bluuebunny/crossref_metadata_2025 huggingface dataset:
Importance of molecular analysis in detecting cervical lymph node metastasis in head and neck squamous cell carcinoma
Authors: Elsheikh Mohamed N. , Rinaldo Alessandra , Hamakawa Hiroyuki , Mahfouz Magdy E. , Rodrigo Juan Pablo , Brennan Joseph , Devaney Kenneth O. , Grandis Jennifer R. , Ferlito Alfio
Published: May 2006

Background.

Because of the impact of nodal status on treatment and survival in squamous cell carcinoma of the head and neck, accurate staging of cervical lymph nodes is critical. This article explores the value of molecular analyses in the detection of cervical lymph node metastasis.

Methods.

A review of the literature was carried out and combined with our own experience regarding the role of molecular analyses in detecting cervical lymph node metastasis.

Results.

Few studies have demonstrated the diagnostic and prognostic relevance of molecular analysis in detecting tumor cells in lymph nodes. Nodal staging was improved by the use of molecular techniques; when compared with histopathologic examination, however, the small sample size of these studies did not allow definitive conclusions.

Conclusions.

Molecular analysis is exquisitely sensitive in detecting very small cancer deposits within lymph nodes. It provides an oncologic basis that may be used to guide therapy and influence outcomes. It should be recommended for diagnostic use in controlled studies of patients without evidence of lymph node metastasis on routine hematoxylin–eosin–stained sections. The clinical significance of these types of metastases, however, must be determined with carefully designed and controlled prospective clinical trials. © 2006 Wiley Periodicals, Inc. Head Neck, 2006
Differential activation and block of peripheral nerve fibers by magnetic fields
Authors: Olree Kenneth S. , Horch Kenneth W.
Published: May 2006

The ability to noninvasively and reversibly block conduction in peripheral nerves would have several clinical applications. As an initial step in this direction, we investigated the possibility of magnetically generating and differentially blocking activity in mammalian peripheral nerve fibers in vitro. Compound action potentials at each end of individual explanted phrenic nerves were recorded in response to currents induced at the midpoint of the nerve with an externally placed magnetic coil. Current in the coil was then reversed and the recordings repeated. In all cases, the area under the compound action potential on the virtual anode side of the magnetic stimulus was reduced (mean of 18.2 ± 8.8%) in comparison to the area on the virtual cathode side. This indicates that peripheral nerve activity can be differentially induced by magnetic stimulation. Extension of this effect to the point of generating unidirectional action potentials in vivo may prove clinically useful in a number of contexts, such as reducing contractures secondary to spasticity and generating magnetically induced anesthesia in limbs. Further investigations of this effect seem warranted. Muscle Nerve, 2006
TEM analyses of wurtzite InGaN islands grown by MOVPE and MBE
Authors: Pretorius A. , Yamaguchi T. , Kübel C. , Kröger R. , Hommel D. , Rosenauer A.
Published: May 2006

The microstructure and composition of InGaN islands is analysed by transmission electron microscopy. Island samples were grown by metalorganic vapour phase epitaxy and molecular beam epitaxy, exhibiting different microstructures. Differences of the In concentration in the islands are discussed with respect to the observed relaxation of the islands. Furthermore the capping of molecular beam epitaxially grown island samples with GaN is investigated, showing a pronounced dissolution already at a nominal cap layer thickness of 2 nm. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carrier lifetime and diffusion in GaN epilayers grown by MEMOCVDTM
Authors: Tamulaitis G. , Mickevičius J. , Shur M. S. , Qhalid Fareed R. S. , Zhang J. P. , Gaska R.
Published: May 2006

Carrier lifetimes in GaN epilayers are studied by using time‐resolved photoluminescence (TRPL) and light‐induced transient grating (LITG) techniques. It is shown that the photoluminescence decay can be described by two coupled exponents with characteristic decay times equal to the carrier lifetime and to the half of the carrier lifetime. Both carrier lifetime and diffusion coefficient have been estimated by using LITG technique. For samples with lifetimes shorter than ∼1 ns, the epilayers with lower mobilities have longer lifetimes so that the diffusion length is nearly constant. This correlation is due to the nonradiative recombination of the carriers at defects probably related to dislocations and having approximately the same density in different samples under study. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical characterization of GaN microcavity fabricated by wet etching
Authors: Lu C.‐Y. , Wang S.‐L. , Wu H.‐M. , Peng L.‐H.
Published: May 2006

We report a novel technique to fabricate gallium nitride (GaN) microcavities by combining the methods of photo‐enhanced wet chemical oxidation and crystallographic etching. Such GaN microcavities exhibit mirror‐like vertical facets composing of {1100}GaN and various gemoetry of hexagonal, trigonal and cylindrical shapes. The emission spectra of the GaN micro‐cavities are found in resonance with the whispering gallery (WG) modes when pumped with a 266 nm Nd:YAG laser. The signatures of GaN microcavities were further characterized by an increase of the WG mode spacing with the reduced device size and suppression of the side mode emission intensity with pump intensity. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparative optical studies on violet InGaN quantum well laser diode structures grown on sapphire and GaN substrates
Authors: Hwang J. S. , Choi J. W. , Gokarna A. , Cho Y. H. , Son J. K. , Lee S. N. , Sakong T. , Paek H. S. , Nam O. H. , Park Y.
Published: May 2006

