bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy transfer in hybrid CdSe quantum dots vs. labelled molecular chaperone systems by imaging microscopy
Authors: Tani Toshiro , Horiuchi Hiromi , Oda Masaru , Usukura Eiji , Sakai Hiroshi , Ohtaki Akashi , Yohda Masafumi
Published: December 2008

Resonant energy transfer in hybrid CdSe quantum dot (QD) conjugated with Cy5‐labelled molecular chaperone systems is observed with single molecule imaging technique. Photonic QDs are the core‐shell type nanocrystals covered with organic surfactants on the outermost surfaces, i.e. CdSe/ZnS/TOPO's, and prefoldin (PFD) is used as prototype molecular chaperons. PFD is a jellyfish‐shaped hexameric co‐chaperone of group II chaperonins, which recognize hydrophobic portion of denatured proteins and encapsulate them within its central cavity. So the CdSe/ZnS/TOPO QDs can also be captured be cause of its surface similarity to the denatured proteins. We have found one possible reaction pathway to get such artificial complex in aqueous solutions with keeping bioactivities of the proteins. Performance of the complex is evaluated by TIRF imaging microscopy. As the proteins are transparent in visible wavelength region, labeling dyes, Cy5, which also work as acceptors, are connected to detect their behaviors microscopically. Förster type energy transfer is observed from the QD donors to Cy5‐labeled PFD acceptors in single molecule level, which can be a distinct evidence for the complex formation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
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

Multiple 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

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. 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

The 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

The 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

This 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

Catering 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

Authentication 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.
An introduction to technologies commonly used by college students
Authors: Junco Reynol , Cole‐Avent Gail A.
Published: December 2008

Newer communication technologies are a regular part of students' lives. It is important to understand how and why students are using these technologies in order to best serve them and improve educational outcomes.
Technology use in campus crisis
Authors: Mastrodicasa Jeanna
Published: December 2008

College students are connecting with peers and college administrators in different ways in times of crisis. Lessons learned from the impact of Hurricane Katrina and the mass shooting at Virginia Tech have shifted the methods of response in the event of campus crisis to newer technologies.
Students' technology use and the impacts on well‐being
Authors: Cotten Shelia R.
Published: December 2008

This 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.
Privacy and social networking sites
Authors: Timm Dianne M. , Duven Carolyn J.
Published: December 2008

College students are increasingly sharing their lives online through social networking sites with little concern for who may be viewing their information. Understanding student use of social networking sites along with privacy rights online will help professionals in the development of appropriate online activity and policies.
Technology for institutional enrollment, communication, and student success
Authors: Salas Grace , Alexander Julie S.
Published: December 2008

While students are updating their most recent social networking sites, faculty, staff, and administrators are using the latest technology to do everything from managing preenrollment student contacts to increasing collaboration among academic and student affairs colleagues.
Knowledge is no longer enough: Enhancing professional education with team‐based learning
Authors: Sibley Jim , Parmelee Dean X.
Published: December 2008

Professional schools must cultivate specific competencies within their students in order to prepare them for their professions, and these competencies are changing. Team‐based learning is ideally suited to meet the demands placed on professional schools as they confront new challenges.
Team‐based learning in asynchronous online settings
Authors: Palsolé Sunay , Awalt Carolyn
Published: December 2008

In implementing team‐based learning in a purely online, asynchronous course, the authors advise planning early and planning well, a process for which they provide specific advice.
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

Objective

To 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.

Methods

We 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).

Results

In 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.

Conclusions

In 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

Patients 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

An 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.
Surgical management of vertebral malformation in a Manx cat
Authors: Havlicek Martin , Mathis Karl R. , Beck Jason A. , Allan Graeme S.
Published: December 2008

A 15-week-old Manx kitten was presented for evaluation of progressive hind limb paresis and ataxia. Spinal radiographs and computed tomography revealed a malformation of T3 causing thoracic spinal cord compression. Decompressive surgery consisting of dorsal laminectomy, without vertebral stabilisation, resulted in improvement of clinical signs.
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

The 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.
Embeddings of infinite permutation groups in sharp, highly transitive, and homogeneous groups
Authors: Adeleke S. A.
Published: December 2008

