bluuebunny/crossref_metadata_2025 huggingface dataset:
Isotopically resolved calibration of the 285-nm Mgi resonance line for comparison with quasar absorptions
Authors: Salumbides E. J. , Hannemann S. , Eikema K. S. E. , Ubachs W.
Published: October 2006

We have performed high-precision spectroscopy on the 3s21S → 3s3p 1P first resonance line of Mg i at 285 nm. This measurement is motivated by the recent studies comparing observed quasar absorption lines with laboratory measurements in the search for a possible variation of the fine structure constant α. The Mg transition is excited using the up-converted radiation of an injection-seeded Ti : sapphire pulsed laser system, while the frequency of the continuous wave seed light is measured using a femtosecond frequency comb laser. The line positions of the isotopes are fully resolved and have accuracies better than 8 × 10−9. Using terrestrial abundances for the Mg isotopes 24Mg : 25Mg : 26Mg of 78.99 : 10.00 : 11.01, we determine the composite line wavenumber to be 35 051.2808(2) cm−1, which can be compared to the astronomical observations where the isotopic shifts are unresolved.
Evaluation of nutritional and sensorial quality in meal production – NSQE system
Authors: Hering Bethania , Da Costa Proença Rossana Pacheco , De Sousa Anete Araújo , Veiros Marcela Boro
Published: October 2006

In this study, a programme for monitoring critical control points was developed, based on the hazard analysis critical control point (HACCP), in order to determine the nutritional and sensorial quality of menu components in foodservice. A case study was carried out in a foodservice unit where the principles of the HACCP system were implemented. Data were collected during the monitoring of the operational process of the meat‐based menu components through measurements, records and comparisons with previously defined nutritional and sensorial criteria. Nutritional and sensorial hazards were highlighted for the monitored operational stages, along with the critical limits and the form of monitoring. Possible corrective actions were also noted and indicated that they should be adapted to meet each foodservice unit’s situation. Through the application of the proposed theoretical model, the possibility for associating the hygiene–sanitary control and the nutritional and sensorial control analyses was noted.
The meaning of symbols of culinary rules – The food and meals in Elderly care
Authors: Mattsson Sydner Ylva , Fjellström Christina
Published: October 2006

In Sweden, meals are provided to the elderly living in various types of institutions. This paper discusses how food in this context is expressed as substance and symbols. It focuses on the social organization surrounding food provision in residential care homes, from considerations in menu planning to the final presentation of the meal. This encompasses the diet of the elderly and how the norms, values and behaviours of different social identities in such an organization shape food provision. The empirical work is based on participant observations in four residential care homes. In each home, the manager of the restaurant kitchen was responsible for menu planning for all meals served to the elderly. This meant that they planned menus they thought were suitable for elderly people, i.e. most of the dishes were plain Swedish food. The dishes presented on the menu card symbolized a specific taste and shape. These different dishes are traditionally and variously connected to different kinds of trimmings. Although symbols such as specific taste, shape and trimmings were linked to the dish when the manager planned the menu, the servings were often presented with some variation in reality. The cooks rarely used a written recipe; they sometimes interpreted a dish with a particular name differently, and they did not always use the ‘indicated’ ingredients associated with these dishes. The elderly who ate their meals in the restaurants could wish for and had access to a wide range of condiments. At the units where the staff served the meals, however, the final servings were often far from the symbols associated with each specific dish. Thus, the cooks, and moreover the staff, lacked knowledge about the ‘right’ trimmings, were unable or did not care to offer these traditional symbols, which are important to the elderly meal situation as a whole.
Labor Force Trends and Immigration in Europe
Authors: Feld Serge
Published: October 2006

Labor force trends up to 2025 for the fifteen countries (before May 1, 2004) of the European Community are examined. Will demographic decline have an early effect on manpower volume? An estimation is made to determine whether present migratory flow levels in these countries will be sufficient to counter labor force stagnation. Manpower trend scenarios are proposed for each country. They show highly contrasting situations. These countries favor different policies for mobilizing and increasing their manpower volume. There is wide divergence between the various EU countries as concerns their demographic situation and labor force participation rate as well as their social security systems. Considering these highly diverse national characteristics, the difficulty in arriving at a consensus on EU migratory policy harmonization is stressed.
Stepping from Illegality to Legality and Advancing towards Integration: The Case of Immigrants in Greece
Authors: Glytsos Nicholas P.
Published: October 2006

This paper highlights how the social and economic situation of immigrants changes after their formal legalization and discusses what they have to go through for their complete integration. Legalization can hardly solve the problem of immigrant employment, nor can it pull all immigrants out of the underground labor market and integrate them into the Greek economy and society. The process towards complete integration is painful and involves a series of successive phases of various durations. During this period, apart from economic conditions, various institutional and cultural factors can hinder or delay integration. With respect to economic integration, immigrants seem to fare rather well. Their official unemployment rate is only slightly higher than the Greek unemployment rate, the two rates converging over time. This suggests increasing relative opportunities for immigrant employment, precarious or stable as it might be. Immigrant jobs come as a result of their flexible adjustment to the needs of the labor market – official or underground – compared to the inflexibility in the supply of Greek workers, due to labor mismatches and relatively high reservation wages. Wages of immigrants are generally lower, but are approaching the wages of their Greek counterparts. Educated immigrants much more than educated Greeks are forced by the circumstances to exercise jobs not measuring up to their qualifications.
Does Selective Migration Matter? Explaining Ethnic Disparities in Educational Attainment among Immigrants' Children
Authors: Feliciano Cynthia
Published: October 2006

