bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic scattering by a metallic tube with a concentric solid polymer cylinder coupled by a thin water layer. Influence of the thickness of the water layer on the two Scholte–Stoneley waves
Authors: Chati Farid , Léon Fernand , Maze Gérard
Published: October 2005

The problem of a plane acoustic wave scattered by a layered cylinder submerged in water is considered. This cylinder consists of a tube made of aluminum with a solid Lucite cylinder concentrically fitt inside it. These two components are coupled by a thin layer of water. A particular investigation is made on the influence of the thickness of the water layer on the presence of the bending wave A on the tube and the Scholte–Stoneley wave on the cylinder. The presence of these waves is examined in the function of the varying water layer thickness: two special cases are discussed. First, for a layer thickness greater than the tube thickness, it is shown that both the A wave on the aluminum tube and the Scholte–Stoneley wave on the Lucite cylinder are generated. Second, for a thickness much smaller than the tube thickness, a different wave is generated, which is a combination of both waves. These two cases are experimentally verified in a setup that employs a short pulse method.
Subspace algorithms for noise reduction in cochlear implants
Authors: Loizou Philipos C. , Lobo Arthur , Hu Yi
Published: October 2005

A single-channel algorithm is proposed for noise reduction in cochlear implants. The proposed algorithm is based on subspace principles and projects the noisy speech vector onto “signal” and “noise” subspaces. An estimate of the clean signal is made by retaining only the components in the signal subspace. The performance of the subspace reduction algorithm is evaluated using 14 subjects wearing the Clarion device. Results indicated that the subspace algorithm produced significant improvements in sentence recognition scores compared to the subjects’ daily strategy, at least in stationary noise. Further work is needed to extend the subspace algorithm to nonstationary noise environments.
Thresholds for second formant transitions in front vowels
Authors: Kewley-Port Diane , Goodman Shawn S.
Published: October 2005

Formant dynamics in vowel nuclei contribute to vowel classification in English. This study examined listeners’ ability to discriminate dynamic second formant transitions in synthetic high front vowels. Acoustic measurements were made from the nuclei (steady state and 20% and 80% of vowel duration) for the vowels ∕i,I,e,ε,æ∕ spoken by a female in ∕bVd∕ context. Three synthesis parameters were selected to yield twelve discrimination conditions: initial frequency value for F2 (2525, 2272, or 2068 Hz), slope direction (rising or falling), and duration (110 or 165 ms). F1 frequency was roved. In the standard stimuli, F0 and F1–F4 were steady state. In the comparison stimuli only F2 frequency varied linearly to reach a final frequency. Five listeners were tested under adaptive tracking to estimate the threshold for frequency extent, the minimal detectable difference in frequency between the initial and final F2 values, called ΔF extent. Analysis showed that initial F2 frequency and direction of movement for some F2 frequencies contributed to significant differences in ΔF extent. Results suggested that listeners attended to differences in the stimulus property of frequency extent (hertz), not formant slope (hertz∕second). Formant extent thresholds were at least four times smaller than extents measured in the natural speech tokens, and 18 times smaller than for the diphthongized vowel ∕e∕.
The temporal effect in listeners with mild to moderate cochlear hearing impairment
Authors: Strickland Elizabeth A. , Krishnan Lata A.
Published: October 2005

This study examines the relationship between a temporal masking effect and cochlear hearing impairment. The threshold level of a long-duration broadband masker needed to mask a short-duration tonal signal was measured for signals presented 2 ms (short-delay) or 202 ms (long-delay condition) after masker onset. The difference between these thresholds is the temporal effect. In two previous studies with normal-hearing listeners, estimates of gain of the cochlear active process derived from such data suggested a decrease in gain during the course of the masker. This hypothesis was further examined in the present study by testing listeners with mild to moderate cochlear hearing impairment. Results are consistent with a decrease in gain in the short-delay condition with increasing hearing impairment, and also less change in gain with increasing hearing impairment.
Energy sinks: Vibration absorption by an optimal set of undamped oscillators
Authors: Koç I. Murat , Carcaterra Antonio , Xu Zhaoshun , Akay Adnan
Published: October 2005

This paper describes a new concept referred to here as “energy sinks” as an alternative to conventional methods of vibration absorption and damping. A prototypical energy sink envisioned here consists of a set of oscillators attached to, or an integral part of, a vibrating structure. The oscillators that make up an energy sink absorb vibratory energy from a structure and retain it in their phase space. In principle, energy sinks do not dissipate vibratory energy as heat in the classical sense. The absorbed energy remains in an energy sink permanently (or for sufficiently long durations) so that the flow of energy from the primary structure appears to it as damping. This paper demonstrates that a set of linear oscillators can collectively absorb and retain vibratory energy with near irreversibility when they have a particular distribution of natural frequencies. The approach to obtain such a frequency distribution is based on an optimization that minimizes the energy retained by the structure as a function of frequency distribution of the oscillators in the set. The paper offers verification of such optimal frequency spectra with numerical simulations and physical demonstrations.
FULL-STATE TRACKING CONTROL OF A MOBILE ROBOT USING NEURAL NETWORKS
Authors: CHAITANYA V. SREE KRISHNA
Published: October 2005

