bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of GaAs interlayer thickness variations on the optical properties of multiple InAs QD structure
Authors: Park C. Y. , Kim J. M. , Park K. W. , Lee Y. T. 
Published: December 2008

AbstractMultiple InAs/GaAs self‐assembled quantum dots (QDs) with vertically stacked structure are grown by molecular beam epitaxy and the effects of GaAs interlayer thickness variation on optical properties are studied. The growth conditions are optimized by in‐situ RHEED, AFM, and PL measurement. The five InAs QD layers are embedded in GaAs and Al0.3Ga0.7As layer. The PL intensity is increased with increasing GaAs interlayer thickness. The thin GaAs interlayer has strain field, the strain‐induced intermixing of indium atoms in the InAs QDs (blue‐shift) can overcompensate for the effect on the increased QD size (red‐shift) (H. Heidemeyer et al. Appl. Phys. Lett. 80, 1544 (2002); T. Nakaoka et al. J. Appl. Phys. Lett. 96, 150 (2004) [1, 2], respectively). For the interlayer thickness larger than about 7 nm, the blue‐shifts are correlated to the dominant high‐energy excited state transitions due to the successive state filling of the ground and higher excited states in the QDs. The energy separation of double PL peaks, originated from two different excited states, was kept at around 50 meV at room temperature. A possible mechanism concerning this phenomenon is also discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The synthesis of CdSe quantum dots with carboxyl group and study on their optical characteristics
Authors: Ye Chen , Park Sangjoon , Kim Jongsung 
Published: December 2008

AbstractQuantum dots are nanocrystal semiconductors which attract lots of research interests due to their peculiar optical properties. CdSe/ZnS quantum dots have been synthesized via pyrolysis of organometallic reagents. The color of the quantum dot changes from yellow‐green to red as their size increases with reaction time. Photoluminescence quantum efficiency of CdSe quantum dots have been enhanced by passivating the surface of CdSe quantum dots with ZnS layers. Quantum dots are nanocrystal semiconductors which attract lots of research interests due to their peculiar optical properties. CdSe/ZnS quantum dots have been synthesized via pyrolysis of organometallic reagents. The color of the quantum dot changes from yellow‐green to red as their size increases with reaction time. Photoluminescence quantum efficiency of CdSe quantum dots have been enhanced by passivating the surface of CdSe quantum dots with ZnS layers. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Decoherence of single photons from an InAs/InP quantum dot emitting at a 1.3 μm wavelength
Authors: Kuroda Takashi , Sakuma Yoshiki , Sakoda Kazuaki , Takemoto Kazuya , Usuki Tatsuya 
Published: December 2008

AbstractThe coherence of light emitted from an isolated InAs/InP quantum dot (QD) is characterized by observing the firstorder correlation functions, g(1)(τ) of the electric field. The function of g(1)(τ) at 8 K shows an exponential decay with a decay time of 130 (±5) ps, corresponding to a Lorentzian spectral shape with 10.2 (±0.4) μeV in full width at half maximum. We observed systematic variation in g(1)(τ) as a function of temperature and excitation power. Our findings suggest that the motion of carriers surrounding QDs had a crucial effect on the decoherence (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mapping, navigation, and learning for off‐road traversal
Authors: Konolige Kurt , Agrawal Motilal , Blas Morten Rufus , Bolles Robert C. , Gerkey Brian , Solà Joan , Sundaresan Aravind 
Published: December 2008

AbstractThe challenge in the DARPA Learning Applied to Ground Robots (LAGR) project is to autonomously navigate a small robot using stereo vision as the main sensor. During this project, we demonstrated a complete autonomous system for off‐road navigation in unstructured environments, using stereo vision as the main sensor. The system is very robust—we can typically give it a goal position several hundred meters away and expect it to get there. In this paper we describe the main components that comprise the system, including stereo processing, obstacle and free space interpretation, long‐range perception, online terrain traversability learning, visual odometry, map registration, planning, and control. At the end of 3 years, the system we developed outperformed all nine other teams in final blind tests over previously unseen terrain. © 2008 Wiley Periodicals, Inc.
Gamma‐SLAM: Visual SLAM in unstructured environments using variance grid maps
Authors: Marks Tim K. , Howard Andrew , Bajracharya Max , Cottrell Garrison W. , Matthies Larry H. 
Published: December 2008

