bluuebunny/crossref_metadata_2025 huggingface dataset:
Tuning the absorption spectra and nonlinear optical properties of D‐π‐A azobenzene derivatives by changing the dipole moment and conjugation length: a theoretical study
Authors: Liu Zeyu , Lu Guo‐Yuan , Ma Jing
Published: October 2010

The optical properties of several azobenzene derivatives were modulated by varying the dipole moments and conjugation lengths of the D‐π‐A systems. The relationship between the structure and absorption spectrum and polarizability was studied in the gas phase, THF and MeOH solutions, respectively, by using the density functional theory. The calculated absorption spectra and second‐order polarizabilities are in good agreement with the available experimental observations. In comparison with the D‐π‐A monomer, the H‐shaped D‐π‐A dimer almost doubles the dipole moments and hence increases the second‐order polarizabilities, without a significant shift in the maximum absorption bands. The addition of another azobenzol group between electron‐donating and ‐accepting groups increases the second‐order polarizabilities by 4–6 times, but leads to an evident red‐shift of about 65–80 nm in spectra. The relative second‐order polarizability of the halogen‐substituted derivatives is in the sequence of CF3 > F > Cl > Br, without obvious substituent effects on the optical transparency. The D‐π‐A chromophores with the strong electron‐donating (amino) and ‐accepting (acetyl) substituent present the larger second‐order polarizabilities, at the cost of about 20 nm red‐shift of the maximum absorption lengths relative to the halogen‐substituted species. It is also demonstrated that both the linear and nonlinear optical properties augment with the increase in solvent polarity, accompanied by a red‐shift in the wavelengths of maximum absorption by about 18 and 23 nm, respectively, in THF and MeOH solutions. The changes in optical properties upon the structural modifications are further rationalized by the electronic structures of various H‐shaped dimers. Copyright © 2010 John Wiley & Sons, Ltd.
Alternating copolymers of 2,6‐bis(p‐dihexylaminostyryl)anthracene‐9,10‐diyl and N‐octylcarbazole with large two‐photon cross sections
Authors: Xueheng Zhang , Wen Li , Xiaojing Li , Tongliang Liu , Zhaobo Fan , Wenjun Yang
Published: October 2010

We report the synthesis, thermal, one‐ and two‐photon properties of poly(2,6‐bis(p‐dihexylaminostyryl)anthracene‐9,10‐diyl‐alt‐N‐octylcarbazole‐3,6‐/2,7‐diyl) (P1/P2). The as‐synthesized polymers exhibit number‐average molecular weights of 1.7 × 104 for P1 and 2.1 × 104 g/mol for P2. They emit strong one‐ and two‐photon excitation fluorescence with the peak around 502 nm, and the fluorescence quantum yields around 0.76 in chloroform. In film state, P1 and P2 show different red‐shift emission with the peaks at 512 nm and 523 nm, respectively. The DSC measurement reveals that as‐synthesized polymers are all amorphous aggregates with the glass transition temperatures of 131 °C for P1 and 152 °C for P2. The solution two‐photon absorption (TPA) properties of P1 and P2 in chloroform are measured by the two‐photon‐induced fluorescence method using femtosecond laser pulses (120 fs). The TPA cross sections (δ) are measured over the range of 700–900 nm. The maximal δ of P1 and P2 all appear at ∼800 nm and are 1010 GM and 940 GM per repeating unit, respectively. This suggests that no notable interactions among structure units that impair their fluorescence and TPA properties, and the polymers with large δ can be obtained by using the high TPA‐active units as building blocks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Stereospecific radical polymerization of N‐tert‐butoxycarbonylacrylamide in the presence of fluorinated alcohols
Authors: Hirano Tomohiro , Yamaoka Ryosuke , Miyazaki Takamasa , Ute Koichi
Published: October 2010

Radical polymerization of N‐tert‐butoxycarbonylacrylamide (NBocAAm) in toluene at low temperatures in the presence of the fluorinated alcohols, 2,2,2‐trifluoroethanol, 1,1,1,3,3,3‐hexafluoro‐2‐propanol, and nonafluoro‐tert‐butanol, afforded atactic, heterotactic, and syndiotactic polymers, respectively. NMR analysis revealed that the fluorinated alcohols formed hydrogen bonding‐assisted complexes with NBocAAm, with different structures. The difference in the structures of the complexes was responsible for the differences in the induced stereospecificities. Based on the structures of the complexes between NBocAAm and the fluorinated alcohols, mechanisms for the three kinds of stereospecific radical polymerizations are proposed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Methods for removal of residual catalyst from polymers prepared by ring opening metathesis polymerization
Authors: Lambeth Robert H. , Pederson Samuel J. , Baranoski Myvan , Rawlett Adam M.
Published: October 2010