This paper answers two questions posed by P. M. Neumann and K. Hickin on embeddings of infinite permutation groups. We first give some definitions that would make their questions understood.
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.
More on automorphism groups of laminated near-rings
Authors: Blevins D. K. , Magill K. D. , Misra P. R. , Parnami J. C. , Tewari U. B.
Published: December 2008

We will assume throughout this paper that polynomials are nonconstant. Let P be any complex polynomial and let p denote the near-ring of all continuous selfmaps of the complex plane where addition of functions is pointwise and multiplication is defined by fg = f ο P ο g for all f,g∈p. The near-ring p is referred to as a laminated near-ring and P is referred to as the laminating element or laminator. In [1] the problem was posed of determining Aut p the automorphism group of p. It was shown that exactly three infinite groups occur as automorphism groups of the laminated near-rings p and for each of the three groups those polynomials P were characterized such that Aut p is isomorphic to that particular group. The infinite groups turn out to be GL(2), the full linear group of all 2×2 nonsingular real matrices and two of its subgroups.
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 like

as an application of our series representation for ζ(s).
Hausdorff dimension of Banach spaces
Authors: De Reyna J. Arias
Published: December 2008

We show that if X is a Banach space of infinite dimension and μh is a Hausdorff measure, where h is continuous, then there exists a measurable set K ⊂ X such that 0<μh(K)< + ∞. We also characterize the normed spaces in which the unit ball can be covered by a sequence of balls whose radii rn < 1 converge to zero as n → ∞.
Certain characterizations of varieties of bands
Authors: Gerhard J. A. , Petrich Mario
Published: December 2008

The lattice of varieties of bands was constructed in [1] by providing a simple system of invariants yielding a solution of the world problem for varieties of bands including a new system of inequivalent identities for these varieties. References [3] and [5] contain characterizations of varieties of bands determined by identities with up to three variables in terms of Green's relations and the functions figuring in a construction of a general band. In this construction, the band is expressed as a semilattice of rectangular bands and the multiplication is written in terms of functions among these rectangular band components and transformation semigroups on the corresponding left zero and right zero direct factors.
On crossed products and Takai duality
Authors: Raeburn Iain
Published: December 2008

The Takai duality theorem has proved to be a fundamental tool in the theory of crossed products of C*-algebras. It was inspired by Takesaki's duality theorem for crossed products of von Neumann algebras [7], so it is not surprising that the original proof [6] depended heavily on spatial techniques. Here we shall prove Takai's theorem by exploiting the universal properties of crossed products.
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]. (*)
On the “zero-two” law for positive contractions
Authors: Zaharopol Radu
Published: December 2008

Let (X, Σ,μ) be a measure space (where μ is a positive σ-additive measure) and let Lp(X,Σ,μ), 1≦p≦ + ∞ be the usual real Banach lattices.
Sufficient conditions for a well-behaved Kurosh-Amitsur radical theory
Authors: Veldsman Stefan
Published: December 2008

Kurosh-Amitsur radical theories have been developed for various algebraic structures. Whenever the notion of a normal substructure is not transitive, this causes quite some problems in obtaining satisfactory general results. Some of the more important questions concerning the general theory of radicals are whether semisimple classes are hereditary, do radical classes satisfy the ADS-property, can semisimple classes be characterized by closure conditions (e.g., is semisimple=coradical), is Sands' Theorem valid and lastly, does the lower radical construction terminate. For associative and alternative rings, all these questions have positive answers. The method of proof is the same in both cases. In [15], Puczylowski used the results of Terlikowska-Oslowska [18, 19] and hinted at a condition which is crucial in obtaining the positive answers to the above questions.
Convolution theorems of Titchmarsh type on discrete Rn
Authors: Domar Yngve
Published: December 2008

This 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 bundle

whereGn=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:
Modularity of the lattice of congruences of a regular ω-semigroup
Authors: Bonzini C. , Cherubini A.
Published: December 2008

In this paper a characterization of the regular ω-semigroups whose congruence lattice is modular is given. The characterization obtained for such semigroups generalizes the one given by Munn for bisimple ω-semigroups and completes a result of Baird dealing with the modularity of the sublattice of the congruence lattice of a simple regular ω-semigroup consisting of congruences which are either idempotent separating or group congruences.
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 that

for each k>1/p.
Some characterizations of π-regular rings with no infinite trivial subring
Authors: Hirano Yasuyuki
Published: December 2008

