bluuebunny/crossref_metadata_2025 huggingface dataset:
First-principles study of phosphorus diffusion in silicon: Interstitial- and vacancy-mediated diffusion mechanisms
Authors: Liu Xiang-Yang , Windl Wolfgang , Beardmore Keith M. , Masquelier Michael P.
Published: March 2003

A vacancy-mediated diffusion mechanism has been assumed in traditional models of P diffusion in Si. However, recent experiments have suggested that for intrinsic P diffusion in Si, the interstitial-assisted diffusion mechanism dominates. Here, we describe first-principles calculations of P diffusion in Si performed to study interstitial- and vacancy-mediated diffusion mechanisms. Special care is taken with regard to structural minimization, charge state effects and corrections. We calculated the defect formation energies and migration barriers for the various competing P–interstitial diffusion mechanisms, as well as P–vacancy diffusion energetics in different charge states. For P–interstitial diffusion, we find overall diffusion activation energies of 3.1–3.5 eV for neutral and +1 charge states, in close agreement with experiments at intrinsic conditions. For P–vacancy diffusion, our calculation is in agreement with previous calculations in the neutral case, but suggests that only P+V= plays a role in the heavily doped n region while the interstitial mechanisms may dominate in near-intrinsic regions.
Temperature oscillations produced by an impulsive interfacial line heat source
Authors: Shendeleva Margarita L.
Published: March 2003

Transient thermal waves generated by an instantaneous line heat source located at the boundary between two semi-infinite heat-conductive media are studied using the temperature Green functions derived previously by the Cagniard–de Hoop method. A simple analytical formula is obtained for the temperature field at the interface. With this formula, the change of sign of the reflected temperature field along the interface is analyzed, and the relationship between the zero point of the reflected field and the thermal parameters of the two media is derived. The solutions for interfacial fields can be useful for the determination of thermal properties of two media in thermal contact and for nondestructive evaluation with thermal waves.
Nitrogen-enhanced negative bias temperature instability: An insight by experiment and first-principle calculations
Authors: Tan Shyue Seng , Chen T. P. , Soon Jia Mei , Loh Kian Ping , Ang C. H. , Chan L.
Published: March 2003

The nitrogen-enhanced negative bias temperature instability (NBTI) effect has been studied experimentally and theoretically. It is observed that both the interface state and positive fixed charge generation increase linearly with interfacial nitrogen concentration. The experimental results can be understood in terms of the reaction energies of the hydrogen trapping reactions at the interface, which are obtained from first-principle calculations. These results improve our understanding of the mechanisms responsible for the nitrogen-enhanced NBTI effect.
Superheating systematics of crystalline solids
Authors: Luo Sheng-Nian , Ahrens Thomas J.
Published: March 2003

Systematics of superheating (θ=T/Tm−1) of crystalline solids as a function of heating rate (Q) are established as β=A(Q)(θ+1)θ2, where the normalized energy barrier for homogeneous nucleation is β=16πγsl3/(3kTmΔHm2), T is temperature, Tm melting temperature, A a Q-dependent parameter, γsl interfacial energy, ΔHm heat of fusion, and k Boltzmann’s constant. For all elements and compounds investigated, β varies between 0.2 and 8.2. At 1 and 1012 K/s, A=60 and 31, θ=0.05–0.35 and 0.06–0.45, respectively. Significant superheating is achievable via ultrafast heating. We demonstrate that the degree of superheating achieved in shock-wave loading and intense laser irradiation as well as in molecular dynamics simulations (Q∼1012 K/s) agrees with the θ–β–Q systematics.
Room-temperature grain growth in sputter-deposited Cu films
Authors: Detavernier C. , Deduytsche D. , Van Meirhaeghe R. L. , De Baerdemaeker J. , Dauwe C.
Published: March 2003

The microstructure of sputter-deposited Cu films is shown to be unstable at room temperature (RT). The average grain size increases significantly during RT storage for a couple of hours after deposition. This RT grain growth is shown to be very dependent on the deposition parameters (substrate temperature and sputter gas pressure) and hence on the microstructure of the as-deposited film. The microstructure of sputter-deposited films is usually summarized in a structure-growth-zone model. It is found that significant RT grain growth only occurs for Cu layers with a zone-T-type, as-deposited microstructure.
Epitaxial L10 FePt magnetic thin films sputtered on Cu (001)
Authors: Sun C. J. , Chow G. M. , Wang J. P.
Published: March 2003

Epitaxial Fe50Pt50 (30 nm) magnetic thin films were sputter-deposited on Cu (001) single crystal substrate. The fct L10 ordered FePt (200)〈001〉∥Cu (002)〈100〉 epitaxial relationship was observed using high-resolution x-ray scattering. The L10 ordered FePt film sputtered at 400 °C with well-controlled easy-axis distribution (full width at half-maximum=2.36°), small grain size (10 nm), and high in-plane coercivity (4.4 kOe) is a potential candidate for ultrahigh-density longitudinal magnetic recording media.
Ultralow copper drift in inductively coupled plasma silicon carbide dielectrics
Authors: Shieh Jia-Min , Tsai Kou-Chiang , Dai Bau-Tong
Published: March 2003