We have investigated the optical properties of violet InxGa1–xN/InyGa1–yN multiple quantum well laser diode structures grown on sapphire and GaN substrates by means of photoluminescence (PL), PL excitation, and time‐resolved PL spectroscopy. The PL result shows a red‐shift behavior of the emissions from GaN capping layer and the 10‐nm‐thick InyGa1–yN barriers on the GaN substrate due to the reduction of residual compressive strain. On the other hand, we have observed a blue shift of the PL emission from the 4‐nm‐thick InxGa1–xN wells for the samples grown on GaN substrates. This can be attributed to the reduction of strain‐induced piezoelectric field between InxGa1–xN wells and InyGa1–yN barriers due to the direct growth on GaN substrates, which is confirmed by a reduction of the Stokes‐like shift between InxGa1–xN PL and its absorption edge and a decrease in overall decay lifetimes for the samples grown on GaN substrates. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoelectrochemical sidewall etching enhances light output power in GaN‐based light emitting diodes
Authors: Lin C. F. , Dai J. J. , Jiang R. H. , Zheng J. H. , Yang Z. J. , Yu C. C. , Lee W. C.
Published: May 2006

InGaN/GaN multi‐quantum‐well light‐emitting diodes (MQW LEDs) are grown through a metal‐organic chemical vapor deposition (MOCVD) System. The fabricated GaN‐based LED wafers are treated with a photoelectrochemical (PEC) wet etching process using a Hg lamp illumination and KOH solution. The band‐gap selected wet etching process of InGaN/GaN MQW layer was observed from the mesa sidewall between the p‐type and n‐type GaN interface which has the 4.2 (m/hr lateral etching rate. The emission wavelength of the etching treated LED and standard LED were located at 458 nm. The light output power of the PEC etching LED had 2.04, 5.94, and 1.73 times enhancement measured from the from‐side, lateral‐direction, and back‐side compared with the standard ones. The light output power have stronger enhancement caused by forming the triangle‐shaped air holes located at the active layer region, grain‐like roughening surface and nano‐scale triangle pits on the mesa sidewall. The light scattering by this roughening sidewall was increased to enhance the light extraction efficiency. This PEC sidewall etching process is suitable for high power Nitride‐based LEDs lighting applications. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study on influence of atomic hydrogen irradiation on growth and property of N‐polarity InN
Authors: Che Song‐Bek , Akasaka Koichiro , Ishitani Yoshihiro , Yoshikawa Akihiko
Published: May 2006

Epitaxial growth of N‐polarity InN films under atomic‐hydrogen irradiation was systematically investigated. It was found that any difference could not be observed in electron concentrations of InN films with and without the atomic‐H irradiation, where typical residual carrier concentrations were from 3 to 5×1018 cm–3. These results suggest that the atomic H may not be an origin of residual donors at least in the InN films with carrier concentrations of 3‐5×1018 cm–3. On the other hand, the atomic‐H irradiation was effective in improving surface morphology of the InN films, which suggested an effect of surfactant on InN epitaxy. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication and characterization of InGaN resonant‐cavity light‐emitting diodes on silicon substrates
Authors: Huang Shih‐Yung , Horng Ray‐Hua , Wang Wei‐Kai , Wuu Don‐Sing
Published: May 2006

GaN‐based resonant‐cavity light‐emitting diodes (RCLEDs) have been fabricated on Si substrates by a combination of laser lift‐off and wafer bonding techniques. The RCLED structure consisted of an InGaN/GaN multiple‐quantum‐well active layer between the top (5‐pairs) and bottom (7.5‐pairs) dielectric TiO2/SiO2 distributed Bragg reflector (DBR) with an optical reflectance of 85 and 99.9%, respectively. The cavity mode of the RCLED shows a linewidth of 5.5 nm at a main emission peak at 525 nm. The emission full width at half maximum can decrease from 48 to 35 nm, indicating the effect of the DBR microcavity. The quality factor for this resonant cavity structure was estimated to be approximately 100. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of stacking on optical characteristics of GaN/AlN self‐organized quantum dots
Authors: Kwon B. J. , Hwang J. S. , Kwack H. S. , Cho Y. H. , Gogneau N. , Daudin B. , Dang Le Si
Published: May 2006

The effect of stacking on the optical properties of self‐organized GaN/AlN quantum dots (QDs) grown by plasma‐assisted molecular beam epitaxy was investigated by photoluminescence (PL), PL excitation (PLE), and cathodoluminescence (CL) spectroscopic techniques. With an increase in the number of the GaN QDs stacking layer, we observed a red shift in the main QD PL peaks. A Stokes‐like shift was observed between PL emission and PLE absorption edge for all the samples. From the depth‐resolved CL of a 200‐period GaN QD sample, we observed that the main QD CL emission peak energy position does not change much, while the higher‐energy side CL peak around ∼3.7 eV shows a variation of its peak position with the accelerating voltage probably due to the change in either distribution of QD size/shape or wetting layer properties during the growth of multiple stacking of GaN QDs. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wet‐Milling of Grain Sorghum of Varying Seed Size Without Steeping
Authors: Xie Xueju J. , Liang Yun Teh S. , Seib Paul A. , Tuinstra Mitchell R.
Published: May 2006