It is shown that a ringRis a π-regular ring with no infinite trivial subring if and only ifRis a subdirect sum of a strongly regular ring and a finite ring. Some other characterizations of such a ring are given. Similar result is proved for a periodic ring. As a corollary, it is shown that every δ-ring is a subdirect sum of a Unite ring and a commutative ring. This was conjectured by Putcha and Yaqub.
On the extensions of some classical distributions
Authors: Ranga A. Sri , McCabe J. H.
Published: December 2008

Some properties of polynomials associated with strong distribution functions are given, including conditions for the polynomials to satisfy a three term recurrence relation. Strong distributions that are extensions to the four classical distributions are given as examples.
Normal semigroups of one-to-one transformations
Authors: Levi Inessa
Published: December 2008

Let X be an infinite set and S be a transformation semigroup on X invariant under conjugations by permutations of X. Such S is termed x-normal. In the paper, we describe elements of a x-normal semigroup S of one-to-one transformations.
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.
A lower bound for a remainder term associated with the sum of digits function
Authors: Foster D. M. E.
Published: December 2008

For a fixed integer q≧2, every positive integer k = Σr≧0ar(q, k)qr where each ar(q, k)∈{0,1,2,…, q−1}. The sum of digits function α(q, k) Σr≧0ar(q, k) behaves rather erratically but on averaging has a uniform behaviour. In particular if , where n>1, then it is well known that A(q, n)∼½((q − 1)/log q)n logn as n → ∞. For odd values of q, a lower bound is now obtained for the difference 2S(q, n) = A(q, n)−½(q − 1))[log n/log q, where [log n/log q] denotes the greatest integer ≦log n /log q. This complements an upper bound already found.
Modules whose closed submodules are finitely generated
Authors: Dung Nguyen V.
Published: December 2008

A module M is called a CC-module if every closed submodule of M is cyclic. It is shown that a cyclic module M is a direct sum of indecomposable submodules if all quotients of cyclic submodules of M are CC-modules. This theorem generalizes a recent result of B. L. Osofsky and P. F. Smith on cyclic completely CS-modules. Some further applications are given for cyclic modules which are decomposed into projectives and injectives.
Surfaces with isometric geodesics
Authors: Charitos C. , Pamfilos P.
Published: December 2008

The aim of the paper is to prove the Theorem: Let M be a surface in the euclidean space E3 which is diffeomorphic to the sphere and suppose that all geodesies of M are congruent. Then M is a euclidean sphere.
On inequalities of Hilbert and Widder
Authors: Mitrinović Dragoslav S. , Pečarić Josip E.
Published: December 2008

A short proof of Chow's generalization of Widder's inequality and generalizations of some related Hardy's results are given.
Relative relation modules of finite groups
Authors: Yamin Mohammad
Published: December 2008

Let E be a free product of a finite number of cyclic groups, and S a normal subgroup of E such that E/S ≅ G is finite. For a prime p, Ŝ = S / S′Sp may be regarded as an -module. Whenever E is a free group, Ŝ is called a relation module (modulo p); in general we call Ŝ a relative relation module (modulo p). Gaschütz, Gruenberg and others have studied relation modules; the aim of this paper is to study relative relation modules.
Eigenvalues of smooth positive definite kernels
Authors: Reade J. B.
Published: December 2008

For positive definite C1 kernels on a finite real interval the eigenvalues λn are known to be o(1/n2). In this paper this result is shown to be best possible in the best possible sense, namely that, given any decreasing sequence λn, which is o(1/n2), there exist positive definite C1 kernels whose eigenvalues are λn.
Some remarks on Levi complements and roots in Lie algebras with cone potential
Authors: Spindler Karlheinz
Published: December 2008

We study Lie algebras with cone potential which play a prominent role in the Lie theory of semigroups. For these algebras, we obtain a uniqueness theorem for Levi complements and information on the fine structure of the root system.
Automorphism groups of covering posets and of dense posets
Authors: Behrendt Gerhard
Published: December 2008