This study investigates how copper penetration into inductively coupled plasma (ICP) trimethylsilane-based hydrogenated amorphous silicon carbide (a-SiCx:H) dielectric barriers depends on the films’ hydrogen concentrations. Depositing ICP a-SiCx:H films with low hydrogen concentrations (or few defect sites), copper drift rate in such films stressed at around 200 °C, 1 MV/cm, is as low as 105 ions/cm2 s, two to five times lower than those in plasma-enhanced chemical-vapor-deposited (PECVD) a-SiCx:H and nitride barriers. Accordingly, the time-to-breakdown of ICP a-SiCx:H subjected to bias-temperature stress at above 200 °C, 2.0–2.75 MV/cm, is almost one order of magnitude longer than that of PECVD a-SiCx:H.
Repeatable hydrogen adsorption using nanostructured graphite at room temperature
Authors: Kajiura H. , Kadono K. , Tsutsui S. , Murakami Y.
Published: March 2003

Repeatable hydrogen adsorption and desorption by nanostructured graphite was confirmed using a high-accuracy volumetric measuring apparatus at room temperature. The nanostructured graphite was prepared from graphite powder using a mechanical milling process at a pressure of 2.0×10−4 Pa. The untreated graphite adsorbed 0.02 wt % of hydrogen, while 0.20–0.25 wt % of hydrogen can be repeatedly adsorbed by the nanostructured graphite. Measurements of the hydrogen adsorption rate at constant pressure and pore-size distribution suggest that the hydrogen molecules are adsorbed through a diffusion process into pores with a diameter less than 1 nm.
Current mapping of GaN films by conductive atomic force microscopy
Authors: Pomarico A. A. , Huang D. , Dickinson J. , Baski A. A. , Cingolani R. , Morkoç H. , Molnar R.
Published: March 2003

Conductive atomic force microscopy has been used to investigate the local conductivity in hydride vapor-phase epitaxy and molecular-beam epitaxy GaN films, focusing on the effect of off-axis facet planes. We investigated two different types of samples, in which the facet planes were either present on the perimeters of as-grown islands, or on the edges of etch pits created by post-growth chemical etching. The results show that crystallographic planes tilted with respect to the c-plane growth direction show a significantly higher conductivity than surrounding areas. The n-type (or p-type) samples required a negative (or positive) sample bias for current conduction, consistent with the formation of a Schottky barrier between the metallized atomic force microscope tip and sample. The time dependence of this enhanced conductivity was different for the two types of samples, possibly indicating different conduction mechanisms.
Ultrafast directional nickel-silicide-induced crystallization of amorphous silicon under high-density current stressing
Authors: Yu C. H. , Lin H. H. , Cheng S. L. , Chen L. J.
Published: March 2003

Ultrafast directional crystallization that combined the electric current stressing with metal-induced crystallization has been achieved for BF2+-implanted amorphous Si (a-Si) at room temperature. Polycrystalline Si was observed to grow from anode towards cathode and the channels of a-Si strips with a length of 140 μm and a width of 10 μm can be fully crystallized with a stressing time less than 0.2 s. The directional growth of crystalline Si nanowires, 50 nm in width and as long as 3 μm in length, with an extraordinarily high aspect ratio of 60, indicates a strong electric-field-induced effect on the growth. The growth method provides a promising scheme to solve the problems caused by high-temperature and long-term annealing treatment for the applications of optoelectronic devices.
Nonlinear positive temperature coefficient of resistance of BaTiO3 film
Authors: Okano Motochika , Watanabe Yukio , Cheong Sang-Wook
Published: March 2003

Conductance decreasing with increasing temperature (T) above a characteristic T (T0) is found in the reverse-diode characteristics of metal contacts on strained BaTiO3 epitaxial films. The conduction mechanisms below and above T0 near the Curie temperature of the bulk BaTiO3 are distinctly different. Marked similarities to these characteristics are found in the surface conduction on BaTiO3 single crystal in a high vacuum. By comparing the observations with the positive temperature coefficient of resistance (PTCR) effect in ceramics, we suggest that the anomaly is regarded as a PTCR effect at metal/ferroelectric contact, and discuss the origin of the effect in thin films and single crystals.
GaInNAs/GaAs quantum wells grown by molecular-beam epitaxy emitting above 1.5 μm
Authors: Tournié E. , Pinault M.-A. , Laügt M. , Chauveau J.-M. , Trampert A. , Ploog K. H.
Published: March 2003

We demonstrate that a careful optimization of the molecular-beam-epitaxy growth conditions allows us to obtain high-quality GaInNAs/GaAs quantum-well (QW) heterostructures exhibiting a perfect two-dimensional microstructure at high In and N contents. Room-temperature emission is achieved up to 1.61 and 1.51 μm for as-grown and annealed samples, respectively. High-resolution x-ray diffraction and transmission electron microscopy reveal that post-growth annealing does not affect the QW composition and width. This confirms that the GaInNAs semiconducting material is well suited for emission in the telecommunication wavelength range near 1.55 μm.
Enhanced photoluminescence from CdS:Mn/ZnS core/shell quantum dots
Authors: Yang Heesun , Holloway Paul H.
Published: March 2003