Experimental lines of hybrid grain sorghums were produced with thousand‐kernel‐weights (TKW) varying between 23.1–44.9 g. The proportion of germ in the normal‐seeded hybrids with TKW 23–27 g was ∼ 9.9–10.2% of dry kernel weight, whereas that in the large‐seeded hybrids with TKW 37–45 g was ∼ 10.8–11.2%. Starch in grain decreased ∼ 4% as kernel weight increased which was offset by an increase in protein level. Wet‐milling of the grain was done without steeping after an initial coarse‐grinding step in two parts of water with 0.3% sodium bisulfite. Three of four samples of large‐seeded and soft‐textured grain sorghums gave 77–82% recovery of starch with 0.5–0.7% protein, while one gave 59% recovery and 0.6% protein. The starches had < 0.5% damaged starch, gave no rancid off‐odor after storing 26 months at 25°C in a sealed glass container, and had lightness (L*) values of 93.1–93.7 vs. 95.2 for a commercial corn starch. Their pasting curves were similar to that of commercial corn starch. The bran/germ/endosperm fraction obtained by limited wet‐milling of one large‐seeded hybrid was separated by flotation to recover one‐half the germ in 98% purity as estimated by fat content.
Effects of Half‐dose Aprotinin in Off‐pump Coronary Artery Bypass Grafting
Authors: Wei Minxin , Jian Kaitao , Guo Zhipeng , Li Peijun , Han Jiange , Cai Zhong , Tarkka Matti
Published: May 2006

Objective

The effects of half‐dose aprotinin in off‐pump coronary artery bypass (OPCAB) surgery have not yet been described. The present prospective study was designed to investigate its effects in OPCAB.

Methods

Seventy‐six patients were randomized into two groups, receiving aprotinin (1 × 106 Kallikrein‐inactivating units [KIU] loading dose before surgery and 5 × 105 KIU/h during surgery, gross dose: 2.5 × 106 KIU, n = 36) and saline solution (control, n = 40) respectively. Perioperative blood samples were collected. Hematologic and hemostatic parameters including platelet adhesion rate, D‐dimer, and fibrinopeptide‐A (FPA) were analyzed. Perioperative CKMB release was measured. Volume of blood loss, blood transfusion, and other clinical data were recorded throughout the perioperative period.

Results

Postoperative blood loss was significantly reduced in patients treated with aprotinin (2 hours; median [25th–75th]: aprotinin: 90.0 [70.0–125.0] ml, control: 145.0 [70.0–180.0] ml, P < 0.05; 6 hours: aprotinin: 150.0 [100.0–220.0] ml, control: 225.0 [200.0–347.5.0] ml, P < 0.01; 24 hours: aprotinin: 370.0 [220.0–510.0] ml, control: 655.0 [500.0–920.0] ml, P < 0.01). The number of patients receiving blood transfusion in each group was similar. Levels of D‐dimer rose significantly after surgery, and were significantly lower in the aprotinin group than in the controls (end of surgery, aprotinin, 0.4 [0.2–0.5] mg/l versus controls, 1.4 [0.8–2.3] mg/l; 2 hours, aprotinin, 0.3 [0.2–0.4] mg/l versus controls, 0.9 [0.5–1.4] mg/l; 6 hours, aprotinin, 0.3 [0.2–0.5] mg/l versus controls, 0.6 [0.4–0.9] mg/l; 24 hours, aprotinin, 0.3 [0.2–0.4] mg/l versus controls, 0.5 [0.4–0.9] mg/l; ANOVA for repeated measures, P < 0.01). Platelet adhesion rate and FPA levels remained at baseline levels after the operation in the two groups. Early clinical outcomes were similar in the groups. Levels of CKMB were significantly lower in the aprotinin group than in the controls (6 hours after surgery, aprotinin, 10.0 [8.0–16.0] U/l versus controls, 15.5 [11.0–20.3] U/l; 12 hours, aprotinin, 13.5 [10.0–20.0] U/l versus controls, 19.0 [12.8–24.3] U/l; 24 hours, aprotinin, 19.0 [13.5–33.8] U/l versus controls, 25.0 [15.0–43.3] U/l; 72 hours, aprotinin, 13.0 [8.0–18.0] U/l versus controls, 16.0 [10.0–29.0] U/l; ANOVA for repeated measures, P = 0.018).

Conclusion

The results indicated that half‐dose aprotinin limits fibrinolysis and myocardial injury, and reduces blood loss after OPCAB surgery.
Radical Subtotal Pancreatic Resection, Including Splenectomy, Is an Effective One‐off Treatment for Infected Pancreatic Necrosis
Authors: Davies Justin , Stojkovic Stevan G. , Duffy David , Alexander David J.
Published: May 2006

Background

Pancreatic resection for severe acute necrotizing pancreatitis has been associated with prohibitive mortality rates and has been hence replaced by piecemeal debridement, either by the open or the laparoscopic technique. We report the results of deliberate subtotal pancreatectomy with splenectomy for infected pancreatic necrosis.

Materials and methods

Six‐year prospective audit of patients treated by a single surgeon, with an interest in pancreatic disease, within a Low Volume Hospital (LVH) setting. Results are presented as median (IQR).

Results

During the study period 18 patients (9 males) with complicated severe acute pancreatitis underwent radical pancreatic resection. The median age was 61 years (range 36–69). The median time to operation after presentation was 27 days (range 2–74). Microbiological culture confirmed infection in 14 (78%) patients. Three patients (17%) died within 30 days of operation. Twelve of the 15 survivors (80%) underwent a single operative procedure. Three patients required a further laparotomy, of whom 2 required colectomy for ischemia. Median hospital and ICU stays were 43 (range 30–57) and 5 (range 4–6) days respectively. Six patients (40% of survivors) developed an infection of the left half of the chevron incision; however, all wounds were fully healed within 3 months. Long‐term follow‐up of survivors (n = 14) revealed 8 (57%) to need at least occasional pancreatic enzyme supplementation and 5 (36%) to have diabetes mellitus. Two patients (14%) developed an incisional hernia.