In this paper a nonholonomic mobile robot with completely unknown dynamics is discussed. A mathematical model has been considered and an efficient neural network is developed, which ensures guaranteed tracking performance leading to stability of the system. The neural network assumes a single layer structure, by taking advantage of the robot regressor dynamics that expresses the highly nonlinear robot dynamics in a linear form in terms of the known and unknown robot dynamic parameters. No assumptions relating to the boundedness is placed on the unmodeled disturbances. It is capable of generating real-time smooth and continuous velocity control signals that drive the mobile robot to follow the desired trajectories. The proposed approach resolves speed jump problem existing in some previous tracking controllers. Further, this neural network does not require offline training procedures. Lyapunov theory has been used to prove system stability. The practicality and effectiveness of the proposed tracking controller are demonstrated by simulation and comparison results.
SYMMETRIES OF THE GALACTIC FOREGROUNDS IN THE WMAP DATA
Authors: NASELSKY PAVEL D. , NOVIKOV IGOR D.
Published: October 2005

We present a specific periodicity of the Galaxy images in the multipole domain which can be used to separate the cosmic microwave background (CMB) signal from the Galaxy and foreground component. This method takes into consideration all the coefficients of the expansion of the signal from the sky ΔT(Θ,ϕ) into spherical harmonics and dealing with combination of multipoles al,m and al+Δ,m for each multipole mode (ℓ, -ℓ ≤ m ≤ ℓ) from the whole sky without galactic cut, masks or any dissection of the whole sky into disjoint regions. For the polar coordinate system we use particular values for Δ = 4n, n = 1, 2,… which remove all bright pointlike sources that are localized in the Galactic plane and strong diffused component down to the CMB level. To illustrate the significant correlations of the pointlike sources and the foregrounds al,m, al+Δ,m coefficients we apply this method to the WMAP Q, V and W bands in order to remove these marks of the Galaxy from the maps. We believe that our method would be useful for separating the CMB signal from different kind of "noises" in the maps.
INCREMENTAL TECHNICAL INNOVATIONS AND THEIR DETERMINANTS
Authors: MADANMOHAN T. R.
Published: October 2005

Incremental technical innovation is one of the significant dynamic processes taking place in manufacturing firms. For this study, incremental technical innovation has been classified as material, operations, scale and product innovations and we contend that their source and efforts directed are different and therefore it is imperative to identify the predictors of each. Based on a field study of 83 manufacturing firms in India, the study has found that government policies, customer orientation and formalisation are the predictors of material innovations. Operational innovations are related to inter-functional coordination, process orientation, centralisation and annual demand of the product. Customer orientation and formalisation are the predictors of scale innovations. Finally, incremental product innovations are related to technology planning and R&D intensity.
Ritual Rewards: A Consideration of Three Recent Approaches to Sunni Purity Law
Authors: Gauvain Richard
Published: October 2005

In an effort to raise interest in the subject of Islam's ritual legal material, I discuss here the strengths and weaknesses of three recent studies of Sunni Islamic purity law (taharah). In light of these studies, I investigate the degree to which theories and models drawn from the fields of anthropology and comparative religion may be said to shed light on Islamic ritual law and practice. As—to varying degrees—each of my selected authors contests the theories of cultural anthropologist Mary Douglas, special attention is paid to her work. My own opinion is that, as long as we proceed cautiously, an awareness of anthropological approaches and cross-cultural data, such as that proposed by Douglas, can be helpful in understanding (the uniqueness of) Islamic ritual law; and that there are wide-ranging benefits for students of Islam, anthropology and comparative religion in doing just this.
Fitting an Exponential Distribution
Authors: Fraile Roberto , García-Ortega Eduardo
Published: October 2005

Exponential distributions of the type N = N0 exp(−λt) occur with a high frequency in a wide range of scientific disciplines. This paper argues against a widely spread method for calculating the λ parameter in this distribution. When the ln function is applied to both members, the equation of a straight line in t is obtained, which may be fit by means of linear regression. However, the paper illustrates that this is equivalent to a least squares fit with a weight function that assigns more importance to the higher values of t. It is argued that the method of maximum likelihood should be applied, because it takes into account all of the data equally. An iterative method for determining λ is proposed, based on the method of moments for cases in which only a truncated distribution is available.
Effect of Temporal Sampling on Inferred Rainfall Spatial Statistics
Authors: Gebremichael Mekonnen , Krajewski Witold F.
Published: October 2005