Given a poset (X, ≦), the covering poset (C(X), ≦) consists of the set C(X) of covering pairs, that is, pairs (a, b)∈X2 with a<b such that there is no c∈X with a<c<b, partially ordered by (a, b)≦(a′, b′) if and only if (a, b) = (a′, b′) or b≦a′. There is a natural homomorphism v from the automorphism group of (X, ≦) into the automorphism group of (C(X), ≦). It is shown that given groups G, H and a homomorphism α from G into H there exists a poset (X, ≦) and isomorphisms φψ from G onto Aut(X, ≦), respectively from H onto Aut(C(X), ≦) such that φv = αψ. It is also shown that every group is isomorphic to the automorphism group of a poset all of whose maximal chains are isomorphic to the nationals.
On Bernstein algebras which are train algebras
Authors: Walcher Sebastian
Published: December 2008

The class of non-associative algebras over a field of characteristic zero named in the title is studied using a result of Ouattara [9]. As an application, the differential equation for overlapping generations in the time-continuous model is solved.
Periodic Fibonacci algebras
Authors: Johnson D. L. , Kim A. C.
Published: December 2008

Fibonacci algebras are groups equipped with an extra unary operation φ that satisfies a Fibonacci-type law. We described in an earlier paper the free objects in the resulting varieties, and here we do the same in the case when φ is assumed to be periodic. They turn out to be central extensions of Burnside groups with finite kernels whose orders can be expressed in terms of the resultants of certain polynomials.
Unique factorisation rings
Authors: Chatters A. W. , Gilchrist M. P. , Wilson D.
Published: December 2008

Let R be a ring. An element p of R is a prime element if pR = Rp is a prime ideal of R. A prime ring R is said to be a Unique Factorisation Ring if every non-zero prime ideal contains a prime element. This paper develops the basic theory of U.F.R.s. We show that every polynomial extension in central indeterminates of a U.F.R. is a U.F.R. We consider in more detail the case when a U.F.R. is either Noetherian or satisfies a polynomial identity. In particular we show that such a ring R is a maximal order, that every height-1 prime ideal of R has a classical localisation in which every two-sided ideal is principal, and that R is the intersection of a left and right Noetherian ring and a simple ring.
Normal embeddings of p-groups into p-groups
Authors: Heineken Hermann
Published: December 2008

A well known lemma of Burnside is generalised, to give necessary and sufficient conditions for a finite p-group K to be normally embedded in a nilpotent group V, with K⊆ω(V). (Here, ω denotes a single word and ω(V) is the corresponding verbal subgroup.) Our main result is related to earlier work of Blackburn, Gaschütz and Hobby.
Weak and cyclic amenability for non-commutative Banach algebras
Authors: Grønbæk Niels
Published: December 2008

This paper is concerned with two notions of cohomological triviality for Banach algebras, weak amenability and cyclic amenability. The first is defined within Hochschild cohomology and the latter within cyclic cohomology. Our main result is that where ℱ is a Banach algebraic free product of two Banach algebras and ℬ. It follows that cyclic amenability is preserved under the formation of free products.
Sum of two inner functions and exposed points in H1
Authors: Nakazi Takahiko
Published: December 2008

If h is an outer function in H1 then it is shown that h = (q1 + q2)g where both q1 and q2 are inner functions with Im almost everywhere, and g is a strong outer function (equivalently, g/∥g∥1 is an exposed point of the unit ball of H1). If q1 + q2 is nonconstant then such an h is not strongly outer. Moreover a sum of two inner functions is studied.
Casson's invariant and surgery on knots
Authors: Frohman C. D. , Long D. D.
Published: December 2008

We show that given a knot in a homology sphere there is a sequence of invariants with the property that if the nth invariant does not vanish, then this implies the existence of a family of irreducible representations of the fundamental group of the complement of the knot into SU(n).
The Frattini subalgebra of a Bernstein algebra
Authors: Laliena Jesús
Published: December 2008

Let A be a finite-dimensional Bernstein algebra over a field K with characteristic not 2. Maximal subalgebras of A are studied, and they are determined if A is a genetic algebra. It is also proved that the intersection of all maximal subalgebras of A (the Frattini subalgebra of A) is always an ideal. Finally the structure of Bernstein algebras with Frattini subalgebra equal to zero is described.
Existence of positive radial solutions for a class of nonlinear singular elliptic problems in annular domains
Authors: Guo Zongming
Published: December 2008

