Thy-1-/- mice were reduced by 25% compared with Thy-1+/+ mice. Likewise, irritant dermatitis induced by croton oil was also decreased. In addition, Thy-1-/- mice showed a significantly reduced delayed-type hypersensitivity response after injection of allogeneic spleen cells into the hind footpads of allosensitized animals when compared with Thy-1+/+ mice. Moreover, proliferative responses to immobilized anti-CD3 were decreased in peripheral Thy-1-/- lymphocytes; this decrease was associated with a significantly reduced intracellular Ca2+ influx and protein tyrosine phosphorylation, indicating impairment of early lymphocyte activation. In contrast, the T cell proliferation induced by mitogens was normal, suggesting that Thy-1 expression weakly contributes to TCR-mediated T cell activation. Epidermal Langerhans cells and bone marrow-derived dendritic cells from Thy-1-/- mice exhibited a normal expression of costimulatory surface molecules as well as an unaltered ability to stimulate allogeneic T cells. Taken together, these findings demonstrate that a lack of Thy-1 expression does not generally compromise the immune system; however, Thy-1 expression may be involved in the fine-tuning of T cell-mediated immune responses.     

Molluscum contagiosum-like papules within the scope of disseminated infection with Mycobacterium avium complex in an AIDS patient

A 38-year-old HIV-positive man had several attacks of high fever associated with extensive perspiration over a 10-week period. Simultaneously, he developed molluscum contagiosum-like papules and an erythematous plaque on the face, ulcerated papules on both shoulders and buttocks and subcutaneous nodules on the arms. Histological examination of biopsy specimens revealed a diffuse, histiocytic infiltrate with abundant rod-shaped bacteria. Mycobacterium avium complex was cultured from the tissue and Mycobacterium avium complex DNA was detected by the polymerase chain reaction. The diagnosis of disseminated disease was additionally confirmed by culturing Mycobacterium avium complex from blood, sputum and stool. The skin lesions healed completely within 10 weeks by a multiagent as the patient was treated with a drug therapy. We describe the differential diagnosis, diagnostic procedures and therapy of disseminated infection with Mycobacterium avium complex.