Understanding why some national-origin groups excel in school while others do not is an enduring sociological puzzle. This paper examines whether the degree of immigrants' educational selectivity – that is, how immigrants differ educationally from non-migrants in the home country – influences educational outcomes among groups of immigrants' children. This study uses published international data and U.S. Census and Current Population Survey data on 32 immigrant groups to show that as immigrants' educational selectivity increases, the college attainment of the second generation also increases. Moreover, the more positive selection of Asian immigrants helps explain their second generations' higher college attendance rates as compared to Europeans, Afro-Caribbeans, and Latinos. Thus, the findings suggest that inequalities in relative pre-migration educational attainments among immigrants are often reproduced among the next generation in the United States.
The Retention of Newcomers in Second- and Third-Tier Canadian Cities
Authors: Krahn Harvey , Derwing Tracey M. , Abu-Laban Baha
Published: October 2006

The federal government of Canada and several provincial governments are anxious to promote a more balanced distribution of immigrants across the country. Currently, 89 percent of all newcomers settle in large cities, 75 percent in Toronto, Vancouver, and Montreal alone. This study examines the internal migration of refugees destined to second-and third-tier cities in Alberta. Their decisions to stay in or leave these communities have significant policy implications. The economic vitality of urban centers, the existence of compatriot communities, and the recognition of immigrant skills and educational credentials all contribute to the retention of newcomers in second- and third-tier cities.
Incorporation, Transnationalism, and Gender: Immigrant Incorporation and Transnational Participation as Gendered Processes
Authors: Itzigsohn José , Giorguli-Saucedo Silvia
Published: October 2006

This article analyzes immigrant incorporation and transnational participation as gendered experiences. The results indicate that the incorporation of immigrants is a complex process affected negatively by class and racial exclusion and positively by their knowledge of U.S. society. The analysis also indicates that incorporation and transnational participation are concurrent and intertwined processes. Our results show that gender matters in the analysis of immigrant incorporation. The experiences of immigrant men and women share a lot in common as they confront similar challenges, but are also affected differently by the most relevant factors in the process of incorporation and transnational participation.
Hypertrophic osteopathy associated with infective endocarditis in an adult boxer dog
Authors: Dunn M. E. , Blond L. , Letard D. , DiFruscia R.
Published: October 2006

A 20‐month‐old, entire male boxer dog was presented with lethargy and intermittent shifting limb lameness. Diagnostic tests revealed aortic valve vegetations suggestive of infective endocarditis causing severe aortic outflow obstruction, and hypertrophic osteopathy of all four limbs. The dog was treated symptomatically and euthanased four days later. The association of infective endocarditis and hypertrophic osteopathy has been poorly documented in the veterinary literature. The pathogenesis of hypertrophic osteopathy is unknown; however, four theories have been put forth to explain this disease: pulmonary shunting, vagal nerve stimulation, humoral substances produced by neoplastic cells and megakaryocyte/platelet clump hypothesis.
Survival costs of adult dormancy and the confounding influence of size in lady's slipper orchids, genus Cypripedium
Authors: Shefferson Richard P.
Published: October 2006

Adult whole‐plant dormancy is a phenomenon in which a perennial, herbaceous plant does not sprout for one or more years. Although previous studies have noted a cost of dormancy to survival, none have accounted for the potentially confounding influence of size variation on this relationship. I asked whether the probabilities of dormancy and survival in dormancy‐prone plants vary with size, possibly creating the appearance of a life‐history tradeoff between survival and dormancy. I censused sympatric populations of three lady's slipper orchid taxa, Cypripedium parviflorum, C. candidum, and C.×andrewsii, in an 11‐year study (1994 to 2004) at Gavin Prairie, Illinois, USA. Annual dormancy and survival trends were modeled using Cormack‐Jolly‐Seber mark‐recapture analysis, while stage‐specific survival and stratum‐transitions (i.e. probability of transitioning among stages conditional upon survival) were modeled with multi‐strata mark‐recapture analysis. Annual dormancy probabilities and transition probabilities to and from dormancy varied synchronously among taxa, while trends in survival did not. Both survival and dormancy varied with number of sprouts in the previous year, positively in the case of the former and negatively in the case of the latter. Accounting for plant size in this way eliminated any variation in survival by life‐history stage, with dormant plants surviving at the same rate as non‐dormant plants of the same size. Transitions among stages did not vary with plant size. My results suggest common climatic cues to dormancy, and suggest caution in inferring costs of dormancy from studies in which plant size is not controlled, as such costs may be artifacts of smaller plants being more dormant‐prone and less likely to survive.
Neurokinin‐1 receptor desensitization attenuates cutaneous active vasodilatation in humans
Authors: Wong Brett J. , Minson Christopher T.
Published: October 2006