We establish the existence of positive radially symmetric solutions of Δu+f(r,u,u′) = 0 in the domainR1<r<R0with a variety of Dirichlet and Neumann boundary conditions. The functionfis allowed to be singular when eitheru= 0 oru′ = 0. Our analysis is based on Leray-Schauder degree theory.
Averaging the sum of digits function to an even base
Authors: Foster D. M. E.
Published: December 2008

For a fixed integer q≧2, every positive integer where each ar(q, k) ∈ {0, 1, 2, …, q–1}. The sum of digits function α(q, k) = behaves rather erratically but on averaging has a uniform behaviour. In particular if A(q, n) = , where n > 1, then it is well known that A(q, n)∼½ ((q – 1)/log q) n log n as n→∞. For even values of q, a lower bound is now given for the difference ½S(q, n) = A(q, n)–½(q–1)[logn/logq] n, where [log n/log q] denotes the greatest integer ≦ log n/log q, complementing an earlier result for odd values of q.
Asymptotic behaviour of ideals relative to injective modules over commutative Noetherian rings II
Authors: Toroghy H. Ansari , Sharp R. Y.
Published: December 2008

Let E be an injective module over a commutative Noetherian ring A (with non-zero identity), and let a be an ideal of A. The submodule (0:Eα) of E has a secondary representation, and so we can form the finite set AttA(0:Eα) of its attached prime ideals. In [1, 3.1], we showed that the sequence of sets is ultimately constant; in [2], we introduced the integral closure a*(E) of α relative to E, and showed that is increasing and ultimately constant. In this paper, we prove that, if a contains an element r such that rE = E, then is ultimately constant, and we obtain information about its ultimate constant value.
The determination of the surface impedance of an obstacle
Authors: Kȩdzierawski Andrzej W.
Published: December 2008

The inverse scattering problem we consider is to determine the surface impedance of a three-dimensional obstacle of known shape from a knowledge of the far-field patterns of the scattered fields corresponding to many incident time-harmonic plane acoustic waves. We solve this problem by using both the methods of Kirsch-Kress and Colton-Monk.
On linear independence for integer translates of a finite number of functions
Authors: Jia Rong-Qing , Micchelli Charles A.
Published: December 2008

We investigate linear independence of integer translates of a finite number of compactly supported functions in two cases. In the first case there are no restrictions on the coefficients that may occur in dependence relations. In the second case the coefficient sequences are restricted to be in somelpspace (1 ≦p≦ ∞) and we are interested in bounding theirlp-norms in terms of theLp-norm of the linear combination of integer translates of the basis functions which uses these coefficients. In both cases we give necessary and sufficient conditions for linear independence of integer translates of the basis functions. Our characterization is based on a study of certain systems of linear partial difference and differential equations, which are of independent interest.
Extreme n-positive linear maps
Authors: Tsui Sze-Kai
Published: December 2008

In this article we prove that if a completely positive linear map Φ of a unital C*-algebra A into another B with only finite dimensional irreducible representations is pure, then we have NΦ = Φker + kerΦ, where NΦ={x∈A|Φ(x) = 0}, Φker = {x∈A|Φ(x*x) = 0}, and kerΦ={x∈A|Φ(xx*) = 0}. We also prove that for every unital strongly positive and n-positive linear map Φ of a C*-algebra A onto another B with n≧2, if NΦ = Φker + kerΦ, then Φ is extreme in Pn(A, B, IB). By this null-kernel condition, many new extreme n-positive linear maps are identified. A general procedure for constructing extreme n-positive linear maps is suggested and discussed.
Harmonic morphisms between spaces of constant curvature
Authors: Gudmundsson Sigmundur
Published: December 2008

Let M and N be simply connected space forms, and U an open and connected subset of M. Further let π: U → N be a horizontally homothetic harmonic morphism. In this paper we show that if π has totally geodesic fibres and integrable horizontal distribution, then the horizontal foliation of U is totally umbilic and isoparametric. This leads to a classification of such maps. We also show that horizontally homothetic harmonic morphisms of codimension one are either Riemannian submersions modulo a constant, or up to isometrics of M and N one of six well known examples.
Multipliers of invariant subspaces in the bidisc
Authors: Nakazi Takahiko
Published: December 2008