Conclusions

Radical resection of pancreas and spleen, combined with postoperative irrigation, was associated with comparatively low rates of morbidity and mortality for patients with infected pancreatic necrosis in a LVH setting.
A bifid intra-tympanic facial nerve in association with a normal stapes
Authors: Ahmed J , Chatrath P , Harcourt J
Published: May 2006

A rare facial nerve anomaly was incidentally discovered whilst performing a tympanoplasty and ossicular reconstruction on a patient with an acquired unilateral conductive hearing loss. The nerve was seen to bifurcate and straddle a normal stapes superstructure as it ran posteriorly through the middle ear, a unique and as yet unreported combination. This case highlights the importance of vigilance regarding facial nerve anatomical variations encountered during middle-ear surgery thus avoiding inadvertent damage. The purported embryological mechanism responsible for such anomalies of the intra-tympanic facial nerve is discussed.
Silencing the snorers: no gain without pain?
Authors: Wilson J A , Lester S E , Gibson G J , Anari S , Steele J G , Steen I N , McCracken G I
Published: May 2006

Objective: To compare the estimated effects of conservative surgery to those of a mandibular advancement splint (MAS) in the treatment of habitual snoring.

Method: Prospective, observational, non-randomized cohort study.

Results: Adequate follow-up data were available for 88 participants (23 following coblation, 65 after provision of an MAS). The mean reduction in snoring symptoms inventory (SSI) score for the 23 subjects undergoing coblation was 9.83 (± standard deviation 11.43). Reported pain duration was greatest with uvula amputation, but uvula coblation did not always adequately reduce its bulk. Of the 65 MAS patients, 39 (60 per cent) used the device regularly, with a mean fall in SSI of 12 (±16.4, p = 0.001). Approximately one in four patients in both groups achieved a significant fall in SSI (>15 points), and the measured effect sizes were close to 0.75 for both treatments.

Conclusions: Mandibular advancement splints and coblation have similar efficacies. However, their efficacy does not match that of radical surgery.
Review of: Proliferation of estrogen receptor-alpha-positive mammary epithelial cells is restrained by transforming growth factor-beta1 in adult mice
Authors: Kalirai H. , Clarke R. B.
Published: May 2006

Citation of original article:

K. B. Ewan, H. A. Oketch-Rabah, S. A. Ravani, G. Shyamala, H. L. Moses, M. H. Barcellos-Hoff. Proliferation of estrogen receptor-alpha-positive mammary epithelial cells is restrained by transforming growth factor-beta1 in adult mice.American Journal of Pathology2005;167(2): 409–17.

Abstract of the original article:

Transforming growth factor (TGF)-beta1 is a potent inhibitor of mammary epithelial proliferation. In human breast, estrogen receptor (ER)-alpha cells rarely co-localize with markers of proliferation, but their increased frequency correlates with breast cancer risk. To determine whether TGF-beta1 is necessary for the quiescence of ER-alpha-positive populations, we examined mouse mammary epithelial glands at estrus. Approximately, 35% of epithelial cells showed TGF-beta1 activation, which co-localized with nuclear receptor-phosphorylated Smad 2/3, indicating that TGF-beta signaling is autocrine. Nuclear Smad co-localized with nuclear ER-alpha. To test whether TGF-beta inhibits proliferation, we examined genetically engineered mice with different levels of TGF-beta1. ER-alpha co-localization with markers of proliferation (i.e., Ki-67 or bromodeoxyuridine) at estrus was significantly increased in the mammary glands of TGF-beta1 C57/bl/129SV heterozygote mice. This relationship was maintained after pregnancy but was absent at puberty. Conversely, mammary epithelial expression of constitutively active TGF-beta1 via the MMTV promoter suppressed proliferation of ER-alpha-positive cells. Thus, TGF-beta1 activation functionally restrains ER-alpha-positive cells from proliferating in adult mammary gland. Accordingly, we propose that TGF-beta1 dysregulation may promote proliferation of ER-alpha-positive cells associated with breast cancer risk in humans.
Capacitevely loaded bowtie antenna for ultrawideband impulse radio
Authors: Yarovoy Alexander G. , Pugliese Roberto
Published: May 2006

The impact of an azimuthal slot in the antenna flair on the performance of a bowtie antenna has been analyzed. It has been shown that the slot is equivalent to resistance‐capacitance loading. The resistance of the slot is physically caused by radiation of electromagnetic energy from the slot. Equivalent resistance and capacitance of the slot have been analyzed against geometrical parameters and frequency. The azimuthal slot has been used to improve the bowtie performance and to optimize this antenna for an ultrawideband impulse radio system under development. After optimization, the antenna exhibits a better performance than the conventional bowtie in terms of efficiency, late‐time ringing, and matching to the generator/receiver. The performance of the optimized antenna has been verified experimentally; good agreement between theory and experiment has been observed.
Vegetation dynamics amplifies precessional forcing
Authors: Claussen Martin , Fohlmeister Jens , Ganopolski Andrey , Brovkin Victor
Published: May 2006