On the basis of temporally sampled data obtained from satellites, spatial statistics of rainfall can be estimated. In this paper, the authors compare the estimated spatial statistics with their “true” or ensemble values calculated using 5 yr of 15-min radar-based rainfall data at a spatial domain of 512 km × 512 km in the central United States. The authors conducted a Monte Carlo sampling experiment to simulate different sampling scenarios for variable sampling intervals and rainfall averaging periods. The spatial statistics used are the moments of spatial distribution of rainfall, the spatial scaling exponents, and the spatial cross correlations between the sample and ensemble rainfall fields. The results demonstrated that the expected value of the relative error in the mean rain-rate estimate is zero for rainfall averaged over 5 days or longer, better temporal sampling produces average fields that are “less noisy” spatially, an increase in the sampling interval causes the sampled rainfall to be increasingly less correlated with the true rainfall map, and the spatial scaling exponent estimators could give a bias of 40% or less. The results of this study provide a basis for understanding the impact of temporal statistics on inferred spatial statistics.
Climatology of the Low-Level Jet at the Southern Great Plains Atmospheric Boundary Layer Experiments Site
Authors: Song Jie , Liao Ke , Coulter Richard L. , Lesht Barry M.
Published: October 2005

A unique dataset obtained with combinations of minisodars and 915-MHz wind profilers at the Atmospheric Boundary Layer Experiments (ABLE) facility in Kansas was used to examine the detailed characteristics of the nocturnal low-level jet (LLJ). In contrast to instruments used in earlier studies, the ABLE instruments provide hourly, high-resolution vertical profiles of wind velocity from just above the surface to approximately 2 km above ground level (AGL). Furthermore, the 6-yr span of the dataset allowed the examination of interannual variability in jet properties with improved statistical reliability. It was found that LLJs occurred during 63% of the nighttime periods sampled. Although most of the observed jets were southerly, a substantial fraction (28%) was northerly. Wind maxima occurred most frequently at 200–400 m AGL, though some jets were found as low as 50 m, and the strongest jets tended to occur above 300 m. Comparison of LLJ heights at three locations within the ABLE domain and at one location outside the domain suggests that the jet is equipotential rather than terrain following. The occurrence of southerly LLJ varied annually in a way that suggests a connection between the tendency for jet formation and the large-scale circulation patterns associated with El Niño and La Niña, as well as with the Pacific decadal oscillation. Frequent and strong southerly jets that transport moisture downstream do not necessarily lead to more precipitation locally, however.
The IMPROVE-1 Storm of 1–2 February 2001. Part II: Cloud Structures and the Growth of Precipitation
Authors: Evans Amanda G. , Locatelli John D. , Stoelinga Mark T. , Hobbs Peter V.
Published: October 2005

On 1–2 February 2001, a strong cyclonic storm system developed over the northeastern Pacific Ocean and moved onto the Washington coast. This storm was one of several that were documented during the first field phase of the Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE). In the 1–2 February case, soundings and wind profiler measurements showed that a wide cold-frontal rainband was coincident with the leading edge of an upper-level cold front in a classical warm occlusion. Ground-based radar observations revealed the presence of subbands within the wide cold-frontal rainband and two layers of precipitation generating cells within this rainband: one at 5–7 km MSL and the other at 9–10 km MSL. The lower layer of generating cells produced fallstreaks that were traced from the cells down to the radar bright band at 2 km MSL. Observations suggest a connection between the subbands and the lower layer of generating cells.

A research aircraft, equipped for cloud microphysical measurements, passed through at least two generating cells in the 5–7-km region. These cells were in their formative stage, with elevated liquid water contents and low ice particle concentrations.

The microphysical structure of the wide cold-frontal rainband was elucidated by particle imagery from a Cloud Particle Imaging (CPI) probe aboard the research aircraft. These images provide detailed information on crystal habits and degrees of riming throughout the depth of the rainband. The crystal habits are used to deduce the temperature and saturation conditions under which the crystals grew and, along with in situ measurements of particle size spectra, they are used to estimate particle terminal fall velocities, precipitation rates, radar reflectivities, and vertical air motions. The radar reflectivity derived in this way generally compared well with direct measurement. Both the derived and directly measured parameters are used to determine the primary particle growth processes in the wide cold-frontal rainband. Above the melting layer, vapor deposition was the dominant growth process in the rainband; growth of ice particles by riming was small. Significant aggregation of ice particles occurred in the region just above the melting layer. A doubling in the air-relative vertical precipitation mass flux occurred between the region where sheath ice crystals formed (−3° ≤ T ≤ −8°C) and the surface. Substantial amounts of liquid water were found within the melting layer where growth occurred by the accretion of cloud droplets and also by condensation. Growth by the collision and coalescence of raindrops was not significant below the melting layer.
Excitation of Transient Rossby Waves on the Stratospheric Polar Vortex and the Barotropic Sudden Warming
Authors: Esler J. G. , Scott R. K.
Published: October 2005