To date, the neurotransmitter(s) and pathways involved in cutaneous active vasodilatation are not fully understood. The purpose of this study was to determine the potential involvement of neurokinin‐1 (NK1) receptors to active vasodilatation. Our experimental model exploited our previous findings that repeated microdialysis infusions of substance P desensitize the NK1 receptors and that substance P‐induced vasodilatation contains a substantial nitric oxide (NO) component. Eleven subjects were equipped with four microdialysis fibres on the ventral forearm. Site 1 served as a control and received a continuous infusion of Ringer solution. Site 2 received a continuous infusion of 10 mm l‐NAME to inhibit NO synthase. Site 3 received a 10 μm dose of substance P to desensitize the NK1 receptors prior to whole‐body heating. Site 4 received a 10 μm dose of substance P combined with 10 mm l‐NAME. Red blood cell (RBC) flux was measured via laser‐Doppler flowmetry, and cutaneous vascular conductance (CVC) was calculated as RBC flux/mean arterial pressure and normalized to maximal vasodilatation via 28 mm sodium nitroprusside. Substance P was infused for 15 min at 4 μl min−1 in sites 3 and 4, and skin blood flow was allowed to return to baseline (∼45–60 min). Subjects then underwent a period of whole‐body heat stress to raise oral temperature 0.8–1.0°C above baseline. Pretreatment with substance P increased CVC to 48 ± 2% CVCmax, which was significantly greater than for sites pretreated with substance P combined with l‐NAME (27 ± 2% CVCmax; P < 0.001). During whole‐body heating, CVC in control sites increased to 69 ± 3% CVCmax. Sites pretreated with substance P (48 ± 3% CVCmax) were significantly reduced compared to control sites (P < 0.001). The CVC response to whole‐body heat stress in l‐NAME sites was significantly reduced (32 ± 3% CVCmax; P < 0.001) compared to both control sites and sites pretreated with substance P. The CVC response to whole‐body heating was nearly abolished in sites pretreated with substance P combined with l‐NAME (20 ± 2% CVCmax) and was significantly reduced compared to the other three sites (all P < 0.001). These data suggest NK1 receptors contribute to active vasodilatation and that combined NK1 receptor desensitization and NO synthase inhibition further diminishes active vasodilatation.
Transcranial direct current stimulation of the primary motor cortex affects cortical drive to human musculature as assessed by intermuscular coherence
Authors: Power Hollie A. , Norton Jonathan A. , Porter Cheryl L. , Doyle Zoe , Hui Isaiah , Chan K. Ming
Published: October 2006

Intermuscular coherence analysis can be used to assess the common drive to muscles. Coherence in the β‐frequency band (15–35 Hz) is thought to arise from common cortical sources. Intermuscular coherence analysis is a potentially attractive tool for the investigation of motor cortical excitability changes because it is non‐invasive and can be done relatively quickly. We carried out this study to test the hypothesis that intermuscular coherence analysis was able to detect cortical excitability changes in healthy subjects following transcranial direct current stimulation (tDCS). tDCS has been shown to increase (anodal stimulation) or decrease (cathodal stimulation) the size of the muscle potential evoked by TMS. We found that anodal tDCS caused an increase in motor evoked potential (MEP) size that was paralleled by an increase in β‐band intermuscular coherence. Similarly, the reduction in MEP size produced by cathodal tDCS was paralleled by a reduction in β‐band intermuscular coherence, while sham stimulation did not result in any change in either MEP amplitude or β‐band intermuscular coherence. The similar pattern of change observed for MEP and intermuscular coherence may indicate similar mechanisms of action, although this cannot be assumed without further investigation. These changes do suggest that at least some of the action of tDCS is on cortical networks, and that combined tDCS and intermuscular coherence analysis may be useful in the diagnosis of pathologies affecting motor cortical excitability.
Muscarinic acetylcholine receptor knockout mice show distinct synaptic plasticity impairments in the visual cortex
Authors: Origlia Nicola , Kuczewski Nicola , Aztiria Eugenio , Gautam Dinesh , Wess Jürgen , Domenici Luciano
Published: October 2006

In the present report, we focused our attention on the role played by the muscarinic acetylcholine receptors (mAChRs) in different forms of long‐term synaptic plasticity. Specifically, we investigated long‐term potentiation (LTP) and long‐term depression (LTD) expression elicited by theta‐burst stimulation (TBS) and low‐frequency stimulation (LFS), respectively, in visual cortical slices obtained from different mAChR knockout (KO) mice. A normal LTP was evoked in M1/M3 double KO mice, while LTP was impaired in the M2/M4 double KO animals. On the other hand, LFS induced LTD in M2/M4 double KO mice, but failed to do so in M1/M3 KO mice. Interestingly, LFS produced LTP instead of LTD in M1/M3 KO mice. Analysis of mAChR single KO mice revealed that LTP was affected only by the simultaneous absence of both M2 and M4 receptors. A LFS‐dependent shift from LTD to LTP was also observed in slices from M1 KO mice, while LTD was simply abolished in slices from M3 KO mice. Using pharmacological tools, we showed that LTP in control mice was blocked by pertussis toxin, an inhibitor of Gi/o proteins, but not by raising intracellular cAMP levels. In addition, the inhibition of phospholipase C by U73122 induced the same shift from LTD to LTP after LFS observed in M1 single KO and M1/M3 double KO mice. Our results indicate that different mAChR subtypes regulate different forms of long‐term synaptic plasticity in the mouse visual cortex, activating specific G proteins and downstream intracellular mechanisms.
Analysis of the Chatter Instability in a Nonlinear Model for Drilling
Authors: Campbell Sue Ann , Stone Emily
Published: October 2006