AbstractThis paper describes an online stereo visual simultaneous localization and mapping (SLAM) algorithm developed for the Learning Applied to Ground Robotics (LAGR) program. The Gamma‐SLAM algorithm uses a Rao–Blackwellized particle filter to obtain a joint posterior over poses and maps: the pose distribution is estimated using a particle filter, and each particle has its own map that is obtained through exact filtering conditioned on the particle's pose. Visual odometry is used to provide good proposal distributions for the particle filter, and maps are represented using a Cartesian grid. Unlike previous grid‐based SLAM algorithms, however, the Gamma‐SLAM map maintains a posterior distribution over theelevation variancein each cell. This variance grid map can capture rocks, vegetation, and other objects that are typically found in unstructured environments but are not well modeled by traditional occupancy or elevation grid maps. The algorithm runs in real time on conventional processors and has been evaluated for both qualitative and quantitative accuracy in three outdoor environments over trajectories totaling 1,600 m in length. © 2008 Wiley Periodicals, Inc.
Information systems research with system dynamics
Authors: Georgantzas Nicholas C. , Katsamakas Evangelos G. 
Published: December 2008

AbstractCatering to the growing community of scholars and practitioners who research information systems (IS) with system dynamics (SD), this article sketches IS research with SD as a genuinely transdisciplinary area that studies the design, implementation, management and effects of IS on people, organizations and markets. A preamble to a fascinating collection of five applied‐research contributions to this System Dynamics Review (SDR) special issue, the article charts IS research and places these contributions in their proper context of IS research with SD. The article outlines criteria and themes for future high‐quality IS research with SD, emphasizing the value of the SD modeling process for IS research. By integrating IS research with SD, this special issue might serve well as a prototype for future SDR special issues, which will further integrate SD with research and practice in other social sciences, and thereby help identify new, exciting opportunities for future research. Copyright © 2008 John Wiley & Sons, Ltd.
On the performance of using Covert Timing Channels for node authentication
Authors: Newman Reed , Beyah Raheem A. 
Published: December 2008

AbstractAuthentication over a network is an important and difficult problem. Accurately determining the authenticity of a node or user is critical in maintaining the security of a network. Our proposed technique covertly embeds a watermark, or identifying tag, within a data stream. By implementing this model on a LAN, WLAN, and VPN connection we show that this method is easily adaptable to a variety of networking technologies, and easily scalable. While our technique increases the time required for data to be transferred, we show that the throughput of the link during the brief authentication window is decreased by no more than 8 percent in a switched LAN, 11 percent in a WLAN, and 9 percent in a VPN. During our empirical analysis we were able to detect the watermark with 100 percent accuracy in a LAN, WLAN, and VPN environment. We also investigate the detectability of the covert channel, and show that this method produces a relatively stealthy covert channel. Copyright © 2008 John Wiley & Sons, Ltd.
Students' technology use and the impacts on well‐being
Authors: Cotten Shelia R. 
Published: December 2008

AbstractThis chapter reviews technology use patterns and the social impacts of technology on well‐being among college students. It provides empirical evidence delineating the processes through which Internet use affects well‐being among college students, and provides suggestions for ways to advance future studies in this area and for higher education faculty and staff as they work with technologically savvy students.
A scoring system to differentiate malignant from benign masses in specific ultrasound‐based subgroups of adnexal tumors
Authors: Ameye L. , Valentin L. , Testa A. C. , Van Holsbeke C. , Domali E. , Van Huffel S. , Vergote I. , Bourne T. , Timmerman D. 
Published: December 2008