Methods for removing the residual Grubbs' third generation catalyst from polymers prepared by ring opening metathesis polymerization are reported. Two strategies were investigated for reduction of the residual catalyst in the final polymer product. The first strategy involved the use of heterogeneous functionalized particles to scavenge the catalyst from the solution. Filtration of the particles followed by precipitation produced polymers with 10–60 ppm residual catalyst, depending on the type of particle used, surface functional groups, and number of equivalents. The second strategy used small organic molecules that could coordinate to the metal species and modify the solubility of the catalyst, facilitating partitioning of the catalyst into the precipitation solvent. Several types of molecules with varied functionality reduced the residual catalyst level to 30–120 ppm, depending on the loading. Hydrogenation of the polymer backbone followed by precipitation lowered the residual Ru content from 195 ppm to 10 ppm, suggesting that the difficulty of completely removing the catalyst could be a result of coordination of the metal species to the double bonds in the polymer backbone. Reducing the amount of trace catalyst significantly improved the oxidative stability of the polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Grafting polymerization of styrene onto alternating terpolymers based on chlorotrifluoroethylene, hexafluoropropylene, and vinyl ethers, and their modification into ionomers bearing ammonium side‐groups
Authors: Valade David , Boschet Frédéric , Ameduri Bruno
Published: October 2010

The grafting polymerization of styrene initiated by the alkyl chloride groups of poly(CTFE‐alt‐VE) and poly[(CTFE‐alt‐VE)‐co‐(HFP‐alt‐VE] copolymers (where CTFE, HFP, and VE stand for chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), and vinyl ether (VE), respectively) followed by the chemical modification of the polystyrene grafts are presented. First, the fluorinated alternating copolymers were produced by radical copolymerization of CTFE (with HFP) and VE. Second, atom transfer radical polymerization enabled the grafting polymerization of styrene in the presence of the poly(CTFE‐alt‐VE)‐macroinitiator using the alkyl chloride group of CTFE as the initiation site. Kinetics of the styrene polymerization indicated that such a grafting had a certain controlled character. For the first time, grafting of polystyrene onto alternating fluorinated copolymers has been achieved. Differential scanning calorimetry thermograms of these graft copolymers exhibited two glass transition temperatures assigned to both amorphous domains of the polymeric fluorobackbone (ranging from −20 to +56 °C) and the polystyrene grafts (ca. 95 °C). The thermostability of these copolymers increased on grafting. Thermal degradation temperatures at 5% weight loss were ranging from 193 to 305 °C when the polystyrene content varied from 81 to 27%. Third, chloromethylation of the polystyrene grafts followed by the cationization of the chloromethyl dangling groups led to original ammonium‐containing graft copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Synthesis and characterization of novel low‐bandgap triphenylamine‐based conjugated polymers with main‐chain donors and pendent acceptors for organic photovoltaics
Authors: Sahu Duryodhan , Padhy Harihara , Patra Dhananjaya , Huang Jen‐hsien , Chu Chih‐wei , Lin Hong‐Cheu
Published: October 2010

A series of novel low‐bandgap triphenylamine‐based conjugated polymers (PCAZCN, PPTZCN, and PDTPCN) consisting of different electron‐rich donor main chains (N‐alkyl‐2,7‐carbazole, phenothiazine, and cyclopentadithinopyrol, respectively) as well as cyano‐ and dicyano‐vinyl electron‐acceptor pendants were synthesized and developed for polymer solar cell applications. The polymers covered broad absorption spectra of 400–800 nm with narrow optical bandgaps ranging 1.66–1.72 eV. The highest occupied molecular orbital and lowest unoccupied molecular orbital levels of the polymers measured by cyclic voltammetry were found in the range of −5.12 to −5.32 V and −3.45 to −3.55 eV, respectively. Under 100 mW/cm2 of AM 1.5 white‐light illumination, bulk heterojunction photovoltaic devices composing of an active layer of electron‐donor polymers (PCAZCN, PPTZCN, and PDTPCN) blended with electron‐acceptor [6,6]‐phenyl‐C61‐butyric acid methyl ester or [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM) in different weight ratios were investigated. The photovoltaic device containing donor PCAZCN and acceptor PC71BM in 1:2 weight ratio showed the highest power conversion efficiency of 1.28%, with Voc = 0.81 V, Jsc = 4.93 mA/cm2, and fill factor = 32.1%. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Stimulated emission and ultrafast optical switching in a ter(9,9′‐spirobifluorene)‐co‐methylmethacrylate copolymer
Authors: Charas Ana , Mendonça A. Luísa , Clark Jenny , Bazzana Luca , Nocivelli Alessandro , Lanzani Guglielmo , Morgado Jorge
Published: October 2010