In this paper we present stability analysis of a non-linear model for chatter vibration in a drilling operation. The results build our previous work [Stone, E., and Askari, A., 2002, “Nonlinear Models of Chatter in Drilling Processes,” Dyn. Syst., 17(1), pp. 65–85 and Stone, E., and Campbell, S. A., 2004, “Stability and Bifurcation Analysis of a Nonlinear DDE Model for Drilling,” J. Nonlinear Sci., 14(1), pp. 27–57], where the model was developed and the nonlinear stability of the vibration modes as cutting width is varied was presented. Here we analyze the effect of varying cutting depth. We show that qualitatively different stability lobes are produced in this case. We analyze the criticality of the Hopf bifurcation associated with loss of stability and show that changes in criticality can occur along the stability boundary, resulting in extra periodic solutions.
Optimal Inputs for Phase Models of Spiking Neurons
Authors: Moehlis Jeff , Shea-Brown Eric , Rabitz Herschel
Published: October 2006

Variational methods are used to determine the optimal currents that elicit spikes in various phase reductions of neural oscillator models. We show that, for a given reduced neuron model and target spike time, there is a unique current that minimizes a square-integral measure of its amplitude. For intrinsically oscillatory models, we further demonstrate that the form and scaling of this current is determined by the model’s phase response curve. These results reflect the role of intrinsic neural dynamics in determining the time course of synaptic inputs to which a neuron is optimally tuned to respond, and are illustrated using phase reductions of neural models valid near typical bifurcations to periodic firing, as well as the Hodgkin-Huxley equations.
A Review of a Few Topics in Piezoelectricity
Authors: Yang Jiashi
Published: October 2006

This is a review article on a few special topics in piezoelectricity: gradient and nonlocal theories, fully dynamic theory with Maxwell equations, piezoelectric semiconductors, and motions of rotating piezoelectric bodies. They all require some extension of the classical theory of piezoelectricity. They are relatively new, more advanced, and growing subjects with applications or potential applications in various electromechanical devices. The article contains 209 references. (In memory of Raymond D. Mindlin (1906–1987)).
Back side exposure of variable size through silicon vias
Authors: Rowbotham T. , Patel J. , Lam T. , Abhulimen I. U. , Burkett S. , Cai L. , Schaper L.
Published: October 2006

The formation of microscale vertical interconnects enables three-dimensional interconnects for chip stacking applications. These vertical interconnects, or metal filled through silicon vias, are formed by a series of processing steps that include silicon etch, insulation/barrier/seed deposition, electroplated Cu to fill via, wafer grinding and thinning, and back side processing for contacts. Variable diameter size vias residing in the same wafer allow flexibility in integration for many applications. Producing variable size through silicon vias (VTSVs) on a single wafer is challenging. This article presents details regarding the exposure of VTSV using a unique wafer back side processing technique. Via diameters are in the range of 10–30μm and etch depth varies with via diameter due to the commonly observed reactive ion etch lag. In this approach, the finished wafers are thicker than that produced in a previous project which reduces the risk of wafer breakage during the debonding process.
Chemical analysis of deposits formed on the reactor walls during silicon and metal gate etching processes
Authors: Le Gouil A. , Pargon E. , Cunge G. , Joubert O. , Pelissier B.
Published: October 2006

One major challenge in plasma etching processes for integrated circuit’s fabrication is to achieve wafer-to-wafer repeatability. This requires an excellent control of the plasma chamber wall conditions. For gate etching processes this is achieved by cleaning the interior surfaces of the plasma chamber with appropriate plasma chemistries after each wafer is etched. This strategy relies on the knowledge of the chemical composition of the layer coated on the reactor walls after the etching process. However, this is generally not the case and the chemical nature of this layer varies significantly with the etching conditions. In particular, the chemical nature of the coatings formed on the reactor walls during gate etching processes, which require up to seven successive etching steps in different plasma chemistries, has never been investigated in detail. In addition, the introduction of metals and high k in the gate stack can lead to types of coatings on the reactor walls. In the present article, we have used x-ray photoelectron spectroscopy analysis to monitor the chemical nature of the layers coated on the reactor walls after each step of silicon gate patterning steps. The results are compared to a metal (TiN) gate etching process, which includes nine different etching steps.
Converging lithography by combination of electrostatic layer-by-layer self-assembly and 193nm photolithography: Top-down meets bottom-up
Authors: Hah Jung Hwan , Mayya Subramanya , Hata Mitsuhiro , Jang Yun-Kyeong , Kim Hyun-Woo , Ryoo Manhyoung , Woo Sang-Gyun , Cho Han-Ku , Moon Joo-Tae
Published: October 2006

Photolithography is a part of the top-down approach that forms the basis of various processes in the semiconductor industry, which has followed Moore’s law for new generations of devices. However, as feature sizes are scaled to the nanometer regime, the bottom-up approach is being touted as a means to solve problems arising due to size reduction. Here the authors report a result based on the convergence of 193nm lithography and electrostatic layer-by-layer assembly, which overcomes the resolution limit of photolithography and also assists self-assembly to form complex patterns. Their result shows that hurdles associated with top-down approaches to further device scaling can be overcome by introducing bottom-up approaches.
Study of metal gate deposition by magnetron sputtering
Authors: Ye Mengqi , Liu Zhendong , Ding Peijun , Hung Steven , Ahmed Khaled
Published: October 2006