The excitation of Rossby waves on the edge of the stratospheric polar vortex, due to time-dependent topographic forcing, is studied analytically and numerically in a simple quasigeostrophic f-plane model. When the atmosphere is compressible, the linear response of the vortex is found to have two distinct components. The first is a spectrum of upward-propagating waves that are excited by forcing with temporal frequencies within a fixed “Charney–Drazin” range that depends on the angular velocity at the vortex edge and the vortex Burger number. The second component of the response is a barotropic mode, which is excited by forcing with a fixed temporal frequency outside the Charney–Drazin range. The relative magnitude of the two responses, in terms of total angular pseudomomentum, depends on the ratio of the horizontal scale of the forcing to the Rossby radius. Under typical stratospheric conditions the barotropic response is found to dominate. Nonlinear simulations confirm that the linear results remain relevant to understanding the response in cases when strongly nonlinear Rossby wave breaking ensues. It is shown that a sudden warming, or rapid increase in vortex angular pseudomomentum, can be generated at much lower forcing amplitudes when the barotropic mode is resonantly excited compared to when the upward-propagating waves are excited. A numerical simulation of a “barotropic sudden warming” due to excitation of the barotropic mode by a relatively weak topographic forcing is described.
The Structure and Maintenance of Stationary Waves in the Winter Northern Hemisphere
Authors: Chen Tsing-Chang
Published: October 2005

Previous studies of extratropical stationary waves in the winter Northern Hemisphere (NH) often focused on effects of orography and land–ocean thermal contrast on the formation, structure, and maintenance of these waves. In contrast, research attention to tropical stationary waves was attracted by the summer monsoon circulations and the ENSO-related climate variability. Consequently, the structure and basic dynamics of tropical stationary waves and the relationship of these waves with those in mid–high latitudes have long been neglected. Thus, the following several distinct features of observed winter NH stationary waves have not been explained: 1) an abrupt change in the longitudinal phase across 30°N; 2) a transition from the vertical phase reversal of tropical stationary waves to the vertically westward tilt of extratropical stationary waves; and 3) a longitudinally quarter-phase relationship between stationary waves and east–west circulations, and a reversal of this relationship across 30°N. It is inferred from a spectral streamfunction budget analysis with the NCEP–NCAR reanalyses that these wave features are caused by the transition of wave dynamics from the Sverdrup regime in the Tropics to the Rossby regime in the mid–high latitudes. Based on the simplified vorticity equations of these two dynamic regimes, analytic solutions obtained with observed velocity potential fields (which were used to portray the global divergent circulation) confirm that the aforementioned distinct features of stationary waves are attributed to the dynamics transition across 30°N. Since east–west circulations are part of the global divergent circulation, it is revealed from a diagnosis of the velocity potential maintenance equation that this circulation component is maintained in the Tropics primarily by diabatic heating and in the mid–high latitudes by both horizontal heat advection and diabatic heating. Evidently, stationary waves are maintained by diabatic heating through the divergent circulation and the dynamics transition of these waves from the Sverdrup regime to the Rossby regime is attributed to strong midlatitude westerlies.
The Response of Westerly Jets to Thermal Driving in a Primitive Equation Model
Authors: Son Seok-Woo , Lee Sukyoung
Published: October 2005

The structure of westerly jets in a statistically steady state is investigated with both dry and moist models on the sphere. The dry model is forced with an idealized radiative equilibrium temperature profile that consists of a global-scale base profile plus both localized tropical heating and high-latitude cooling. The tropical heating controls the intensity of the subtropical jet, while the high-latitude cooling modulates the meridional width of the extratropical baroclinic zone.

The jet structure is analyzed with a large number of dry model runs in which the tropical heating and high-latitude cooling rates are systematically varied. This parameter study shows that, in a regime with weak tropical heating and strong high-latitude cooling, the polar-front jet separates itself from the subtropical jet, forming a double-jet state. In contrast, if the tropical heating rate is greater than a certain value, a strong single jet emerges, indicating that the presence of one or two jets in a statistically steady state is dependent upon the relative values of both the tropical heating and the baroclinic zone width.

A set of moist model runs is examined in which the moisture content is systematically varied. For a relatively small moisture content, the circulation prefers a double-jet state. However, for a moisture content that is greater than a certain threshold value, the two jets collapse into a single jet. With the aid of the aforementioned dry model results, an explanation for this nonlinear response exhibited by the moist model is provided. Based on the results of the dry and moist model calculations, this paper discusses various physical interpretations of the circulation responses to global warming presented in the literature.
A Comparison of Grid Quality of Optimized Spherical Hexagonal–Pentagonal Geodesic Grids
Authors: Miura Hiroaki , Kimoto Masahide
Published: October 2005

Construction and optimization methods of spherical hexagonal–pentagonal geodesic grids are investigated. The objective is to compare grid structures on common ground.

The distinction between two types of hexagonal–pentagonal grids is made. Three conventional grid optimization methods are summarized. In addition, three new optimization methods are proposed. Six desirable conditions for an ideal grid are described, and the grid optimization methods are organized in view of such conditions.