The astronomical theory of climate variations predicts that the climatic precession which changes the seasonal distance between Earth and Sun does not affect the annual mean irradiation at any given latitude. However, previous modeling studies suggest that during interglacials, the interaction between atmosphere, vegetation and ocean can transform the seasonal forcing by precession into an annual mean global signal. Here, we show that this result can be generalized. A distinct precessional signal emerges in a climate system model over many precessional cycles. While neither the atmosphere‐ocean nor the atmosphere‐vegetation model are able to produce a large amplitude of global temperature in the precessional band, only the mutual amplification of biogeophysical feedback and sea ice‐ albedo feedback allows a strong amplification of the precessional signal.
Detailed diagnosis of a double-shell collision under realistic implosion conditions
Authors: Kyrala G. A. , Gunderson M. A. , Delamater N. D. , Haynes D. A. , Wilson D. C. , Guzik J. A. , Klare K. A.
Published: May 2006

Double-shell implosions provide a noncryogenic path to inertial confinement fusion. In the double-shell target, the energy is absorbed in an outer shell that is accelerated inward and collides with an inner shell that implodes against the deuterium fuel. Symmetric collision of the shells requires that the shells be illuminated and built symmetrically. In reality, the targets are complicated and the construction is not symmetric, due to the seam that our current assembly method requires. Using the Omega laser [R. T. Boehly et al., Opt. Comm. 133, 495 (1997)], an illumination strategy was designed that uses 40 beams in an offset geometry, leaving 20 beams to perform radiography from two different directions. This places a significant nonsymmetric illumination challenge that may not exist in final targets shot on the National Ignition Facility. This paper presents a measurement of the time history of a collision of two shells in a double-shell capsule, briefly reviews the illumination geometry, gives the results of the measurements of the trajectory and symmetry of the outer and inner shells, shows the effect of a seam on the inner shell implosion, and compares the results with calculations. The measurement of such a collision in a spherical geometry is of great interest to the study of double-shell implosions as well as code validation.
Time-resolved measurements of the density fluctuations in ion phase space
Authors: Diallo Ahmed , Skiff Frederick
Published: May 2006

A two-point correlation function measurement of the ion density fluctuations is presented. Using two laser-induced fluorescence (LIF) detection systems, the density fluctuation is resolved in time, ion parallel velocity, and space (along the magnetic field). The measurements reveal two components of the density fluctuations, one of which is explained by fluid theory. The other component is ion-velocity-dependent and is newly identified. In addition to the density fluctuation measurements, a velocity-resolved estimate of the fluctuation-induced transport flux using correlations between a Langmuir probe and LIF is reported.
New opportunities for plasma science in nonequilibrium, low-temperature plasmas confined to microcavities: There’s plenty of room at the bottom
Authors: Eden J. G. , Park S.-J.
Published: May 2006

Nonequilibrium, low-temperature plasmas have, in just the past few years, been confined to microcavities with characteristic dimensions (d) as small as 10μm. Plasma science has thus entered a new realm of parameter space in which d is on the order of tens of debye lengths and the plasma frequency ωp∕2π is approaching 1 THz. In this previously unexplored region, plasmas display intriguing characteristics, including the loss of quasineutrality and the ability to operate continuously at atmospheric pressure and beyond. This article will briefly describe the fabrication and behavior of microcavity plasma devices realized by the adaptation of microfabrication techniques, and device structures inspired by nanotechnology. Exciting opportunities for plasma science are within reach and a few of the implications of driving d to 1μm and into the nanometer domain are discussed.
Contribution of the asymmetric stretch, ν3B1, to the fundamental Raman spectrum of water
Authors: Walrafen George E.
Published: May 2006

The OD-stretching overtone from liquid D2O, 2ν, and the fundamental OD stretch from dilute HDO, both display high-frequency depolarization ratio minima, but the fundamental OD stretch from neat D2O displays a maximum, at the equivalent position. The ρL minima arises from the decreased depolarization ratio produced by the absence of B1 modes. The fundamentals of HDO are of A species, and the 2ν overtone of D2O only involves A1 species, e.g., 2ν3B1 has A1 species via B1×B1=A1. A and A1 modes display small ρL values which produce minima in ρL near 2665cm−1 for HDO, and near 5250cm−1 for the D2O overtone. These minima give way to a depolarization ratio maximum when the depolarized, ρL=3∕4, ν3B1 fundamental, makes its appearance in D2O at 2650cm−1. Fundamental and overtone depolarization ratios were used to determine the ν3B1 contribution to the depolarization ratio of the fundamental OD stretch; a value of ≈28% resulted at 2655cm−1. Liquid H2O displays completely analogous features; a value of ≈20% resulted for it at 3660cm−1. Nonhydrogen-bonded ν3B1, and more strongly hydrogen-bonded ν3B1, modes are also indicated for D2O and H2O. A rigorous test of the current results can be accomplished by measuring the depolarization ratio of the extraordinarily weak second Raman overtone, 3ν, recently detected for D2O.
Network reorganization driven by temporal interdependence of its elements
Authors: Waddell Jack , Zochowski Michal
Published: May 2006

We employ an adaptive parameter control technique based on detection of phase/lag synchrony between the elements of the system to dynamically modify the structure of a network of nonidentical, coupled Rössler oscillators. Two processes are simulated: adaptation, under which the initially different properties of the units converge, and rewiring, in which clusters of interconnected elements are formed based on the temporal correlations. We show how those processes lead to different network structures and investigate their optimal characteristics from the point of view of resulting network properties.
A validation of the p-SLLOD equations of motion for homogeneous steady-state flows
Authors: Edwards B. J. , Baig C. , Keffer D. J.
Published: May 2006