Enhanced photoluminescence (PL) is reported from Mn2+-doped CdS nanocrystals capped with ZnS (CdS:Mn/ZnS core/shell) that were prepared using a reverse micelle route. Compared to organically (n-dodecanethiol) capped CdS:Mn nanocrystals, CdS:Mn/ZnS core/shell nanocrystals exhibited much stronger and sharper Mn2+ 4T1–6A1 yellow PL emission. This is presumably the result of effective passivation of CdS surface states by the ZnS shell and consequent suppression of nonradiative recombination transitions. The core/shell nanostructure was confirmed using x-ray photoelectron spectroscopy and energy dispersive spectroscopy data.
MoS
2
nanoflowers and their field-emission properties
Authors: Li Y. B. , Bando Y. , Golberg D.
Published: March 2003

Elegant three-dimensional MoS2 nanoflowers were uniformly formed via heating a MoO2 thin film in a vapor sulfur atmosphere. Tens to hundreds of petals were self-assembled within a single nanoflower. Each petal, 100–300 nm wide and only several nanometers thick, exhibited a hexagonal structure. The number of petal layers gradually decreased towards the edges, resulting in uniquely thin edges, typically less than 3 nm. The MoS2 nanoflowers appeared to be excellent field emitters displaying a current density of 0.01 and 10 mA/cm2 at macroscopic fields of 4.5–5.5 and 7.6–8.6 V/μm, respectively; the electron field emission was consistent with the Fowler–Nordheim theory.
High-resolution potential mapping in semiconductor nanostructures by cross-sectional scanning tunneling microscopy and spectroscopy
Authors: Modesti S. , Furlanetto D. , Piccin M. , Rubini S. , Franciosi A.
Published: March 2003

Using a combination of scanning tunneling microscopy and spectroscopy techniques, and a series of periodic δ-doped structures in GaAs, we show that the electrostatic potential can be mapped along {110} cross sections in semiconductor nanostructures with nanometer resolution and 30 meV sensitivity. Our results also indicate that microscopic capacitors with plates spaced by as little as 2 nm can be implemented by δ doping for band gap engineering purposes.
Pronounced switching bistability in a feedback coupled nanoelectronic Y-branch switch
Authors: Reitzenstein S. , Worschech L. , Hartmann P. , Forchel A.
Published: March 2003

Electron Y-branch switches (YBSs) were fabricated in modulation-doped GaAs/AlGaAs heterostructures by electron-beam lithography and etching techniques. The YBS is controlled by two lateral sidegates. Feedback coupling of one of the branches to the adjacent sidegate leads to a pronounced switching bistability when varying the voltage at the other sidegate. This mode of operation is associated with a Schmitt–Trigger-like switching hysteresis of up to 135 mV.
Gallium-mediated growth of multiwall carbon nanotubes
Authors: Pan Zheng Wei , Dai Sheng , Beach David B. , Evans Neal D. , Lowndes Douglas H.
Published: March 2003

Liquid gallium was used as a viable and effective solvent and template for high-yield growth of multiwall carbon nanotubes. The gallium-mediated nanotubes thus obtained differ morphologically from nanotubes obtained by using transition metals as catalysts. The nanotubes have a pin-like morphology, generally composed of an oval-shaped tip filled with liquid gallium and a tapered hollow body. The inner diameter of the tube is so large that the inner/outer diameter ratio is usually larger than 0.9. The tubes are naturally opened at both ends. These gallium-filled nanotubes may be used as a nanothermometer in the temperature range of 30 to 550 °C. This study opens an interesting route for carbon nanotube synthesis.
Flexible pulse-wave sensors from oriented aluminum nitride nanocolumns
Authors: Akiyama Morito , Ueno Naohiro , Nonaka Kazuhiro , Tateyama Hiroshi
Published: March 2003

Flexible pulse-wave sensors were fabricated from density-packed oriented aluminum nitride nanocolumns prepared on aluminum foils. The nanocolumns were prepared by the rf magnetron sputtering method and were perpendicularly oriented to the aluminum foil surfaces. The sensor structure is laminated, and the structure contributes to avoiding unexpected leakage of an electric charge. The resulting sensor thickness is 50 μm. The sensor is flexible like aluminum foil and can respond to frequencies from 0.1 to over 100 Hz. The sensitivity of the sensor to pressure is proportional to the surface area. The sensor sensitively causes reversible charge signals that correlate with the pulse wave form, which contains significant information on arteriosclerosis and cardiopathy of a man sitting on it.
Observation of optical phonon instability induced by drifting electrons in semiconductor nanostructures
Authors: Liang W. , Tsen K. T. , Sankey Otto F. , Komirenko S. M. , Kim K. W. , Kochelap V. A. , Wu Meng-Chyi , Ho Chong-Long , Ho Wen-Jeng , Morkoç H.
Published: March 2003

We have experimentally proven the Cerenkov generation of optical phonons by drifting electrons in a semiconductor. We observe an instability of the polar optical phonons in nanoscale semiconductors that occurs when electrons are accelerated to very high velocities by intense electric fields. The instability is observed when the electron drift velocity is larger than the phase velocity of optical phonons and rather resembles a “sonic boom” for optical phonons. The effect is demonstrated in p–i–n semiconductor nanostructures by using subpicosecond Raman spectroscopy.
Fabrication of coupled quantum dots for multiport access
Authors: Holleitner Alexander W. , Blick Robert H. , Eberl Karl
Published: March 2003