A systematic study on metal gate deposition by magnetron sputtering is presented. The authors compared the interface trap density (Dit) in metal-oxide-semiconductor capacitors with metal gate deposited by either conventional magnetron sputtering, atomic layer deposition followed by conventional sputter deposition, or a newly developed magnetron sputtering technology. The results indicate that the new sputtering technology can minimize plasma damage to the underlying ultrathin dielectric film and achieve Dit values of less than 1011cm−2eV−1. Experimental data on plasma characterization using ion collectors and Langmuir probe are presented. The effects of metal gate deposition methods, dielectric film thickness, and sputtering parameters such as sputtering power, pressure, and pulsed dc sputtering are discussed. It is found that pulsed dc sputtering generates higher Dit values. In the new sputtering process, the flux and the energy of the ions arriving at the substrate surface are several times lower, and the floating voltage fluctuations on the substrate surface are about one order of magnitude lower, effectively preventing potential plasma damage to the underlying dielectric films by minimizing energetic particle bombardment and charging impact.
Multiparameter characterization of cluster ion beams
Authors: Nicolaescu D. , Takaoka G. H. , Ishikawa J.
Published: October 2006

Multiparameter characterization results for cluster ion beams are presented. Size distributions for cluster ions generated under various conditions are measured using time-of-flight mass spectrometry. The experimental data are initially modeled by analytical relationships using the exponentially modified Gaussian function. A beam trajectory model is then imposed to reveal the intrinsic dependence of the size distribution parameters on each of the main beam generation parameters.
Thickness and Fourier transform infrared peak instability in silicon dioxide thin films deposited using electron-gun deposition
Authors: Cornell T. , Nightingale J. R. , Pathak S. , Hornak L. A. , Korakakis D.
Published: October 2006

The need for portable biosensing devices has been apparent for several years; however, practical fieldable devices have continued to be challenging to achieve due to their inherent need for sensitivity while maintaining environmental robustness. This is especially true for optical biosensors as small changes in the device’s materials’ properties or thickness may render the device ineffective. By using Fourier transform infrared spectroscopy and ellipsometry techniques the authors have studied the behavior of silicon dioxide films deposited using electron-gun deposition when exposed to atmosphere and water. Experiments have shown that strain in the film is released when the films absorb water, which can be seen from changes in the Si–O stretching bond and film thickness.
Investigation of surface roughening of low-k films during etching using fluorocarbon plasma beams
Authors: Yin Yunpeng , Rasgon Stacy , Sawin Herbert H.
Published: October 2006

The surface roughness evolution of solid organosilicate glass (OSG) and methylsilsesquioxane spin-on porous low-k films after etching in C2F6∕Ar plasmas was characterized as a function of ion bombardment energy, ion fluence reaching the surface (or, equivalently, the etching time), ion impingement angle, and plasma polymerization propensity in a newly designed plasma beam system in which the plasma chemistry, ion energy, ion flux, and ion incident angle can be adjusted independently. A polymerization-induced micromasking mechanism was proposed to explain the surface roughening of these low-k films. The porous structure in the substrate plays a critical role in the film roughening evolution. This effect can be understood using the concept of pore filling with polymeric deposits that etch more slowly under fluorocarbon plasma exposure. Upon exposure to etching, the polymer forms micromasks that induce roughening. Under the same etching conditions, the solid OSG film remains smooth during etching because only a fairly thin and uniform layer of polymer deposits on the surface of solid OSG substrates during the etching in C2F6∕Ar plasmas. Consequently, the inhomogeneity caused by the polymer deposition is not sufficient to induce micromasking in the absence of surface inhomogeneities. Additionally, the roughness level of the porous low-k film etched in C2F6∕Ar plasma is primarily related to the film thickness removed, although it also increases with the ion bombardment energy; no similar trend was observed on nonporous OSG films under the same etching conditions. Striations formed when etching porous low-k films at grazing angles. The striation formation is mainly due to shadowing effects, although conditions of net polymer deposition quenched the striation formation.
Novel electron-beam-induced reaction of a sulfonium salt in the solid state
Authors: Enomoto Kazuyuki , Moon Seongyun , Maekawa Yasunari , Shimoyama Junji , Goto Kazuyuki , Narita Tadashi , Yoshida Masaru
Published: October 2006