Interval uniformity, area uniformity, isotropy, and bisection of cell faces are systematically investigated for optimized grids. There are compensations of preferable grid features in each optimization method, and an optimal method cannot be decided based only on the research of grid features. It is suggested that grid optimization methods should be selected based on research of numerical schemes.
Quantitative Precipitation Forecasting of Wintertime Storms in the Sierra Nevada: Sensitivity to the Microphysical Parameterization and Horizontal Resolution
Authors: Grubišić Vanda , Vellore Ramesh K. , Huggins Arlen W.
Published: October 2005

The skill of a mesoscale model in predicting orographic precipitation during high-impact precipitation events in the Sierra Nevada, and the sensitivity of that skill to the choice of the microphysical parameterization and horizontal resolution, are examined. The fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) and four bulk microphysical parameterization schemes examined are the Dudhia ice scheme, and the Schultz, GSFC, and Reisner2 mixed-phase schemes. The verification dataset consists of ground precipitation measurements from a selected number of wintertime heavy precipitation events documented during the Sierra Cooperative Pilot Project in the 1980s. At high horizontal resolutions, the predicted spatial precipitation patterns on the upwind Sierra Nevada slopes were found to have filamentary structure, with precipitation amounts over the transverse upwind ridges exceeding severalfold those over the nearby deep river valleys. The verification results show that all four tested bulk microphysical schemes in MM5 produce overprediction of precipitation on both the windward and lee slopes of the Sierra Nevada. The examined accuracy measures indicate that the Reisner2 scheme displays the best overall performance on both sides of the mountain range. The examined statistical skill scores on the other hand reveal that, regardless of the microphysical scheme used, the skill of the MM5 model in predicting the observed spatial distribution of the Sierra Nevada orographic precipitation is fairly low, that this skill is not improved by increasing the horizontal resolution of the model simulations, and that on average the quantitative precipitation forecasting (QPF) skill is better on the windward than on the lee side. Furthermore, a significance test shows that differences in skill scores obtained with the four microphysical schemes are not statistically significant.
Evaluation of a Linear Phase Observation Operator with CHAMP Radio Occultation Data and High-Resolution Regional Analysis
Authors: Sokolovskiy S. , Kuo Y-H. , Wang W.
Published: October 2005

In this study a nonlocal, linear observation operator for assimilating radio occultation data is evaluated. The operator consists of modeling the excess phase, that is, integrating the refractivity along straight lines tangent to rays, below a certain height. The corresponding observable is the excess phase integrated through the Abel-retrieved refractivity, along the same lines, below the same height. The operator allows very simple implementation (computationally efficient) while accurately accounting for the horizontal refractivity gradients. This is due to significant cancellation of the linearization and discretization errors when modeling the observable. Evaluation of the operator with Challenging Minisatellite Payload (CHAMP) radio occultation data and grid refractivity fields from high-resolution regional analysis over the continental United States showed reduction of the observation error in the troposphere (below 7 km) 1.5–2 times, compared to the error of local refractivity. The operator is useful for the assimilation of radio occultation data by high-resolution weather models in the troposphere.
Sensitivity of North American Monsoon Rainfall to Multisource Sea Surface Temperatures in MM5
Authors: Li J. , Gao X. , Maddox R. A. , Sorooshian S.
Published: October 2005

In this article, four continually processed sea surface temperature (SST) datasets, including the Reynolds SST (RYD), the global final analysis of skin temperature at oceans (FNL), and two Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua SSTs retrieved from thermal infrared imagery (TIR) and midinfrared imagery (MIR), were compared. The results show variations from each other. In comparison with the RYD SST, the FNL data have −0.5° ∼ 0.5°C perturbations, while the TIR and MIR SSTs possess larger deviations of −2° ∼ 1°C, mainly due to algorithm and/or sensor differences in these SST datasets.

A regional model, the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (Penn State–NCAR) Mesoscale Model (MM5), was used to investigate whether model atmospheric predictions, especially those concerning precipitation during the North American monsoon season, are sensitive to these SST variations. A comparison of rainfall, atmospheric height, temperature, and wind fields produced by model results, reanalysis data, and observations indicates that, at monthly scale, the model shows changes in the simulations for three consecutive years; in particular, rainfall amounts, timing, and even patterns vary at some specific regions. Forced by the MODIS Aqua midinfrared SST (MIR), which includes large regions with SST values lower than the conventional Reynolds SST, the MM5 rain field predictions show reduced errors over land and oceans compared to when the model is forced by other SST data. Specifically, rainfall estimates are improved over the offshore of southern Mexico, the Gulf of Mexico, the coastal regions of southern and eastern Mexico, and the southwestern U.S. monsoon active region, but only slightly improved over the monsoon core and the high-elevated Great Plains. Using MIR SST data, one is also capable of improving geopotential height and temperature fields in comparison with the reanalysis data.
Impact of El Niño/La Niña on the Seasonality of Oceanic Water Vapor: A Proposed Scheme for Determining the ITCZ
Authors: Chen Ge , Lin Hui
Published: October 2005