AbstractObjectiveTo investigate if the prediction of malignant adnexal masses can be improved by considering different ultrasound‐based subgroups of tumors and constructing a scoring system for each subgroup instead of using a risk estimation model applicable to all tumors.MethodsWe used a multicenter database of 1573 patients with at least one persistent adnexal mass. The masses were categorized into four subgroups based on their ultrasound appearance: (1) unilocular cyst; (2) multilocular cyst; (3) presence of a solid component but no papillation; and (4) presence of papillation. For each of the four subgroups a scoring system to predict malignancy was developed in a development set consisting of 754 patients in total (respective numbers of patients: (1) 228; (2) 143; (3) 183; and (4) 200). The subgroup scoring system was then tested in 312 patients and prospectively validated in 507 patients. The sensitivity and specificity, with regard to the prediction of malignancy, of the scoring system were compared with that of the subjective evaluation of ultrasound images by an experienced examiner (pattern recognition) and with that of a published logistic regression (LR) model for the calculation of risk of malignancy in adnexal masses. The gold standard was the pathological classification of the mass as benign or malignant (borderline, primary invasive, or metastatic).ResultsIn the prospective validation set, the sensitivity of pattern recognition, the LR model and the subgroup scoring system was 90% (129/143), 95% (136/143) and 88% (126/143), respectively, and the specificity was 93% (338/364), 74% (270/364) and 90% (329/364), respectively.ConclusionsIn the hands of experienced ultrasound examiners, the subgroup scoring system for diagnosing malignancy has a performance that is similar to that of pattern recognition, the latter method being the best diagnostic method currently available. The scoring system is less sensitive but more specific than the LR model. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
H2O2 increases de novo synthesis of (6R)‐L‐erythro‐5,6,7,8‐tetrahydrobiopterin via GTP cyclohydrolase I and its feedback regulatory protein in vitiligo
Authors: Chavan B. , Beazley W. , Wood J. M. , Rokos H. , Ichinose H. , Schallreuter K. U. 
Published: December 2008

SummaryPatients with vitiligo accumulate up to 10−3 mol/L concentrations of H2O2 in their epidermis, which in turn affects many metabolic pathways in this compartment, including the synthesis and recycling of the cofactor (6R)‐l‐erythro‐5,6,7,8‐tetrahydrobiopterin (6BH4). De novo synthesis of 6BH4 is dependent on the rate‐limiting enzyme GTP cyclohydrolase I (GTPCHI) together with its feedback regulatory protein (GFRP). This step is controlled by 6BH4 and the essential amino acid l‐phenylalanine. In the study presented here we wanted to investigate whether H2O2 affects the GTPCHI/GFRP cascade in these patients. Our results demonstrated concentration‐dependent regulation of rhGTPCHI where 100 μmol/L H2O2 was the optimum concentration for the activation of the enzyme and >300 μmol/L resulted in a decrease in activity. Oxidation of GFRP and GTPCHI does not affect feedback regulation via l‐phenylalanine and 6BH4. In vitiligo a constant upregulation of 6BH4de novo synthesis results from epidermal build up of l‐phenylalanine that is not controlled by H2O2. Taking the results together, 6BH4de novo synthesis is controlled by H2O2 in a concentration‐dependent manner, but H2O2‐mediated oxidation does not affect the functionality of the GTPCHI/GFRP complex.
Quantitative Monitoring of the Amidation Reaction Between Coconut Oil and Diethanolamine by Attenuated Total Reflectance Fourier Transform Infrared Spectrometry
Authors: Khanmohammadi Mohammadreza , Kojidi Mohammadjavad Hosseinnia , Garmarudi Amir Bagheri , Ashuri Ahmad , Soleymani Majid 
Published: December 2008

AbstractAn analytical procedure was developed to monitor the batch reaction of coconut oil and diethanolamine which also would determine the cocodiethanolamide (CDEA) content of the final product. The method was based on attenuated total reflectance Fourier transform infrared spectrometry utilizing partial least squares regression. The calibration was modeled in the 1,781–1,714 and 1,658–1,639 cm−1 spectral regions for coconut oil and CDEA respectively. The models were then applied to predict the amidation process yield and to monitor the in situ kinetics of reactions between coconut oil and DEA. The root mean square error of prediction was 0.590 and 0.336 for coconut oil and CDEA respectively. The proposed method can also be successfully applied to the determination of purity in commercial grade CDEA samples and would give reliable results in comparison with the potentiometric titration reference method.
The Iberian–Roman Humid Period (2600–1600 cal yr BP) in the Zoñar Lake varve record (Andalucía, southern Spain)
Authors: Martín-Puertas Celia , Valero-Garcés Blas L. , Brauer Achim , Mata M. Pilar , Delgado-Huertas Antonio , Dulski Peter 
Published: December 2008