The electron-beam (EB)-induced reaction of triphenylsulfonium methanesulfonate (1-Ms) in the solid state afforded the benzene-substituted product, biphenyldiphenylsulfonium methanesulfonate (2-Ms), which has not been observed by either photolysis or EB-induced reaction in a solution. Biphenyl salt 2-Ms was accumulated as an intermediate product at an early stage and consequently decomposed to diphenylsulfide (3) and three regioisomers of phenylthiobiphenyls (4). The kinetic data of both formation and consumption of 2-Ms revealed that the biphenyl salt 2-Ms exhibited 3.7 times greater kinetic constants for consumption than that of 1-Ms. The EB-induced reaction of benzene-substituted triphenylsulfonium salts, p-biphenyldiphenylsulfonium methanesulfonate(2p-Ms) and (4-phenylthiophenyl)diphenylsulfonium methanesulfonate (7), showed the consumption rates of 3.8 and 5.7 times greater than that of 1-Ms. The sulfonium salts with aromatic counteranions showed somewhat higher reactivity than those with aliphatic counteranions. Accordingly, it is concluded that the triphenylsulfonium salts having aryl groups, which exhibit lower ionization potential, in both cation and anion moieties should exhibit greater decomposition rates. Detailed kinetic analysis of 1-Ms revealed that the EB-induced reaction of 1-Ms comprises two disparate pathways, one pathway is a unimolecular rearrangement via the lowest excited state leading to only orthoisomer of 4 and the other is a bimolecular displacement of phenyl radical via the upper excited state leading to 2-Ms and 3.
Modeling HfO2 atomic layer chemical vapor deposition on blanket wafer, via, and trench structures using HfCl4∕H2O
Authors: Stout Phillip J. , Adams Vance , Ventzek Peter L. G.
Published: October 2006

Atomic layer chemical vapor deposition (CVD) of HfO2 on blanket wafer, trench, and via structures using a HFCl4∕H2O chemistry has been modeled. The feature modeling uses a Monte Carlo model (three-dimensional Papaya) as well as calculation results from CVD reactor and molecular dynamics chemistry models. Added to the feature scale model, Papaya, is the capability to input time dependent fluxes from the CVD reactor model as well as specify a multistep process for tens of cycles. HCl products from HfCl4+OH– and H2O+Cl– reactions are more likely to react within a feature than at the field which reduces the OH coverage within feature, limiting maximum coverage achievable with a pulse. Given the particulars of the cross flow reactor’s design, features downstream of the inlet during the H2O pulse will have a higher percentage of the HCl reaction product to the surface and desorption of HfCl4 causing differences in the coverage fraction and deposition rate across the wafer. Characterized are the minimum pulse times sufficient for surface reaction saturation on blanket wafers versus deposition on trench and via features. The Cl fraction in the deposit is greater at the surface than in the bulk, reaches a steady state after tens of cycles, has reduced minimum and maximum values as coverage is reduced, and total is reduced as feature aspect ratio is increased.
Comparison of microcantilever Hg sensing behavior with thermal higher order modes for as-deposited sputtered and thermally evaporated Au films
Authors: Kadam Ashwini R. , Nordin Gregory P. , George Michael A.
Published: October 2006

As-deposited sputtered and thermally evaporated Au films are studied for Hg sensing with rectangular Si microcantilevers. Microcantilever deflection and frequency shifts in the first four thermally induced flexural modes are measured for each type of Au film as a function of Hg exposure. All thermally induced higher order modes show shifts in their frequencies for Hg exposures when the Au is sputter deposited whereas typically only the third and fourth order modes show frequency shifts when the Au is thermally evaporated. A technique is employed in order to vary Au coverage along a microcantilever surface. The shifts in the thermal microcantilever modes upon Hg exposure are thus studied as a function of fractional Au coverage along the microcantilever surface. Microcantilevers having various coverages of either sputtered or thermally evaporated Au films show a distinct response to Hg exposure. From both the deflection and spectral shifts it is observed that sputtered films give better response to Hg than thermally evaporated films when the Au is coated along the entire length of the microcantilever.
Atomic layer deposition of Ta-based thin films: Reactions of alkylamide precursor with various reactants
Authors: Maeng W. J. , Park Sang-Joon , Kim H.
Published: October 2006

The growth mechanisms and film properties of atomic layer deposition (ALD) Ta-based thin films were investigated from alkylamide precursor [Ta(NMe2)5, (PDMAT)]. The reactions of PDMAT with various reactants including water, NH3, oxygen, and hydrogen plasma were studied and the resulting film properties were investigated by various analysis techniques. For TaN ALD from NH3 and H plasma, the films were contaminated by considerable amount of carbon, while the Ta2O5 deposited from water and O plasma were quite pure. Also, nitrogen was incorporated for ALD from PDMAT and H plasma, while no nitrogen incorporation was observed for O-plasma based plasma enhanced-ALD of Ta2O5 except at high deposition temperature over 300°C. The results were comparatively discussed focusing on the differences in growth mechanism depending on reactants.
Prospect of cobalt-mix-tetraethoxysilane method on localized lateral growth of carbon nanotubes for both p- and n-type field effect transistors
Authors: Chen Bae-Horng , Lin Horng-Chih , Huang Tiao-Yuan , Wei Jeng-Hua , Hwang Chien-Liang , Lo Po-Yuan , Tsai Ming-Jinn , Chao Tien Sheng
Published: October 2006