A validation of the p-SLLOD equations of motion for nonequilibrium molecular dynamics simulation under homogeneous steady-state flow is presented. We demonstrate that these equations generate the correct center-of-mass trajectory of the system, are completely compatible with (and derivable from) Hamiltonian dynamics, satisfy an appropriate energy balance, and require no fictitious external force to generate the required homogeneous flow. It is also shown that no rigorous derivation of the SLLOD equations exists to date.
Scaling and universality of the complexity of analog computation
Authors: Avizrats Yaniv , Feinberg Joshua , Fishman Shmuel
Published: May 2006

We apply a probabilistic approach to study the computational complexity of analog computers which solve linear programming problems. We numerically analyze various ensembles of linear programming problems and obtain, for each of these ensembles, the probability distribution functions of certain quantities which measure the computational complexity, known as the convergence rate, the barrier and the computation time. We find that in the limit of very large problems these probability distributions are universal scaling functions. In other words, the probability distribution function for each of these three quantities becomes, in the limit of large problem size, a function of a single scaling variable, which is a certain composition of the quantity in question and the size of the system. Moreover, various ensembles studied seem to lead essentially to the same scaling functions, which depend only on the variance of the ensemble. These results extend analytical and numerical results obtained recently for the Gaussian ensemble, and support the conjecture that these scaling functions are universal.
Subattoampere current induced by single ions in silicon oxide layers of nonvolatile memory cells
Authors: Cellere G. , Paccagnella A. , Larcher L. , Visconti A. , Bonanomi M.
Published: May 2006

A single ion impinging on a thin silicon dioxide layer generates a number of electron/hole pairs proportional to its linear energy transfer coefficient. Defects generated by recombination can act as a conductive path for electrons that cross the oxide barrier, thanks to a multitrap-assisted mechanism. We present data on the dependence of this phenomenon on the oxide thickness by using floating gate memory arrays. The tiny number of excess electrons stored in these devices allows for extremely high sensitivity, impossible with any direct measurement of oxide leakage current. Results are of particular interest for next generation devices.
A new paradigm for plasma transport and zonal flows
Authors: Sen A. K. , Sokolov V. , Wei X.
Published: May 2006

Most tokamak experimental results indicate dependence of the ion thermal conductivity on the isotopic mass close to χ⊥∼mi−0.5, i.e., inverse gyro-Bohm. This is in stark contradiction to most present theoretical models predicting Bohm (mi0) or gyro-Bohm (mi0.5) scaling. A basic physics isotopic scaling experiment [V. Sokolov and A. K. Sen, Phys. Rev. Lett. 89, 095001 (2002)] on the anomalous ion thermal conduction due to ion temperature gradient (ITG) instabilities in two different gases (hydrogen and deuterium) closely confirms the tokamak results. Another series of experiments designed to explore the physics basis of this scaling appears to lead to a new model for this scaling based on 3-wave coupling of two ITG radial harmonics and an IA wave. The resulting isotopic scaling of transport is ∼mi−0.5 dictated primarily by the IA damping. This basic physics may be extrapolated to tokamaks resolving the paradox [V. Sokolov and A. K. Sen, Phys. Rev. Lett. 92, 165002 (2004)]. Last, the much discussed theoretical role of zonal flows in transport regulation is critically examined by another set of experiments. A novel diagnostic has been developed on the basis of the observation that the effect of zonal flow can be seen in the FM modulation (at zonal flow frequency) of the carrier frequency of the large equilibrium Doppler shift frequency of ITG modes both in tokamaks and in the Columbia Linear Machine [V. Sokolov, X. Wei, and A. K.Sen, APS DPP meeting, Savannah (2004)]. The present results indicate zonal flow levels close to the theoretical prediction, but its shear is much lower than that predicted by theory for transport regulation.
The poloidal distribution of type-III edge localized modes in the Mega-Ampère spherical tokamak (MAST)
Authors: Antar G. Y.
Published: May 2006

This article describes the poloidal plasma particle distribution of type-III edge localized modes (ELMs) in the Mega-Ampère spherical tokamak [R.-J. Akers et al., Phys. Plasmas 9, 3919 (2002)]. A fast imaging camera with 10μs exposure time is used to record the Dα light coming from the entire poloidal cross section. Furthermore, three sets of probes, triggered at the same time, acquired at 1MHz, and located at different poloidal, radial, and toroidal locations in the tokamak are used. ELMs are observed to affect the Dα emission throughout the low-field scrape-off layer; on the high-field side, however, this effect is found to be small. The results obtained by imaging agree with the pointwise measurements using Langmuir probes. The radial propagation is shown to occur at a speed of 250m∕s, whereas the toroidal convection from the top to the bottom of the plasma is shown to be consistent with a transport at the local sound speed. Strong correlation amplitudes are reported among the probes that are poloidally and toroidally separated by several meters. The study of the cross-correlation coefficients as a function of the frequency indicates that this correlation is caused by the low-frequency component of the signal and that the high-frequency part is not correlated. Consequently, the filamentary structures are interpreted as caused by the onset of turbulence during an ELM and do not constitute the ELM itself.
Investigation of the Nicole model
Authors: Adam C. , Sánchez-Guillén J. , Vázquez R. A. , Wereszczyński A.
Published: May 2006

We study soliton solutions of the Nicole model—a non-linear four-dimensional field theory consisting of the CP1 Lagrangian density to the non-integer power 32—using an ansatz within toroidal coordinates, which is indicated by the conformal symmetry of the static equations of motion. We calculate the soliton energies numerically and find that they grow linearly with the topological charge (Hopf index). Further we prove this behavior to hold exactly for the ansatz. On the other hand, for the full three-dimensional system without symmetry reduction we prove a sub-linear upper bound, analogously to the case of the Faddeev–Niemi model. It follows that symmetric solitons cannot be true minimizers of the energy for sufficiently large Hopf index, again in analogy to the Faddeev–Niemi model.
Switching spin valves using rf currents
Authors: Rivkin K. , Ketterson J. B.
Published: May 2006