AbstractThe Iberian–Roman Humid Period (IRHP, 2600–1600 cal yr BP), is the most humid phase of the last 4000 yr in southern Spain as recorded in the sedimentary sequence of Zoñar Lake (37°29′00″N, 4°41′22″ W, 300 m a.s.l.). A varve chronology supported by several AMS14C dates allows study of the lake evolution at annual scale in response to human impact and climate changes. There are four climate phases within this period: i) gradual transition (2600–2500 yr ago, 650–550 BC) from a previous arid period; ii) the most humid interval during the Iberian–Early Roman Epoch (2500–2140 yr ago, 550–190 BC); iii) an arid interval during the Roman Empire Epoch (2140–1800 yr ago, 190 BC AD 150); and iv) a humid period synchronous with the decline of the Roman Empire (1800–1600 yr ago, AD 150–350). Varve thickness and geochemical proxies show a multi-decadal cyclicity similar to modern North Atlantic Oscillation (NAO) (60, 20 years) and solar variability cycles (11 yr). The timing and the structure of this humid period is similar to that described in Eastern Mediterranean and northern European sites and supports the same large-scale climate control for northern latitudes and the Mediterranean region.
Positive p-summing operators, vector measures and tensor products
Authors: Blasco Oscar 
Published: December 2008

In this paper we shall introduce a certain class of operators from a Banach lattice X into a Banach space B (see Definition 1) which is closely related to p-absolutely summing operators defined by Pietsch [8].These operators, called positive p-summing, have already been considered in [9] in the case p = 1 (there they are called cone absolutely summing, c.a.s.) and in [1] by the author who found this space to be the space of boundary values of harmonic B-valued functions in .Here we shall use these spaces and the space of majorizing operators to characterize the space of bounded p-variation measures and to endow the tensor product with a norm in order to get as its completion in this norm.
A series for ζ(s)
Authors: Balakrishnan U. 
Published: December 2008

We obtain a series representation for ζ(s) valid in Res> – k(<0). This representation is obtained by a sequence of regrouping of the series 1–2−s + 3−s–4−s + …( = (1—21−s)ζ(s), Re s > 0). We can obtain asymptotic relations likeas an application of our series representation for ζ(s).
Engel-like elements in infinite soluble groups
Authors: Brandl Rolf R. A. , Brookes Christopher J. B. 
Published: December 2008

In [1] the first author considered the following Engel-like condition for a pair of elements x, y of a group G.There exist r = r(x, y)≧0 and d = d(x, y)≧1 such that[x,ry] = [x,r+dy]. (*)
Convolution theorems of Titchmarsh type on discrete Rn
Authors: Domar Yngve 
Published: December 2008

SummaryThis paper contains results related to Titchmarsh's convolution theorem and valid for , the additive group of Rn with the discrete topology. The method of proof consists in transferring the problem to Rn with the usual topology by a procedure which has been used earlier, for instance in Helson [3].In Section 1, the classical support theorems are generalized to . In [1], Titchmarsh's convolution theorem [6] on R was generalized to convolutions of functions belonging to certain weighted Lp-spaces on R. Section 2 contains a corresponding generalization to weighted l2(Rd).It should be observed that convolutions of elements f and g in l1() can be interpreted as convolutions of bounded discrete measures on Rn. Hence, in that case the support theorem (Theorem 4.33 of Hörmander [5]) is directly applicable to give the results of our Theorems 1 and 3. So the novelty in our theorems lies in the fact that they apply for instance to the case when it is only assumed f, g ∈l2(), together with support conditions. It is not known whether it suffices to assume f∈l1(), g∈lp(), when p > 2.
Homotopy associativity of sphere extensions
Authors: Iwase N. 
Published: December 2008

Throughout this paper, we work in the category of (p-localized) spaces having the homotopy type of connected CW-complexes of finite type with base point. We consider a principal bundlewhereGn=SU(n),U(n) orSp(n) andd= 1, 1 or 2 respectively. In this case, the bundle is obtained as an induced bundle by a mappingfof base spaceS2dn−1from the classical group extension as follows:
On radial variation of holomorphic functions with lp Taylor coefficients
Authors: Hallenbeck D. J. , Samotij K. 
Published: December 2008

Suppose is holomorphic in Δ = {z:|z|<l} and (an)∈lp where 1≦p≦2. We prove that for k=1,2,…, and almost every θ. This result is sharp in the following sense: Let p∈[1,2] and ε(r) be a positive function defined on [0,1] such that limr→1-ε(r)=0. Then there exists a function holomorphic in Δ with (an)∈lp such thatfor each k>1/p.
Regular bisimple rings
Authors: Hannah John 
Published: December 2008

We characterize regular bisimple rings in terms of some perspectivity conditions on their lattices of principal right ideals. We also show that, if S is the multiplicative subsemigroup generated by all the idempotents of a regular bisimple ring R, then(i) if R does not have an identity, then S = R and has depth 2;(ii) if R does have an identity but is not a division ring, then S = {a∈R:a is neither left nor right invertible} ∪ {1} and has depth 3.
The number of permutation polynomials of the form f(x) cx over a finite field
Authors: Wan Daqing , Mullen Gary L. , Shiue Peter Jau-Shyong 
Published: December 2008

