Increase in the random dopant induced threshold fluctuations and lowering in sub-100 nm MOSFETs due to quantum effects: a 3-D density-gradient simulation study

In this paper, we present a detailed simulation study of the influence of quantum mechanical effects in the inversion layer on random dopant induced threshold voltage fluctuations and lowering in sub-100 mn MOSFETs. The simulations have been performed using a three-dimensional (3-D) implementation of the density gradient (DG) formalism incorporated in our established 3-D atomistic simulation approach. This results in a self-consistent 3-D quantum mechanical picture, which implies not only the vertical inversion layer quantization but also the lateral confinement effects related to current filamentation in the “valleys” of the random potential fluctuations. We have shown that the net result of including quantum mechanical effects, while considering statistical dopant fluctuations, is an increase in both threshold voltage fluctuations and lowering. At the same time, the random dopant induced threshold voltage lowering partially compensates for the quantum mechanical threshold voltage shift in aggressively scaled MOSFETs with ultrathin gate oxides

Electron Glass Dynamics

Examples of glasses are abundant, yet it remains one of the phases of matter whose understanding is very elusive. In recent years, remarkable experiments have been performed on the dynamical aspects of glasses. Electron glasses offer a particularly good example of the 'trademarks' of glassy behavior, such as aging and slow relaxations. In this work we review the experimental literature on electron glasses, as well as the local mean-field theoretical framework put forward in recent years to understand some of these results. We also present novel theoretical results explaining the periodic aging experiment.Comment: Invited review to appear in Annual Review of Condensed Matter Physic

The life-cycle and feeding of the African freshwater leech Helobdella conifera (Glossiphoniidae)

The life-cycle, breeding and feeding of the fresh water leech Helobdella conifera were examined in the laboratory. The life-cycle is annual with the young brooded by the parent for the first two months after hatching. Sexual maturity is attained two months after leaving the parent when the first batch of eggs are produced and the young brooded. The number of broods ranges from one to four with the maiority producing three. A few young leeches fed on the snail Helisoma duryi while still attached to the parent but the majority did not feed until 11 days after leaving the parent with 12-23 small (4.0-7.0 mm) snails consumed before producing their first batch of eggs. The life time consumption of small snails ranged from 26-60 with no correlation between the numbers of snails consumed and the numbers of broods or the numbers of progeny. Leeches only fed on small, live H. duryi and did not feed on large (10.0-13.0 mm) individuals although they fed as scavengers on dead large snails. A strong preference was exhibited by H. conifera for small H. duryi compared to small P acuta with the most of the feeding occurring in the dark.S. Afr. J. Zool. 1997, 32(1

Non-invasive assessment of peripheral arterial disease: Automated ankle brachial index measurement and pulse volume analysis compared to duplex scan

Objectives: This cross-sectional study aimed to individually and cumulatively compare sensitivity and specificity of the (1) ankle brachial index and (2) pulse volume waveform analysis recorded by the same automated device, with the presence or absence of peripheral arterial disease being verified by ultrasound duplex scan. Methods: Patients (n=205) referred for lower limb arterial assessment underwent ankle brachial index measurement and pulse volume waveform recording using volume plethysmography, followed by ultrasound duplex scan. The presence of peripheral arterial disease was recorded if ankle brachial index 50% was evident with ultrasound duplex scan. Outcome measure was agreement between the measured ankle brachial index and interpretation of pulse volume waveform for peripheral arterial disease diagnosis, using ultrasound duplex scan as the reference standard. Results: Sensitivity of ankle brachial index was 79%, specificity 91% and overall accuracy 88%. Pulse volume waveform sensitivity was 97%, specificity 81% and overall accuracy 85%. The combined sensitivity of ankle brachial index and pulse volume waveform was 100%, specificity 76% and overall accuracy 85%. Conclusion: Combining these two diagnostic modalities within one device provided a highly accurate method of ruling out peripheral arterial disease, which could be utilised in primary care to safely reduce unnecessary secondary care referrals

Quantum Mechanical Enhancement of Random Dopant Induced Threshold Voltage Fluctuations and Lowering in Sub 0.1 micron MOSFETs

Published versio

Experimental investigation of multi-step stress-relaxation-ageing of 7050 aluminium alloy for different pre-strained conditions

A novel insight into the whole two-step stress relaxation ageing process during T74 multi–step ageing treatment (120 °C for 6 h and subsequently 177 °C for 7 h), which is typically experienced by extra-large aircraft components that contain high residual stresses, has been established. Stress relaxation ageing (SRA) tests, tensile tests and transmission electron microscopy (TEM) were performed on AA7050 samples to determine the relationship between internal microstructure and macroscopic behaviour during the stress relaxation and precipitate evolution process. Samples were subjected to SRA at different initial stresses (220–360 MPa) after being pre-strained to different extents (i.e. 0%, 1%, 3%). Room temperature tensile tests were then performed on interrupted SRA test specimens to examine the corresponding strengthening phenomenon. TEM was performed on a selection of peak–aged and T74 over–aged samples to study the precipitate distribution. At 120 °C typical stress relaxation behaviour was observed and the data follow ed a logarithmic curve. Subsequently at 177 °C, dislocation–creep dominated stress relaxation behaviour, with no apparent threshold stress, was observed. The absence of a threshold stress at 177 °C may be attributed to the continuous over-ageing phenomenon. The effect of pre-deformation levels and initial stresses on SRA has also been investigated. Pre-stretching, which creates uniformly distributed dislocations, promotes stress relaxation and ageing. No significant influence of initial stress level on SRA was observed at 120 °C, but noticeable effects were seen at 177 °C. The calculated stress exponent n at 177 °C is found independent of the initial stresses. These findings provide clear scientific guidance for residual stress reduction during the multi-step ageing process of AA7050 and provide the basis for residual stress prediction models

Christian Counsellors' Views on Working with Gay and Lesbian Clients:Integrating Religious Beliefs with Counselling Ethics

Thirty-one counsellors who identified themselves as practising, committed Christians, returned completed questionnaires that investigated how they integrate their Christian beliefs with their professional ethical code when counselling gay and lesbian clients. It was found that although most respondents believed that they were able to accept gay and lesbian clients, a minority demonstrated incongruence in relation to members of this client group, and were judgmental about perceived gay/lesbian behavious. Counsellors who took a rational stance in their understanding of the Bible and Christianity expressed more open and accepting views. Counsellors with a literalist approach to the Bible appeared to be lacking in acceptance and were unaware that they may not be offering the core condition of respect to their gay or lesbian clients. These findings are discussed in terms of their implications for supervision, research and practice