For any nonzero invariant subspace M in H2(T2), set . Then Mx is also an invariant subspace of H2(T2) that contains M. If M is of finite codimension in H2(T2) then Mx = H2(T2) and if M = qH2(T2) for some inner function q then Mx = M. In this paper invariant subspaces with Mx = M are studied. If M = q1H2(T2) ∩ q2H2(T2) and q1, q2 are inner functions then Mx = M. However in general this invariant subspace may not be of the form: qH2(T2) for some inner function q. Put (M) = {ø ∈ L ∞: ø M ⊆ H2(T2)}; then (M) is described and (M) = (Mx) is shown. This is the set of all multipliers of M in the title. A necessary and sufficient condition for (M) = H∞(T2) is given. It is noted that the kernel of a Hankel operator is an invariant subspace M with Mx = M. The argument applies to the polydisc case.
(p, r)-convex functions on vector lattices
Authors: Szulga Jerzy
Published: December 2008

We study certain convexity-type properties of homogeneous functions on topological vector lattices, focusing on a concept of 0+-convexity, and using some probabilistic inequalities.
Some results on symmetrically-presented groups
Authors: Johnson D. L. , Odoni R. W. K.
Published: December 2008

Necessary and sufficient conditions are found on an ideal a⊲ℤ[x] for the additive group [a]+ of ℤ[x]/a to be finite and cyclic. As a consequence, the abelianizations of certain cyclically-presented groups are computed explicitly.
Stability of Gelfand–Kirillov dimension for rings with the strong second layer condition
Authors: Lenagan T. H.
Published: December 2008

We study the influence of the link structure of the prime spectrum of a Noetherian ring on the representation theory of the ring in the case that the ring satisfies the strong second layer condition and has exact integer Gelfand–Kirillov dimension. In particular, we show that Jategaonkar's density condition is satisfied and that the growth of an injective module is controlled by the growth of its first layer.
Linear metric spaces and analytic sets
Authors: Kaufman Robert
Published: December 2008

A problem in descriptive set theory, in which the objects of interest are compact convex sets in linear metric spaces, primarily those having extreme points.
On (n, k, l, Δ)-systems
Authors: Cohen Stephen D. , Kuzjurin Nikolai N.
Published: December 2008

The paper is devoted to studying one generalization of Steiner systems S(n, k, l) closely related to packings and coverings of l-tuples by k-tuples of an n-set. One necessary and one sufficient condition for the existence of such designs are obtained.
Irreducible locally nilpotent finitary skew linear groups
Authors: Wehrfritz B. A. F.
Published: December 2008

Let V be a left vector space over the arbitrary division ring D and G a locally nilpotent group of finitary automorphisms of V (automorphisms g of V such that dimDV(g-1)<∞) such that V is irreducible as D-G bimodule. If V is infinite dimensional we show that such groups are very rare, much rarer than in the finite-dimensional case. For example we show that if dimDV is infinite then dimDV = |G| = ℵ0 and G is a locally finite q-group for some prime q ≠ char D. Moreover G is isomorphic to a finitary linear group over a field. Examples show that infinite-dimensional such groups G do exist. Note also that there exist examples of finite-dimensional such groups G that are not isomorphic to any finitary linear group over a field. Generally the finite-dimensional examples are more varied.
Asymptotic distribution of the zeros of certain Lagrange interpolants
Authors: Bokhari M. A. , Iqbal M.
Published: December 2008

We consider rational functions of the form fm(z) = zm/(z – p) which are analytic in |z|
1, and establish that the asymptotic distribution of the zeros of their Taylor sections and Lagrange interpolants at uniformly distributed nodes is similar. This notion is also illustrated computationally. We conjecture that a similar result can be expected for any function analytic in |z| < p.
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.
An estimate of sectional curvatures of hypersurfaces with positive Ricci curvatures
Authors: Kim Ju Seon , Kim Sang Og
Published: December 2008

Let M be a hypersurface in Euclidean space and let the Ricci curvature of M be bounded below by some nonnegative constant. In this paper, we estimate the sectional curvature of M in terms of the lower bound of Ricci curvature and the upper bound of mean curvature.
Unstable invariant distributions for a class of stochastic delay equations
Authors: Mohammed S. E. A.
Published: December 2008

In our article [8] we examined asymptotic mean square stability for linear retarded f.d.e.'s which are perturbed by white noise. It is shown in [8] and [10] that if the deterministic linear retarded f.d.e. is asymptotically stable, then so is the perturbed stochastic f.d.e.
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 problem

can 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).