We introduce a versatile two-step electron-beam fabrication technique for defining multiport quantum dots in GaAs/AlGaAs heterostructures in close vicinity. Capacitive coupling of the two quantum dots is directly tuned electrostatically via two central gates. Parallel access is realized by patterning source and drain contact regions of both dots with an additional spacer layer. Conductance measurements give evidence of both the continuous wide-range tunability of the dots and parallel access to the circuit.
Origin of metal–insulator transition temperature enhancement in underdoped lanthanum manganite films
Authors: Murugavel P. , Lee J. H. , Yoon Jong-Gul , Noh T. W. , Chung J.-S. , Heu M. , Yoon S.
Published: March 2003

The possibility of controlling transport properties of colossal magnetoresistance manganite films using substrate-induced strain has attracted great interest. We have investigated transport properties of La0.9Ca0.1MnO3, La0.92Ba0.08MnO3, La0.8Ba0.2MnO3, and LaMnO3 films. When the films were post-annealed at proper conditions, all of them showed metal–insulator transitions. Their transition temperatures TMI were much higher than the corresponding bulk values, irrespective of the type of substrate-induced biaxial strain. This surprising fact demonstrated that strain could not be the main origin of the TMI enhancement observed in the underdoped (dopant concentration x<0.3) manganite films. We suggested that TMI enhancements should be attributed mostly to the cationic vacancies in the post-annealed films.
Simultaneous two-state lasing in quantum-dot lasers
Authors: Markus A. , Chen J. X. , Paranthoën C. , Fiore A. , Platz C. , Gauthier-Lafaye O.
Published: March 2003

We demonstrate simultaneous lasing at two well-separated wavelengths in self-assembled InAs quantum-dot lasers, via ground-state (GS) and excited-state (ES) transitions. This effect is reproducible and strongly depends on the cavity length. By a master-equation model, we attribute it to incomplete clamping of the ES population at the GS threshold.
Perceptual Organization and White's Illusion
Authors: Anderson Barton L
Published: March 2003

The apparent lightness of a surface can be strongly modulated by the spatial context in which it is embedded. Early theories of such context dependence emphasized the role of low-level mechanisms that sense border contrast, whereas a number of recent authors have emphasized the role of perceptual organization in determining perceived lightness. One of the simplest and most theoretically challenging lightness illusions was described by White. This illusion has been explained with a variety of different models, ranging from low-level filter outputs to computations underlying the extraction of mid-level representations of surfaces. Here, I present a new method for determining the organizational forces that shape this illusion. I show that the spatial context of White's pattern not only transforms the apparent lightness of homogeneous target patches, but can also induce dramatic inversions of figure–ground relationships of textured target regions. These phenomena provide new evidence for the role of scission in causing the lightness illusion experienced in White's effect.
Luminance Gradient Can Break Background-Independent Lightness Constancy
Authors: Logvinenko Alexander D , Kane John
Published: March 2003

A display with a luminance gradient was shown to induce a strong lightness illusion (Logvinenko, 1999 Perception28 803–816). However, a 3-D cardboard model of this display was found to produce a much weaker illusion (less than half that in the pictorial version) despite the fact that its retinal image is practically the same. This is in line with the hypothesis that simultaneous lightness contrast is solely a phenomenon of pictorial perception (Logvinenko et al, 2002 Perception31 73–82). The residual lightness illusion in the 3-D model can be accounted for by the fact that this model is a hybrid display. Specifically, while it is a real object, a pictorial representation (of the illumination gradient) is superimposed on it. Thus, lightness in the 3-D display is a compromise between two opposite tendencies: the background-independent lightness constancy and the lightness illusory shift induced by the luminance gradient.
The Formation of Rhythmic Categories and Metric Priming
Authors: Desain Peter , Honing Henkjan
Published: March 2003

Two experiments on categorical rhythm perception are reported, the object of which was to investigate how listeners perceive discrete rhythmic categories while listening to rhythms performed on a continuous time scale. This is studied by considering the space of all temporal patterns (all possible rhythms made up of three intervals) and how they, in perception, are partitioned into categories, ie where the boundaries of these categories are located. This process of categorisation is formalised as the mapping from the continuous space of a series of time intervals to a discrete, symbolic domain of integer-ratio sequences. The methodological framework uses concepts from mathematics and psychology (eg convexity and entropy) that allow precise characterisations of the empirical results.

In the first experiment, twenty-nine participants performed an identification task with 66 rhythmic stimuli (a systematic sampling of the performance space). The results show that listeners do not just perceive the time intervals between onsets of sounds as placed in a homogeneous continuum. Instead, they can reliably identify rhythmic categories, as a chronotopic time clumping map reveals. In a second experiment, the effect of metric priming was studied by presenting the same stimuli but preceded with a duple or triple metre subdivision. It is shown that presenting patterns in the context of a metre has a large effect on rhythmic categorisation: the presence of a specific musical metre primes the perception of specific rhythmic patterns.
Cognitive Styles: Errors in Directional Judgments
Authors: Nori Raffaella , Giusberti Fiorella
Published: March 2003