Previous research has shown that oceanic water vapor (OWV) is a useful quantity for studying the low-frequency variability of the atmosphere–ocean system. In this work, 10 years (1993–2002) of high-quality OWV data derived from the Ocean Topography Experiment (TOPEX) microwave radiometer are used to investigate the impact of El Niño/La Niña on the amplitude and phase of the annual cycle. These results suggest that El Niños (La Niñas) can weaken (strengthen) the seasonality of OWV by decreasing (increasing) the annual amplitude. The change of amplitude is usually slight but significant, especially for the five most dynamic seasonal belts across the major continents at midlatitudes. The El Niño–Southern Oscillation (ENSO) impact on the annual phase of OWV is seen to be fairly systematic and geographically correlated. The most striking feature is a large-scale advancing/delay of about 10 days (as estimated through empirical modeling) for the midlatitude oceans of the Northern Hemisphere in reaching their summer maxima during the El Niño/La Niña years. In addition, an alternative scheme for estimating the mean position of the intertropical convergence zone (ITCZ) based on the annual phase map of OWV is proposed. This ITCZ climatology favors 4°N in mean latitude, and agrees with existing results in that its position meanders from 2°S to 8°N oceanwide, and stays constantly north of the equator over the Atlantic and eastern Pacific.
Atmospheric Hydrology of the Anomalous 2002 Indian Summer Monsoon
Authors: Fasullo J.
Published: October 2005

The 2002 Indian summer monsoon season is unique because of its exceptional weakness, its association with a relatively weak El Niño, and its precedence by over a decade in which ENSO events fail to be associated with significant monsoon anomalies. In this study, atmospheric hydrology during the 2002 summer monsoon and its relationship to monsoon seasons accompanying El Niño events since 1948 are assessed using reanalysis and satellite fields.

Strong hydrologic deficits are identified for July and September 2002. During July, the impact of the disturbed Hadley and Walker circulations in the African and Indian Ocean region on vertically integrated moisture transport (VIMT) in the Arabian Sea and India is found to be key to the Indian drought. Interhemispheric coherence in satellite-derived surface wind anomalies is also identified. During September, VIMT and surface wind anomalies, both to the east and west of India, contribute to anomalous moisture divergence in India. Bay of Bengal SST and Indian CAPE anomalies are found to act in response to the season’s major break episodes, contrary to other studies that suggest their role as instigators of break periods.

The 2002 season is also found to exhibit characteristics that are common to other recent weak monsoons accompanying El Niño, such as strong westerly VIMT anomalies in the western Pacific Ocean and easterly VIMT anomalies in the Arabian Sea. Hydrologic anomalies that distinguish many recent normal monsoon seasons coinciding with El Niño from the El Niño distribution overall are not evident in 2002. In many respects, the 2002 season thus represents a reemergence of the hydrologic anomalies that have accompanied a strong monsoon–ENSO teleconnection over the past 50 yr and may present a challenge for perspectives that suggest a lasting decoupling of the monsoon–ENSO systems.
Retrospective Forecasts of Interannual Sea Surface Temperature Anomalies from 1982 to Present Using a Directly Coupled Atmosphere–Ocean General Circulation Model
Authors: DeWitt David G.
Published: October 2005

A large number of ensemble hindcasts (or retrospective forecasts) of tropical Pacific sea surface temperature (SST) have been made with a coupled atmosphere–ocean general circulation model (CGCM) that does not employ flux correction in order to evaluate the potential skill of the model as a seasonal forecasting tool. Oceanic initial conditions are provided by an ocean data assimilation system. Ensembles of seven forecasts of 6-month length are made starting each month in the 1982 to 2002 period. Skill of the coupled model is evaluated from both a deterministic and a probabilistic perspective. The skill metrics are calculated using both the bulk method, which includes all initial condition months together, and as a function of initial condition month. The latter method allows a more objective evaluation of how the model has performed in the context in which forecasts are actually made and applied. The deterministic metrics used are the anomaly correlation and the root-mean-square error. The coupled model deterministic skill metrics are compared with those from persistence and damped persistence reference forecasts. Despite the fact that the coupled model has a large cold bias in the central and eastern equatorial Pacific this coupled model is shown to have forecast skill that is competitive with other state-of-the-art forecasting techniques.

Potential skill from probabilistic forecasts made using the coupled model ensemble members are evaluated using the relative operating characteristics method. This analysis indicates that for most initial condition months this coupled model has more skill at forecasting cold events than warm or neutral events in the central Pacific.

In common with other forecasting systems, the coupled model forecast skill is found to be lowest for forecasts passing through the Northern Hemisphere (NH) spring. Diagnostics of this so-called spring predictability barrier in the context of this coupled model indicate that two factors likely contribute to this predictability barrier. First, the coupled model shows a too-weak coupling of the surface and subsurface temperature anomalies during NH spring. Second, the coupled-model-simulated signal-to-noise ratio for SST anomalies is much lower during NH spring than at other times of the year, indicating that the model’s potential predictability is low at this time.
Using Sounding Data to Detect Gulf Surges during the North American Monsoon
Authors: Dixon P. Grady
Published: October 2005