We show that magnetization reversal in spin-injection devices can be significantly faster when using a chirped rf current, rather than a dc, pulse. Although one can use a simple sinusoidal rf pulse, an optimized series of alternating, equal-amplitude, pulses of varying width (a digitized approximation to a chirped rf pulse) produces more efficient switching.
Electron emission mechanism of diamond characterized using combined x-ray photoelectron spectroscopy/ultraviolet photoelectron spectroscopy/field emission spectroscopy system
Authors: Yamaguchi Hisato , Yamada Takatoshi , Kudo Masato , Takakuwa Yuji , Okano Ken
Published: May 2006

Clarification on electron emission mechanism of diamond is one essential approach to realize the clear vision of vacuum nanoelectronics. Electric field of less than 5V∕μm is enough to extract electrons from diamond, whereas field of one to two orders of magnitude higher is needed to extract electrons from conventional metal emitter tips. Diamond has various advantages as an electron emitter in addition to the low-threshold voltage, such as negative electron affinity and high thermal conductivity. The difficulty in clarification of electron emission mechanism is the factor preventing diamond from being used in a practical way. In this study, combined spectroscopy of x-ray photoelectron spectroscopy/ultraviolet photoelectron spectroscopy/field emission spectroscopy was performed to characterize the electron emission mechanism of diamond. The results indicated the first successful observation of applied voltage dependence on the origin of field-emitted electrons.
Fluid viscosity determination by means of uncalibrated atomic force microscopy cantilevers
Authors: Papi Massimiliano , Arcovito Giuseppe , De Spirito Marco , Vassalli Massimo , Tiribilli Bruno
Published: May 2006

In this letter it has been proved that the vibrating resonance frequency of an atomic force microscope cantilever is strictly characterized by its thickness (α), while its width/thickness ratio (β) appears to be a less sensitive parameter that can be approximated to a constant. We therefore propose a data analysis method that, by accounting for a constant β, allows for the determination of the value of α and consequently to calculate η. This method of monitoring viscosity has the advantage of requiring short measurement times on very small sample volumes, thereby avoiding laborious, time-consuming cantilever calibration.
Differential equation model of an Alfvén wave maser
Authors: Morales G. J. , Maggs J. E.
Published: May 2006

A mathematical model describing the operation of an Alfvén wave maser in a laboratory environment is constructed from a continuous differential equation. The model incorporates the essential features of maser operation, namely, a resonator with a semitransparent boundary, a unidirectional amplification region, and a nonuniform magnetic field that provides frequency filtering. The spectral features and the parameter scaling predicted by the model are in agreement with laboratory measurements of an Alfvén wave maser [J. E. Maggs and G. J. Morales, Phys. Rev Lett. 91, 035004 (2003)]. The model provides a useful tool to explore a variety of operational scenarios for users of this novel wave source, including studies of Alfvénic interactions of relevance to space and fusion plasmas.
Analytical nonlinear theory of the orotron
Authors: Nusinovich Gregory S.
Published: May 2006

The orotron is a device in which a sheet electron beam excites electromagnetic (EM) oscillations in an open resonator formed by a concave mirror and a periodic grating plate. The first spatial harmonic of a field near the grating has phase velocity close to electron velocity; therefore electrons streaming over the grating surface produce Cherenkov or Smith-Purcell radiation. The orotrons can be configured for producing coherent radiation at short millimeter and submillimeter wavelengths (up to the terahertz range). Typically the amplitude of the EM field in the orotron is rather small. Therefore, for extracting an appreciable part of electron kinetic energy, it is necessary to realize synchronous interaction between electrons and a slow wave at long enough distances. This peculiarity of the orotron operation makes it possible to develop an analytical nonlinear theory of the orotron. Such a theory showing how to optimize the choice of the interaction length and the ratio between ohmic and diffractive losses is developed in the present paper. The theoretical treatment is accompanied with consideration of practical effects limiting the orotron efficiency.
Interfacial reactions in a HfO2∕TiN/poly-Si gate stack
Authors: MacKenzie M. , Craven A. J. , McComb D. W. , De Gendt S.
Published: May 2006

Interface reactions are investigated in a Si(100)∕SiO2∕HfO2∕TiN/poly-Si gate stack using electron-energy-loss spectroscopy. The electron-energy-loss near-edge fine structure on the core edges shows evidence of interface reactions having occurred between the TiN metal gate and surrounding layers. A Si(O,N) phase is observed at the TiN/poly-Si interface.
Graphitic onions as reaction cells on the nanoscale
Authors: Sun L. , Banhart F.
Published: May 2006

Multishell fullerene clusters (carbon onions) encapsulating iron crystals of a few nanometers in size are subjected to intense electron irradiation at high temperature in an electron microscope. A reaction between graphite and iron, leading to the formation of iron carbide (cementite) in the core of the clusters, is observed in situ. The reaction in these spherical nanoencapsulates is explained by the occurrence of high pressure, mobile carbon interstitial atoms, and the irradiation-induced lowering of the kinetic barrier. Thus, carbon onions can be used as high-pressure cells for inducing a chemical reaction in nanometer-sized particles.
Molecular beam epitaxial growth window for high-quality (Ga,In)(N,As) quantum wells for long wavelength emission
Authors: Ishikawa Fumitaro , Höricke Michael , Jahn Uwe , Trampert Achim , Ploog Klaus H.
Published: May 2006