Previous studies on spatial memory have shown that, in judging direction, participants are more accurate and faster when a map is aligned with the perspective of the spatial layout they had learned (alignment effect). Rossano and Warren (1989 Perception18 215–229) have shown that when participants have to do a contra-aligned judgment they can either answer correctly, or make alignment or mirror-image errors. We think that the kind of response depends on the different way in which people acquire environmental knowledge: landmark, route, and survey. We hypothesise that landmark and route participants show alignment effects and make, respectively, alignment errors and mirror-image errors, whereas survey participants do not show an alignment effect. An experiment is reported in which participants performed three tasks in order to distinguish their cognitive style. We selected thirty landmark, thirty route, and twenty-eight survey participants. They were then submitted to directional judgment tasks to verify whether the alignment effect was present and to observe the kind of responses. The results revealed that survey participants did not show an alignment effect, and that the kind of errors could depend on the directional judgment task participants had to do, and not only on the cognitive style.
Drawings from Gaia, a Blind Girl
Authors: Kennedy John M
Published: March 2003

Gaia, a totally blind girl, was asked to make raised-line drawings. Gaia's vision at best was peripheral. She draws out of interest, and has drawn since preschool with encouragement from her mother. She was asked to draw objects and scenes involving depth from a vantage point, eg a table from below, two cars (one behind the other), and two parallel rows of apples (receding from her, on a table top). Gaia represented space in her drawings using T-junctions for overlap, height in the picture plane, parallel projection, and inverse projection. That is, Gaia uses features of systems common in sighted children's drawings. The development of drawing in blind and sighted children may be similar in good measure because haptics provides access to many of the same spatial principles as vision.
A Common Oscillator for Perceptual Rivalries?
Authors: Carter Olivia L , Pettigrew John D
Published: March 2003

Perceptual rivalry is an oscillation of conscious experience that takes place despite univarying, if ambiguous, sensory input. Much current interest is focused on the controversy over the neural site of binocular rivalry, a variety of perceptual rivalry for which a number of different cortical regions have been implicated. Debate continues over the relative role of higher levels of processing compared with primary visual cortex and the suggestion that different forms of rivalry involve different cortical areas. Here we show that the temporal pattern of disappearance and reappearance in motion-induced blindness (MIB) (Bonneh et al, 2001 Nature411 798–801) is highly correlated with the pattern of oscillation reported during binocular rivalry in the same individual. This correlation holds over a wide range of inter-individual variation. Temporal similarity in the two phenomena was strikingly confirmed by the effects of the hallucinogen LSD, which produced the same, extraordinary, pattern of increased rhythmicity in both kinds of perceptual oscillation. Furthermore, MIB demonstrates the two properties previously considered characteristic of binocular rivalry. Namely the distribution of dominance periods can be approximated by a gamma distribution and, in line with Levelt's second proposition of binocular rivalry, predominance of one perceptual phase can be increased through a reduction in the predominance time of the opposing phase. We conclude that (i) MIB is a form of perceptual rivalry, and (ii) there may be a common oscillator responsible for timing aspects of all forms of perceptual rivalry.
A Chimeric Point-Light Walker
Authors: Thornton Ian M , Vuong Quoc C , Bülthoff Heinrich H
Published: March 2003

Ambiguity has long been used as a probe into visual processing. Here, we describe a new dynamic ambiguous figure—the chimeric point-light walker—which we hope will prove to be a useful tool for exploring biological motion. We begin by describing the construction of the stimulus and discussing the compelling finding that, when presented in a mask, observers consistently fail to notice anything odd about the walker, reporting instead that they are watching an unambiguous figure moving either to the left or right. Some observers report that the initial percept fluctuates, moving first to the left, then to the right, or vice versa; others always perceive a constant direction. All observers, when briefly shown the unmasked ambiguous figure, have no difficulty in perceiving the novel motion pattern once the mask is returned. These two findings—the initial report of unambiguous motion and the subsequent ‘primed’ perception of the ambiguity—are both consistent with an important role for top–down processing in biological motion. We conclude by suggesting several domains within the realm of biological-motion processing where this simple stimulus may prove to be useful.
The Role of Eyebrows in Face Recognition
Authors: Sadr Javid , Jarudi Izzat , Sinha Pawan
Published: March 2003

A fundamental challenge in face recognition lies in determining which facial characteristics are important in the identification of faces. Several studies have indicated the significance of certain facial features in this regard, particularly internal ones such as the eyes and mouth. Surprisingly, however, one rather prominent facial feature has received little attention in this domain: the eyebrows. Past work has examined the role of eyebrows in emotional expression and nonverbal communication, as well as in facial aesthetics and sexual dimorphism. However, it has not been made clear whether the eyebrows play an important role in the identification of faces. Here, we report experimental results which suggest that for face recognition the eyebrows may be at least as influential as the eyes. Specifically, we find that the absence of eyebrows in familiar faces leads to a very large and significant disruption in recognition performance. In fact, a significantly greater decrement in face recognition is observed in the absence of eyebrows than in the absence of eyes. These results may have important implications for our understanding of the mechanisms of face recognition in humans as well as for the development of artificial face-recognition systems.
Work values of Chinese food service managers
Authors: Simon Wong Chak‐Keung , Manson Chung Kam‐Ho
Published: March 2003