To apply carbon nanotubes (CNTs) to nanoelectronics, researchers must effectively control the placement and manipulation of massive numbers of CNTs. In this work, we demonstrate a precise growth of single-walled carbon nanotubes (SWNT) on preassigned locations with only cobalt as catalyst. This is in contrast to the laborious and time-consuming physical manipulation of numerous nanotubes one at a time used in the conventional approach. Laterally grown CNTs were accomplished in preassigned areas using an integrated circuit compatible process in this study. In order to synthesize SWNT as the channel of a field effect transistor (FET), the cobalt-mix-tetraethoxysilane (CMT) solution and catalytic chemical vapor deposition were used. The CMT solution has the unique property of well dispersing the cobalt catalyst and uniformly embedding it in predetermined locations after the CMT solution has solidified. Our results show that laterally grown bundled-CNTs could be formed in atmospheric chemical vapor deposition with ethanol, by properly controlling the temperature of process, the process time, and the hydrogen reduction time. Since our bundled-CNTs were exposed to the air, all the as-grown CNT-FETs we manufactured exhibit p-type characteristics. Furthermore, we also demonstrate air-stable n-type CNT-FETs successfully without resorting to any additional and complicated annealing process by simply depositing a silicon nitride film on the as-grown p-type devices by plasma enhanced (PECVD) at 390°C. The use of prepatterned catalyst islands, CVD method, and flexibility of simultaneously manufacturing both n- and p-type CNT-FETs may open a new era for applications of CNT-based nanoelectronics.
Al
Ga
N
∕
Ga
N
high electron mobility transistors on Si∕SiO2/poly-SiC substrates
Authors: Anderson T. J. , Ren F. , Voss L. , Hlad M. , Gila B. P. , Covert L. , Lin J. , Pearton S. J. , Bove P. , Lahreche H. , Thuret J.
Published: October 2006

Al Ga N ∕ Ga N high electron mobility transistors were grown by molecular beam epitaxy on Si on poly-SiC substrates formed by the Smart Cut™ process. The Smart Cut™ approach is an alternative solution to provide both a high resistivity and an excellent thermal conductivity template needed for power applications. Although the structure has not been optimized, devices with 0.7μm gate length show breakdown voltage of >250V, fT of 18GHz, and fmax of 65GHz.
Low resistance, unannealed, Ohmic contacts to p-type In0.27Ga0.73Sb
Authors: Champlain James G. , Magno Richard , Boos J. Brad
Published: October 2006

Unannealed Pd∕Pt∕Au contacts to p-type In0.27Ga0.73Sb were fabricated and measured. Relatively high hole mobilities, with respect to similarly doped InP-lattice-matched materials, and associated low sheet resistances were measured for the p-type In0.27Ga0.73Sb material. The unannealed Pd∕Pt∕Au contacts were found to be Ohmic in nature; and for a hole density of 2.9×1019cm−3 and a mobility of 160cm2∕Vs, a specific contact resistance of 7.6×10−8Ωcm2 was measured.
Plasma doping implant depth profile calculation based on ion energy distribution measurements
Authors: Godet L. , Fang Z. , Radovanov S. , Walther S. , Arevalo E. , Lallement F. , Scheuer J. T. , Miller T. , Lenoble D. , Cartry G. , Cardinaud C.
Published: October 2006

In traditional beamline implantation, the incident ion mass and energy are well known parameters and simulation programs are available to predict the implant profiles. In plasma based ion implantation, all ionized species present in the plasma are extracted and implanted by applying negative voltage pulses to the wafer. Therefore, prediction of implant profile is more complicated since it requires the knowledge of relative abundance of each ion species as well as their energy distribution prior to entering the wafer surface. This information is not readily available using conventional plasma characterization techniques because most of them measure plasma bulk properties. In order to collect the information needed for predicting plasma implant profiles, an ion mass and energy spectrometer is installed at the wafer level to allow in situ measurement of ion mass and energy distribution. In this paper, BF3 plasma in the pressure range from 30to250mTorr is studied. The relative flux and energy distribution of B+, BF+, BF2+, and BF3+ ions striking the wafer surface with energies up to 1keV are measured. As expected, no energy contamination was observed during a plasma doping implantation and the maximum energy of the ions is defined by the cathode voltage. Based on the spectrometer data, a series of simulations was performed to calculate the boron and fluorine dopant depth profiles. The calculated profiles were in good agreement with secondary ion mass spectrometry (SIMS) results and give some additional explanations of the unique surface-peaked SIMS profile of plasma doping implantation.
Surface roughness exacerbated performance degradation in silicon nanowire transistors
Authors: Basu D. , Gilbert M. J. , Banerjee S. K.
Published: October 2006

Scaling of silicon devices is fast approaching the limit where a single gate will fail to retain an effective control over the channel region. Of the alternative devices being researched, silicon nanowire transistors (SNWTs) show great promise in terms of scalability, performance, and ease of fabrication. In this work, the authors present the results of self-consistent, three-dimensional fully quantum mechanical simulations of SNWTs to show the role of surface roughness (SR) on the device parameter variation of SNWTs. The authors find additional quantum interference to take place when SR is taken into account in addition to a discrete impurity distribution. Due to this, the variations of the SNWT operational parameters increase about their mean value, indicating a performance concern. However, it is also seen that the quantum interferences are dependent on the dopant locations to a large extent, and for devices with preferential dopant configurations, these effects can be overcome to obtain nearly ballistic behavior.
Biologically Based Computational Models of High-Level Cognition
Authors: O'Reilly Randall C.
Published: October 2006

Computer models based on the detailed biology of the brain can help us understand the myriad complexities of human cognition and intelligence. Here, we review models of the higher level aspects of human intelligence, which depend critically on the prefrontal cortex and associated subcortical areas. The picture emerging from a convergence of detailed mechanistic models and more abstract functional models represents a synthesis between analog and digital forms of computation. Specifically, the need for robust active maintenance and rapid updating of information in the prefrontal cortex appears to be satisfied by bistable activation states and dynamic gating mechanisms. These mechanisms are fundamental to digital computers and may be critical for the distinctive aspects of human intelligence.
Action of TFII-I Outside the Nucleus as an Inhibitor of Agonist-Induced Calcium Entry
Authors: Caraveo Gabriela , van Rossum Damian B. , Patterson Randen L. , Snyder Solomon H. , Desiderio Stephen
Published: October 2006