Periodic surges of moisture from the Gulf of California are considered to be partly responsible for widespread showers and thunderstorms across the deserts of Arizona during the summer monsoon season. Presently, the primary method for detecting these surges is to look for changes in the surface observations at Yuma, Arizona. Unfortunately, these surface data are easily influenced by gust fronts, marine layers, and the dramatic diurnal patterns of the desert environment. Therefore, a new method for Assessing Low-level Atmospheric Moisture using Soundings (ALARMS) is proposed. Gulf surge–induced moisture increases identified by this new set of criteria are compared to other methods in order to determine the usefulness of each. This study demonstrates that the proposed method performs much better than the others that were tested, with the additional advantage of being relatively easy to apply.
Development of Convective Systems over Baja California during Tropical Cyclone Linda (2003)
Authors: Farfán Luis M.
Published: October 2005

Characteristics of the life cycle and motion of convective systems that occurred over the Baja California Peninsula were determined from a case study in September of 2003. This note applies data from satellite imagery, regular observations from upper-air and surface networks, and operational analyses. Changes in environmental conditions over northwestern Mexico are documented and these are associated with the development of Tropical Cyclone Linda in the eastern Pacific Ocean. When Linda became a tropical storm and was located several hundred kilometers away to the southwest, a convective outbreak occurred over land.

An examination of large-scale conditions indicated that flow from the eastern flank of Linda supplied low- to midlevel moisture. Significant convection is associated with specific thresholds for precipitable water, CAPE, and lifted index. Convective systems initiated in the early afternoon remained active for several hours and provided localized areas of precipitation along the western side of the peninsular mountains. An assessment of all the available surface data was performed to determine regional elements that played a role in the development of these systems. Results include documentation of a sea breeze from the Gulf of California onto the mountain slopes when organized convection was first detected.
The Improved AMSU Rain-Rate Algorithm and Its Evaluation for a Cool Season Event in the Western United States
Authors: Qiu Shuang , Pellegrino Paul , Ferraro Ralph , Zhao Limin
Published: October 2005

Rain-rate retrievals from passive microwave sensors are useful for a number of applications related to weather forecasting. For example, in the United States, such estimates are useful for offshore rainfall systems approaching land and in regions where the Weather Surveillance Radar-1988 Doppler (WSR-88D) network is inadequate. Improvements have been made to the rain-rate retrieval from the Advanced Microwave Sounding Unit (AMSU) on board the National Oceanic and Atmospheric Administration (NOAA) Polar Orbiting Environmental Satellites (POESs). The new features of the improved rain-rate algorithm include a two-stream correction of the satellite brightness temperatures at 89 and 150 GHz, cloud- and rain-type classification for better retrieval of rain rate, and removal of the two ad hoc thresholds in the ice water path (IWP) and effective diameter (De) retrieval where the scattering signals are very small. In this paper, the new algorithm has been compared to the previous NOAA operational algorithm. In particular, the better utilization of the measurements at and above 150 GHz is shown to produce improved sensitivity to light rainfall associated with winter season storm systems. This improvement is demonstrated through a wintertime case study over southern California during February 2003.
The 4 June 1999 Derecho Event: A Particularly Difficult Challenge for Numerical Weather Prediction
Authors: Gallus William A. , Correia James , Jankov Isidora
Published: October 2005

Warm season convective system rainfall forecasts remain a particularly difficult forecast challenge. For these events, it is possible that ensemble forecasts would provide helpful information unavailable in a single deterministic forecast. In this study, an intense derecho event accompanied by a well-organized band of heavy rainfall is used to show that for some situations, the predictability of rainfall even within a 12–24-h period is so low that a wide range of simulations using different models, different physical parameterizations, and different initial conditions all fail to provide even a small signal that the event will occur. The failure of a wide range of models and parameterizations to depict the event might suggest inadequate representation of the initial conditions. However, a range of different initial conditions also failed to lead to a well-simulated event, suggesting that some events are unlikely to be predictable with the current observational network, and ensemble guidance for such cases may provide limited additional information useful to a forecaster.
The internet's political impact and the penetration/participation paradox in Malaysia and Singapore
Authors: George Cherian
Published: October 2005

How intensively a communication technology is used depends on factors other than its level of diffusion. Accordingly, a country with lower penetration levels for a medium may, paradoxically, exhibit more and better utilization of that medium than a country with higher penetration. This penetration/participation paradox is seen in the case of Malaysia and Singapore. Singapore is significantly ahead in terms of network availability, but it is Malaysia that has the more developed political activism online. The paradox cannot be explained by the two countries’ regulatory regimes, which are more similar than different. Instead, the differences can be accounted for by traditional social networks that help to organize online dissent, and the motivation to use available technology in creatively political ways - both of which are stronger in Malaysia than in Singapore. This case study highlights the importance of social and political context in the shaping the impact of new communication technologies.
Cross-Validation of the Self-Appraisal Questionnaire: A Tool for Assessing Violent and Nonviolent Recidivism With Female Offenders
Authors: Loza Wagdy , Neo Lee Hong , Shahinfar Ariana , Loza-Fanous Amel
Published: October 2005