Let Fq be the finite field of q elements. Let f(x) be a polynomial of degree d over Fq and let r be the least non-negative residue of q-1 modulo d. Under a mild assumption, we show that there are at most r values of c∈Fq, such that f(x) + cx is a permutation polynomial over Fq. This indicates that the number of permutation polynomials of the form f(x) +cx depends on the residue class of q–1 modulo d.As an application we apply our results to the construction of various maximal sets of mutually orthogonal latin squares. In particular for odd q = pn if τ(n) denotes the number of positive divisors of n, we show how to construct τ(n) nonisomorphic complete sets of orthogonal squares of order q, and hence τ(n) nonisomorphic projective planes of order q. We also provide a construction for translation planes of order q without the use of a right quasifield.
Inverse multiparameter eigenvalue problems for matrices III
Authors: Browne Patrick J. , Sleeman B. D. 
Published: December 2008

This note will complement and, in a certain sense, complete our earlier studies [3, 4] of the theory of inverse multiparameter eigenvalue problems for matrices. In those papers, we considered the so called “additive inverse problem” which, briefly stated for the 2-parameter case, asks for conditions on given n × n matrices A, B, C and on given points (si, ti) ∈ ℝ2, 1 ≦ i ≦ n, under which a diagonal matrix D can be found so that the 2-parameter eigenvalue problemcan be solved when (λ,μ)=(si, ti), 1 = i = n. Put another way, we look for conditions ensuring that the points (si, ti), 1 ≦ i ≦ n, belong to the eigenvalues of (1.1).
Multiparameter root vectors
Authors: Binding Paul 
Published: December 2008

The concept of “root vectors” is investigated for a class of multiparameter eigenvalue problemswhere operate in Hilbert spaces Hm and . Previous work on this “uniformly elliptic” class has demonstrated completeness of the decomposable tensors x1 ⊗…⊗ xk in a subspace G of finite codimension in H=H1 ⊗…⊗ Hk, but questions remain about extending this to a basis of H. In this work, bases of elements ym, in general nondecomposable but satisfying recursive equations of the type are constructed for the “root subspaces” corresponding to λ∈ℝk.
Distributive elements in the near-rings of polynomials
Authors: Gutierrez Jaime , De Velasco Y Bellas Carlos Ruiz 
Published: December 2008

As usual in the theory of polynomial near-rings, we deal with right near-rings. If N = (N, +,·) is a near-ring, the set of distributive elements of N will be denoted by Nd;It is easy to check that, if N is an abelian near-ring (i.e., r + s = s + r, for all r, s∈N), then Nd is a subring of N.
Embeddings into finite idempotent-generated semigroups: some arithmetical results
Authors: Giraldes Emilia , Howie John M. 
Published: December 2008

A semiband is defined as a semigroup generated by idempotents. It is known that every finite semigroup is embeddable in a finite semiband. For a class C of semigroups and an integer n≧2, the number σC (n) is defined as the smallest k with the property that every semigroup of order n in the class C is embeddable in a semiband of order not exceeding k. It is shown that for the class Gp of groups σGp(n) = nq(ρGp(n)), whereandEstimates are known (and are quoted) for the function q. Estimates are considered for the function pC for various CIt is shown also that if C0S, CS denote respectively the classes of completely 0-simple and completely simple semigroups, then
Hilbert spaces of tempered distributions, Hermite expansions and sequence spaces
Authors: Picard Rainer H. 
Published: December 2008

Although it is well-known that tempered distributions on ℝn can be expanded into series of Herrnite functions, it does not seem to be known, however, that expansions of this type are accessible through the elementary concept of orthonorma! expansions in Hilbert space. This approach is developed here complementing previous work on a Hilbert space approach to distributions. The basis of the development is the observation that the Hermite functions are a complete orthogonal set in each space of a certain scale of Sobolev type Hilbert spaces associated with the family of differential operators defined byHere Ф denotes a smooth function with compact support. The setting is first developed in the one-dimensional case. By use of the usual multi-index notation this can be extended to the higher-dimensional case. As applications various imbedding results are derived. The paper concludes with a characterization of tempered distributions by convergent Hermite expansions.