We grow high-quality (Ga,In)(N,As) quantum wells containing 36% In and 4.5% N by molecular beam epitaxy, with a low As pressure and low substrate temperature growth concept. A V/III beam equivalent pressure ratio of 5 and a substrate temperature of 375°C lead to highly regular ten-period multiple quantum well structures having abrupt interfaces and smooth surfaces. By varying the quantum well width from 4to8nm, we observe 1.34–1.6μm emission of narrow linewidth (⩽50meV) at room temperature after annealing. The large conduction band offset of 410meV estimated from calculations is beneficial for a material system considered for high temperature laser operation.
Blue luminescence from electron-doped SrTiO3
Authors: Kan D. , Kanda R. , Kanemitsu Y. , Shimakawa Y. , Takano M. , Terashima T. , Ishizumi A.
Published: May 2006

Blue-light emissions from electron-doped SrTiO3 single crystals at room temperature were observed. Substituting La3+ for Sr2+ and Nb5+ for Ti4+ in SrTiO3 provides electron carriers in Ti 3d conduction bands; these carriers are responsible for the room-temperature blue-light emission. This blue-light emission is essentially the same as that observed in Ar+-irradiated oxygen-deficient SrTiO3. This blue luminescence is independent of the defect type. The chemical substitution of La3+ for Sr2+ changes the temperature of the structural phase transition from cubic to tetragonal symmetry. The relation between the photoluminescence properties and the structural phase transition is also discussed.
External cavity multiwavelength semiconductor hybrid mode-locked laser intracavity gain dynamics
Authors: Archundia Luis C. , Delfyett Peter J.
Published: May 2006

The intracavity gain dynamics of an external cavity semiconductor hybrid mode-locked laser is measured under multiwavelength operation. The results show a temporal skew between pulses corresponding to different wavelength channels. A measurement of the temporal evolution of the gain reveals a slow gain depletion, avoiding carrier heating and carrier cooling, and decreasing self-phase modulation effects and gain competition between wavelength channels, making multiwavelength operation possible.
Physical insight into boron activation and redistribution during annealing after low-temperature solid phase epitaxial regrowth
Authors: Aboy Maria , Pelaz Lourdes , López Pedro , Marqués Luis A. , Duffy R. , Venezia V. C.
Published: May 2006

Kinetic Monte Carlo simulations of B diffusion and activation in preamorphized Si during annealing after solid phase epitaxial regrowth have been used to provide insight into the mechanisms that drive these phenomena. Simulations show that the presence of an initially high active B concentration along with a Si interstitial supersaturation set by end of range defects leads to simultaneous B deactivation and uphill diffusion through the capture of mobile interstitial B in the high concentration region during subsequent anneal treatments. Once the Si interstitial supersaturation decays close to equilibrium values, B clusters dissolve and emitted B diffuses downhill, following the B concentration gradient. The active B concentration at the minimum state of activation becomes higher as the annealing temperature increases as a consequence of a faster increase of the B cluster dissolution rate compared with the formation rate.
Confining light in two-dimensional slab photonic crystal waveguides with metal plates
Authors: Wang Bing , Wang Guo Ping
Published: May 2006

Light cannot be strongly confined in two-dimensional (2D) slab photonic crystal waveguides (PCWs) when the slab thickness is less than half a wavelength. By using the finite-difference time-domain method, we theoretically demonstrate that two metal plates clad 2D PCWs (MCPCWs) constructed by sandwiching a PCW into two parallel metal plates can well compress light field in the vertical direction of PCW plane. A method for improving the propagation efficiency of MCPCWs is suggested and demonstrated numerically. Our result implies that MCPCWs may provide another method to create planar PC devices on metallic surfaces for highly integrated optical circuits.
Highly dispersive photonic crystal-based coupled-cavity structures
Authors: Talneau A. , Aubin G. , Uddhammar A. , Berrier A. , Mulot M. , Anand S.
Published: May 2006

We measured the wavelength dependence of the group velocity dispersion (GVD) for different photonic-crystal coupled-cavity structures through a phase analysis of the transmitted modulated signal. GVD values as large as 106–107 times the dispersion of a standard single mode fiber are obtained when operating close to the band edge of the miniband, in agreement with the calculated group index. The GVD is found to be smaller for the structure based on more open cavities.
Effective fabrication of three-dimensional nano/microstructures in a single step using multilayered stamp
Authors: Park Sang-Hu , Lim Tae-Woo , Yang Dong-Yol , Jeong Jun-Ho , Kim Ki-Don , Lee Kwang-Sup , Kong Hong-Jin
Published: May 2006

A technique in ultraviolet nanoimprint lithography (UV-NIL) for the creation of three-dimensional (3D) nanopatterns in a single step is proposed. The single-step fabrication of 3D or multilevel structures has a multitude of benefits. Inherent in this is the elimination of a need for alignment for multilevel fabrications as well as being a cost effective and simple process. For 3D UV-NIL, a trial in the fabrication of multilayered stamps has been conducted employing two-photon polymerization and diamondlike carbon (DLC) coating technique. The DLC coating layer enables the polymer patterns to be used effectively as a stamp without the need for an antiadhesion material. Additionally, O2-plasma ashing has the potential for an epoch-making improvement of the precision of polymer patterns with a linewidth of 60nm. Overall, several fine patterns are imprinted using the multilayered stamp onto a UV-curable resist via a single-step process without any identifiable damage.