The purpose of this study is to provide relevant information for non‐Chinese hoteliers and caterers who plan to engage in the Chinese food service industry within or beyond China’s boundaries. A total of 152 Chinese restaurant managers working in Hong Kong hotels were surveyed. Factor analysis revealed five underlying dimensions: congenial job context, desirable job content, job status and prospects, self‐fulfilment and accountability, and Confucian work dynamism. Chinese restaurant managers were found to value secure employment, pleasant physical working conditions, high earning and good co‐operation with superiors and peers. Recommendations are made to the concerned government and hotel senior management including: the gender diversity for managerial workforce; managerial competence enhancement for female managers; adoption of unified strategies and plans for the joint ventures or wholly owned foreign hotel companies; introduction of formal vocational education and technical training system for Chinese food service personnel; and, restoration of Chinese ethics through public education and hotel internal training programs.
Practical time series forecasting for the hospitality manager
Authors: Cranage David
Published: March 2003

One of the most basic pieces of information useful to hospitality operations is gross sales, and the ability to forecast them is strategically important. These forecasts could provide powerful information to cut costs, increase efficient use of resources, and improve the ability to compete in a constantly changing environment. This study tests sophisticated, yet simple‐to‐use time series models to forecast sales. The results show that, with slight re‐arrangement of historical sales data, easy‐to‐use time series models can accurately forecast gross sales.
A study of hotel guest perceptions in Mauritius
Authors: Devi Juwaheer Thanika , Lee Ross Darren
Published: March 2003

Hotels in Mauritius have faced difficult times during the 1990s because of changing customer demands and increasing competition from other tourist destinations like the Seychelles, the Pacific and Caribbean islands. The country’s hospitality and tourism sectors are trying to augment and offer more than the traditional “sea, sun and sand” concept which, until recently, has formed the core of the tourism product. Hotels have also not responded satisfactorily to the demands of customers owing to lack of management and staff training in service quality. The purpose of this study was to assess customers’ expectations and perceptions of service provided by hotels of Mauritius and to highlight how the service factors were related to customer satisfaction. The hotel managers’ perceptions of tourists’ expectations and the tourists’ actual expectations were also evaluated. Factor analysis with Varimax rotation was carried out and nine service quality dimensions were derived of 39 service attributes. The results also showed that customers’ perceptions of service quality in the hotel industry for Mauritius fell short of their expectations, with the “empathy” dimension having the largest gap.
Service quality and human resource practices: a theme park case study
Authors: Hickman Jeffrey , Mayer Karl J.
Published: March 2003

This article uses a case study approach to examine how human resource practices affect the delivery of guest services at a large theme park. The theme park uses a four‐pronged approach in managing its human resource function to ensure that service quality standards are maintained. Other hospitality firms can compare their human resource policies to those outlined in this article to guide their own efforts.
Smoking policies in UK pubs: a business opportunity?
Authors: Pratten J.D.
Published: March 2003

The article considers the changes in the structure of the UK pub sector and the falling pattern of trade which occurred at the same time. This meant that the competition within the industry is intense. The major pub‐owning companies enjoy many economies of scale over their independent rivals. These have been considered briefly. Many of the smaller outlets have responded by adapting their pubs to meet the varying requirements of their customers. The demand for pubs with smoke‐free air and the evidence that this will increase trade have been investigated. The threat of legislation has led the industry to establish a voluntary scheme. Reports on its effectiveness have been studied, and a small local study undertaken. It appears that the big companies are swifter than their smaller rivals at taking advantage of this market demand.
Modernizing the Croatian tourism industry
Authors: Bunja Dani
Published: March 2003

Describes some of the characteristics and possibilities for improving the Croatian tourism industry. The main characteristics of the industry are inadequate service levels, infrastructure and low levels of utilization and it is important to understand these and the operating environment. Concludes that the existing personnel and management can do little to improve the quality of service and utilization of the Croatian tourism and hotel industry. To bring about change, modern management practices will be needed, together with the creation of a desirable destination image, innovative forms of investment, and improvement in the transport infrastructure facilities.
The interplay of environment and culture in small firm marketing: a comparative study of the marketing practices of Chinese small firms in Hong Kong and the UK
Authors: Siu Wai‐Sum , Zhu Yi , Kirby David A.
Published: March 2003

Previous research by Siu and Kirby has argued that the broad Western marketing principles are not necessarily fully applicable to, and suitable for, the Chinese socio‐cultural context. To examine this assertion, provides a comprehensive examination of the marketing practices of 18 Chinese small firms in the UK. In so doing, compares the findings with a similar study of 158 Chinese small firms in Hong Kong. The results suggest that the marketing practices of Chinese small firms in the UK are different from their counterparts in Hong Kong. The findings thus lend support to the notion that socio‐cultural values and macro‐economic structure are equally important in determining a firm’s marketing behaviour. Thus, care should be taken before assuming that marketing, as practised in Western situations, is equally applicable across all contexts.
Company performance and objectives reported by first and multi‐generation family companies: a research note
Authors: Westhead Paul
Published: March 2003