TFII-I is a transcription factor and a target of phosphorylation by Bruton's tyrosine kinase. In humans, deletions spanning the
TFII-I
locus are associated with a cognitive defect, the Williams-Beuren cognitive profile. We report an unanticipated role of TFII-I outside the nucleus as a negative regulator of agonist-induced calcium entry (ACE) that suppresses surface accumulation of TRPC3 (transient receptor potential C3) channels. Inhibition of ACE by TFII-I requires phosphotyrosine residues that engage the SH2 (Src-homology 2) domains of phospholipase C–g (PLC-g) and an interrupted, pleckstrin homology (PH)–like domain that binds the split PH domain of PLC-g. Our observations suggest a model in which TFII-I suppresses ACE by competing with TRPC3 for binding to PLC-g.
Extending Top-Down Mass Spectrometry to Proteins with Masses Greater Than 200 Kilodaltons
Authors: Han Xuemei , Jin Mi , Breuker Kathrin , McLafferty Fred W.
Published: October 2006

For characterization of sequence and posttranslational modifications, molecular and fragment ion mass data from ionizing and dissociating a protein in the mass spectrometer are far more specific than are masses of peptides from the protein's digestion. We extend the ∼500-residue, ∼50-kilodalton (kD) dissociation limitation of this top-down methodology by using electrospray additives, heated vaporization, and separate noncovalent and covalent bond dissociation. This process can cleave 287 interresidue bonds in the termini of a 1314-residue (144-kD) protein, specify previously unidentified disulfide bonds between 8 of 27 cysteines in a 1714-residue (200-kD) protein, and correct sequence predictions in two proteins, one with 2153 residues (229 kD).
From the Dark Side to the Bright Side of Drug Addiction
Authors: Everitt Barry J.
Published: October 2006

Neurobiology of Addiction
.
By George F. Koob and Michel Le Moal
. Academic Press (Elsevier), London, 2006. 502 pp. $129, £79.95. ISBN 0-12-419239-4.

The authors offer a survey and synthesis of our current understanding of the neurobiological mechanisms of addiction.
Genetic Variant BDNF (Val66Met) Polymorphism Alters Anxiety-Related Behavior
Authors: Chen Zhe-Yu , Jing Deqiang , Bath Kevin G. , Ieraci Alessandro , Khan Tanvir , Siao Chia-Jen , Herrera Daniel G. , Toth Miklos , Yang Chingwen , McEwen Bruce S. , Hempstead Barbara L. , Lee Francis S.
Published: October 2006

A common single-nucleotide polymorphism in the brain-derived neurotrophic factor (BDNF) gene, a methionine (Met) substitution for valine (Val) at codon 66 (Val66Met), is associated with alterations in brain anatomy and memory, but its relevance to clinical disorders is unclear. We generated a variant BDNF mouse (BDNF
Met/Met
) that reproduces the phenotypic hallmarks in humans with the variant allele. BDNF
Met
was expressed in brain at normal levels, but its secretion from neurons was defective. When placed in stressful settings, BDNF
Met/Met
mice exhibited increased anxiety-related behaviors that were not normalized by the antidepressant, fluoxetine. A variant BDNF may thus play a key role in genetic predispositions to anxiety and depressive disorders.
Out of the Tropics: Evolutionary Dynamics of the Latitudinal Diversity Gradient
Authors: Jablonski David , Roy Kaustuv , Valentine James W.
Published: October 2006

The evolutionary dynamics underlying the latitudinal gradient in biodiversity have been controversial for over a century. Using a spatially explicit approach that incorporates not only origination and extinction but immigration, a global analysis of genera and subgenera of marine bivalves over the past 11 million years supports an “out of the tropics” model, in which taxa preferentially originate in the tropics and expand toward the poles without losing their tropical presence. The tropics are thus both a cradle and a museum of biodversity, contrary to the conceptual dichotomy dominant since 1974; a tropical diversity crisis would thus have profound evolutionary effects at all latitudes.
Activity- and mTOR-Dependent Suppression of Kv1.1 Channel mRNA Translation in Dendrites
Authors: Raab-Graham Kimberly F. , Haddick Patrick C. G. , Jan Yuh Nung , Jan Lily Yeh
Published: October 2006

Mammalian target of rapamycin (mTOR) is implicated in synaptic plasticity and local translation in dendrites. We found that the mTOR inhibitor, rapamycin, increased the Kv1.1 voltage-gated potassium channel protein in hippocampal neurons and promoted Kv1.1 surface expression on dendrites without altering its axonal expression. Moreover, endogenous Kv1.1 mRNA was detected in dendrites. Using Kv1.1 fused to the photoconvertible fluorescence protein Kaede as a reporter for local synthesis, we observed Kv1.1 synthesis in dendrites upon inhibition of mTOR or the
N
-methyl-
d
-aspartate (NMDA) glutamate receptor. Thus, synaptic excitation may cause local suppression of dendritic Kv1 channels by reducing their local synthesis.