The Self-Appraisal Questionnaire (SAQ) is a 72-item self-report measure designed to predict violent and nonviolent recidivism among adult male criminal offenders. It was administered to 91 female offenders incarcerated in Pennsylvania and 183 incarcerated in Singapore correctional systems. Results indicated that the SAQ has sound psychometric properties, with acceptable reliability and concurrent and predictive validity for assessing violent and nonviolent recidivism. There were no significant differences between the scores of African American and Asian offenders and the responses of the White offenders. Similar to the findings from male offenders, the present results provide some support for the validity of the SAQ in the prediction of violent and nonviolent recidivism risk among White, African American, and Asian female offenders.
Simple schizophrenia or disorganisation syndrome? A case report and review of the literature
Authors: Whitwell Susannah , Bramham Jessica , Moriarty John
Published: October 2005

Simple schizophrenia is a sometimes controversial diagnosis. Here we review the concept with particular reference to its history in diagnostic systems. Using an illustrative real case of a 25-year-old man, we show that there is a need to retain this diagnostic category, which may fit better within proposed dimensional (psychomotor poverty, disorganisation and reality distortion) rather than categorical classifications of schizophrenia. Symptoms of the disorder may be better revealed by functional assessment than by relying on descriptive psychopathology.
Neuropsychiatric effects of caffeine
Authors: Winston Anthony P. , Hardwick Elizabeth , Jaberi Neema
Published: October 2005

Psychiatrists rarely enquire about caffeine intake when assessing patients. This may lead to a failure to identify caffeine-related problems and offer appropriate interventions. Excessive caffeine ingestion leads to symptoms that overlap with those of many psychiatric disorders. Caffeine is implicated in the exacerbation of anxiety and sleep disorders, and people with eating disorders often misuse it. It antagonises adenosine receptors, which may potentiate dopaminergic activity and exacerbate psychosis. In psychiatric in-patients, caffeine has been found to increase anxiety, hostility and psychotic symptoms. Assessment of caffeine intake should form part of routine psychiatric assessment and should be carried out before prescribing hypnotics. Gradual reduction in intake or gradual substitution with caffeine-free alternatives is probably preferable to abrupt cessation. Decaffeinated beverages should be provided on psychiatric wards.
Structural brain correlates of unconstrained motor activity in people with schizophrenia
Authors: Farrow Tom F. D. , Hunter Michael D. , Wilkinson Iain D. , Green Russell D. J. , Spence Sean A.
Published: October 2005

Avolition affects quality of life in chronic schizophrenia. We investigated the relationship between unconstrained motor activity and the volume of key executive brain regions in 16 male patients with schizophrenia. Wrist-worn actigraphy monitors were used to record motor activity over a 20 h period. Structural magnetic resonance imaging brain scans were parcellated and individual volumes for anterior cingulate cortex and dorsolateral prefrontal cortex extracted. Patients' total activity was positively correlated with volume of left anterior cingulate cortex. These data suggest that the volume of specific executive structures may affect (quantifiable) motor behaviours, having further implications for models of the ‘will’ and avolition.
Impact of a fast-track assessment clinic on waiting times and non-attendance rates for new referrals to a community mental health centre
Authors: Ogunbamise Akinwande , Reardon Marion , Mohoboob Mo , Lelliott Paul
Published: October 2005

Aims and Method

A new fast-track assessment (FTA) clinic was established by a community mental health team (CHMT) in SouthEast London. Previously, those who responded to an opt-in letter were offered an appointment with a duty worker or at an out-patient clinic. In the new system, all routine referrals are booked into a single fortnightly clinic staffed by two doctors and two to three other CMHT staff with post-clinic discussion of all cases (2–6 min per case). A total of 100 consecutive referrals before the introduction of the FTA clinic were compared with 100 following the introduction.

Results

The interval between receipt of referral to first appointment offered was reduced from 55 to 18 days and to actual assessment from 71 to 26 days. Eighty-four referrals to the FTA were offered a first appointment date that was within 21 days of receipt of a referral, compared with four before the introduction of the FTA. These differences were highly significant. There was a trend for more patients to attend for assessment after the FTA clinic was introduced (79 compared with 68).

Clinical Implications

This simple re-engineering of the assessment process within a CMHT has achieved its objective of reducing waiting times to first assessment appointment. It also appears to have reduced the number of referrals that do not result in an assessment.
Service innovations
Authors: Hayward Mark , West Steve , Green Moira , Blank Alison
Published: October 2005

Health policy guidelines state that people who use mental health services should be involved in the development of the services they receive (Department of Health, 1999). Examples of good practice in this respect are reported from staff recruitment (Diamond et al, 2003), research (Trivedi & Wykes, 2002) and training (Repper, 2000; Harper, 2003). However, support for user involvement is not universal (Summers, 2003; Soffe, 2004) and, most significantly, there is considerable confusion about what is meant by involvement. The following case study will address these issues by: (a) adding to the evidence regarding the successful involvement of service users in training; and (b) clarifying the process by which involvement can be safely achieved.