Speculative hypotheses relating to firm performance and company objective differences between first and multi‐generation family firms were tested. Bivariate differences were found to be spurious. Results from multivariate multiple regression and logistic regression analyses suggest that the performance of first and multi‐generation firms do not significantly differ in terms of employment growth, the propensity of a firm to be an exporter, and the intensity of internationalization activity. In addition, it was confirmed that the profitability of a family firm was not significantly influenced by its generation stage. It was, however, confirmed that multi‐generation firms were significantly more likely to report a prime company objective is “to enhance the reputation and status of the business in the local community”. In contrast, first generation firms were significantly more likely to report “family objectives have priority over business objectives”. Implications for practitioners and researchers are discussed.
Small firm finance and public policy
Authors: Tucker Jonathan , Lean Jonathan
Published: March 2003

Examines how a finance gap for small firms might be addressed by means of government policy to support informal financing initiatives. A review of both the finance and the government policy literature provides the basis for discussing and conceptualising the financing difficulties faced by small firms, the role of informal financing in alleviating certain of these difficulties and the areas where public policy is currently usefully employed in addressing such financing problems. Undertakes a questionnaire survey to collect data concerning small business awareness and use of informal finance and to identify issues concerning difficulties encountered in gaining access to finance. The results suggest that a debt finance gap may exist for a minority of firms, though an equity finance gap may represent a more significant issue for small firms. Four categories of policy action emerge from the study towards the achievement of economic and social policy objectives.
Entrepreneurial capitalism: if America leads will Europe follow?
Authors: Acs Zoltan J.
Published: March 2003

What differentiates US capitalism from all other forms of industrial capitalism is its historical focus on both the creation of wealth (entrepreneurship) and the reconstitution of wealth (philanthropy). Philanthropy is part of the implicit social contract that continuously nurtures and revitalizes economic prosperity. Much of the new wealth created historically has been given back to the community, to build up the great social institutions that have a positive feedback on future economic growth. This entrepreneurship‐philanthropy nexus has not been fully explored by either economists or the general public. The purpose of this paper is to suggest that US philanthropists – especially those who have made their own fortunes – create foundations that, in turn, contribute to greater and more widespread economic prosperity through knowledge creation. If we do not analyze philanthropy we can understand neither how economic development occurred nor what accounts for US economic dominance.
Structural dissection of alkaline‐denatured pepsin
Authors: Kamatari Yuji O. , Dobson Christopher M. , Konno Takashi
Published: March 2003

It has been established in a number of studies that the alkaline‐denatured state of pepsin (the IP state) is composed of a compact C‐terminal lobe and a largely unstructured N‐terminal lobe. In the present study, we have investigated the residual structure in the IP state in more detail, using limited proteolysis to isolate and characterize a tightly folded core region from this partially denatured pepsin. The isolated core region corresponds to the 141 C‐terminal residues of the pepsin molecule, which in the fully native state forms one of the two lobes of the structure. A comparative study using NMR and CD spectroscopy has revealed, however, that the N‐terminal lobe contributes a substantial amount of additional residual structure to the IP state of pepsin. CD spectra indicate in addition that significant nonnative α‐helical structure is present in the C‐terminal lobe of the structure when the N‐terminal lobe of pepsin is either unfolded or removed by proteolysis. This study demonstrates that the structure of pepsin in the IP state is significantly more complex than that of a fully folded C‐terminal lobe connected to an unstructured N‐terminal lobe.
The oligomerization and ligand‐binding properties of Sm‐like archaeal proteins (SmAPs)
Authors: Mura Cameron , Kozhukhovsky Anna , Gingery Mari , Phillips Martin , Eisenberg David
Published: March 2003

Intron splicing is a prime example of the many types of RNA processing catalyzed by small nuclear ribonucleoprotein (snRNP) complexes. Sm proteins form the cores of most snRNPs, and thus to learn principles of snRNP assembly we characterized the oligomerization and ligand‐binding properties of Sm‐like archaeal proteins (SmAPs) from Pyrobaculum aerophilum (Pae) and Methanobacterium thermautotrophicum (Mth). Ultracentrifugation shows that Mth SmAP1 is exclusively heptameric in solution, whereas Pae SmAP1 forms either disulfide‐bonded 14‐mers or sub‐heptameric states (depending on the redox potential). By electron microscopy, we show that Pae and Mth SmAP1 polymerize into bundles of well ordered fibers that probably form by head‐to‐tail stacking of heptamers. The crystallographic results reported here corroborate these findings by showing heptamers and 14‐mers of both Mth and Pae SmAP1 in four new crystal forms. The 1.9 Å‐resolution structure of Mth SmAP1 bound to uridine‐5′‐monophosphate (UMP) reveals conserved ligand‐binding sites. The likely RNA binding site in Mth agrees with that determined for Archaeoglobus fulgidus (Afu) SmAP1. Finally, we found that both Pae and Mth SmAP1 gel‐shift negatively supercoiled DNA. These results distinguish SmAPs from eukaryotic Sm proteins and suggest that SmAPs have a generic single‐stranded nucleic acid‐binding activity.
Analyses of circular dichroism spectra of membrane proteins
Authors: Wallace B.A. , Lees J.G. , Orry A.J.W. , Lobley A. , Janes Robert W.
Published: March 2003

Circular dichroism (CD) spectroscopy is a valuable technique for the determination of protein secondary structures. Many linear and nonlinear algorithms have been developed for the empirical analysis of CD data, using reference databases derived from proteins of known structures. To date, the reference databases used by the various algorithms have all been derived from the spectra of soluble proteins. When applied to the analysis of soluble protein spectra, these methods generally produce calculated secondary structures that correspond well with crystallographic structures. In this study, however, it was shown that when applied to membrane protein spectra, the resulting calculations produce considerably poorer results. One source of this discrepancy may be the altered spectral peak positions (wavelength shifts) of membrane proteins due to the different dielectric of the membrane environment relative to that of water. These results have important consequences for studies that seek to use the existing soluble protein reference databases for the analyses of membrane proteins.
Anion binding to a protein–protein complex lacks dependence on net charge
Authors: Waldron Travis T. , Modestou Modestos A. , Murphy Kenneth P.
Published: March 2003

The binding of anions to proteins occurs in numerous physiological and metabolic processes. In an effort to understand the factors important in these interactions, we have studied the weak binding of phosphate and sulfate to a protein–protein complex using isothermal titration calorimetry. To our knowledge, this is the first system in which the thermodynamics of anion binding have been determined calorimetrically. By studying both phosphate and sulfate binding and using a range of pH values, the charge on the anion was varied from ∼ −1 to −2. Surprisingly, no dependence of the binding energetics on the charge of the anion was observed. This result indicates that charge–charge interactions are not the dominant factor in binding and suggests the importance of hydrogen bonding in specifically recognizing and coordinating anions.
Polycation‐induced oligomerization and accelerated fibrillation of human α‐synuclein in vitro
Authors: Goers John , Uversky Vladimir N. , Fink Anthony L.
Published: March 2003

The aggregation and fibrillation of α‐synuclein has been implicated as a causative factor in Parkinson's disease and several other neurodegenerative disorders known as synucleinopathies. The effect of different factors on the process of fibril formation has been intensively studied in vitro. We show here that α‐synuclein interacts with different unstructured polycations (spermine, polylysine, polyarginine, and polyethyleneimine) to form specific complexes. In addition, the polycations catalyze α‐synuclein oligomerization. The formation of α‐synuclein–polycation complexes was not accompanied by significant structural changes in α‐synuclein. However, α‐synuclein fibrillation was dramatically accelerated in the presence of polycations. The magnitude of the accelerating effect depended on the nature of the polymer, its length, and concentration. The results illustrate the potential critical role of electrostatic interactions in protein aggregation, and the potential role of naturally occurring polycations in modulating α‐synuclein aggregation.
NMR characterization of interleukin‐2 in complexes with the IL‐2Rα receptor component, and with low molecular weight compounds that inhibit the IL‐2/IL‐Rα interaction
Authors: Emerson S. Donald , Palermo Robert , Liu Chao‐Min , Tilley Jefferson W. , Chen Li , Danho Waleed , Madison Vincent S. , Greeley David N. , Ju Grace , Fry David C.
Published: March 2003

Nuclear magnetic resonance (NMR) methods were employed to study the interaction of the cytokine Interleukin‐2 (IL‐2) with the α‐subunit of its receptor (IL‐2Rα), and to help understand the behavior of small molecule inhibitors of this interaction. Heteronuclear 1H‐15N HSQC experiments were used to identify the interaction surface of 15N‐enriched Interleukin‐2 (15N‐IL‐2) in complex with human IL‐2Rα. In these experiments, chemical shift and line width changes in the heteronuclear single‐quantum coherence (HSQC) spectra upon binding of 15N‐IL‐2 enabled classification of NH atoms as either near to, or far from, the IL‐2Rα interaction surface. These data were complemented by hydrogen/deuterium (H/D) exchange measurements, which illustrated enhanced protection of slowly‐exchanging IL‐2 NH protons near the site of interaction with IL‐2Rα. The interaction surface defined by NMR compared well with the IL‐2Rα binding site identified previously using mutagenesis of human and murine IL‐2. Two low molecular weight inhibitors of the IL‐2/IL‐2Rα interaction were studied: one (a cyclic peptide derivative) was found to mimic a part of the cytokine and bind to IL‐2Rα; the other (an acylphenylalanine derivative) was found to bind to IL‐2. For the interaction between IL‐2 and the acylphenylalanine, chemical shift perturbations of 15N and 15NH backbone resonances were tracked as a function of ligand concentration. The perturbation pattern observed for this complex revealed that the acylphenylalanine is a competitive inhibitor—it binds to the same site on IL‐2 that interacts with IL‐2Rα.
Prediction of protein domain boundaries from sequence alone
Authors: Galzitskaya Oxana V. , Melnik Bogdan S.
Published: March 2003

We present here a simple approach to identify domain boundaries in proteins of an unknown three‐dimensional structure. Our method is based on the hypothesis that a high‐side chain entropy of a region in a protein chain must be compensated by a high‐residue interaction energy within the region, which could correlate with a well‐structured part of the globule, that is, with a domain unit. For protein domains, this means that the domain boundary is conditioned by amino acid residues with a small value of side chain entropy, which correlates with the side chain size. On the one hand, relatively high Ala and Gly content on the domain boundary results in high conformational entropy of the backbone chain between the domains. On the other hand, the presence of Pro residues leads to the formation of hinges for a relative orientation of domains. The method was applied to 646 proteins with two contiguous domains extracted from the SCOP database with a success rate of 63%. We also report the prediction of domain boundaries for CASP5 targets obtained with the same method.