A methacrylate‐functionalized 9,9′‐spirobifluorene trimer is copolymerized with methylmethacrylate (MMA). The photophysical characterization of this copolymer using pump‐probe studies, in solution, as films and in plastic optical fibers (POFs) demonstrates that it shows interesting photonic properties for data communication such as high‐stimulated emission cross section (σSE = 2.5 × 10−16 cm2), good thermal, and optical stability, the ability to perform all‐optical ultrafast switching, and low attenuation when doped into POFs. In addition, the material shows interesting optically induced conformational control in solution and the studies demonstrate the surprising result that intrachain polaron pairs can be generated even in well‐isolated 3‐unit oligomers. Although the material is not yet soluble enough in MMA to create highly efficient photonic devices and the gain spectrum is not optimized to overlap with the region of low attenuation in polymethylmethacrylate POFs, these studies are a good starting point to further optimize copolymers for incorporation into POF networks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010
The effect of annealing conditions on the intercalation and exfoliation of layered silicates in polymer nanocomposites
Authors: Ceccia Simona , Bellucci Federica , Monticelli Orietta , Frache Alberto , Traverso Giuliano , Casale Antonio
Published: October 2010

Layered silicate nanocomposites based on polyamide 6 and polypropylene have been prepared via static annealing experiments. The evolution of clay dispersion into the polymer matrices was monitored by wide angle X‐ray diffraction analysis and transmission electron microscopy. The results have evidenced that the polymer diffusion inside the organoclay galleries is spontaneous and have elucidated the mechanism of nanostructured system formation under static conditions. Indeed, the exfoliation mechanism turned to be a two‐step process consisting of polymer intercalation into the clay galleries and progressive layer delamination. Both steps have turned out to depend on thermodynamic and kinetic parameters. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010
Thermal properties and influence of orientation on crystalline morphologies in stereoblock polypropylene and related elastomers
Authors: Sauer Bryan B. , Kampert William G. , Mclean R. Scott , Monteiro Raisa
Published: October 2010

Atomic force microscopy (AFM), small angle X‐ray scattering (SAXS), temperature modulated differential scanning calorimetry (TMDSC), variable heating rate DSC, an independent rapid heating rate method for melting points, and cyclic mechanical testing were used to study semicrystalline thermoplastic elastomeric polypropylenes (ELPPs) and related semicrystalline polyolefins including ethylene copolymers. Low crystallinity (ca., 9 and 15%) ELPP samples were studied by AFM in the nonoriented and melt‐oriented states. AFM images taken as a function of time after quenching of a melt‐drawn and highly nucleated film resolved details of secondary crystallization involving lateral growth on the ordered row‐nucleated structures. For nonoriented films, isothermal melt crystallization at high temperatures (110 °C) led to similar features for the two ELPPs. The dominant crystalline morphology studied by AFM consisted of small (several nm in width) granular crystallites organized into immature but large spherulites spanning tens of microns. A striking cross‐hatch morphology was detected in regions of the surface in 110 °C crystallized samples, which is contrasted with melt‐drawn films where row nucleated structures dominated the morphology in the film under no external stress. AFM was also used to monitor the morphological changes that occurred as the films were stretched at 25 °C. Break‐down of lamellae was observed, resulting in oriented narrow fibrils. Cyclic stress‐strain curves showed the expected result where lower crystallinity ELPPs had higher recoverable levels of set after both 100 and 500% elongation. TMDSC was used to resolve the broad melting and recrystallization regions in these low to medium crystallinity ELPP systems, and to contrast the results with ethylene copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Generalized geometry and partial supersymmetry breaking
Authors: Triendl H.
Published: October 2010

This review article consists of two parts. In the first part we use the formalism of (exceptional) generalized geometry to derive the scalar field space of SU(2) × SU(2)‐structure compactifications. We show that in contrast to SU(3) × SU(3) structures, there is no dynamical SU(2) × SU(2) structure interpolating between an SU(2) structure and an identity structure. Furthermore, we derive the scalar manifold of the low‐energy effective action for consistent Kaluza‐Klein truncations as expected from 𝒩 = 4 supergravity. In the second part we then determine the general conditions for the existence of stable Minkowski and AdS 𝒩=1 vacua in spontaneously broken gauged 𝒩 = 2 supergravities and construct the general solution under the assumption that two appropriate commuting isometries exist in the hypermultiplet sector. Furthermore, we derive the low‐energy effective action below the scale of partial supersymmetry breaking and show that it satisfies the constraints of 𝒩 = 1 supergravity. We then apply the discussion to special quaternionic‐Kähler geometries which appear in the low‐energy limit of SU(3) × SU(3)‐structure compactifications and construct Killing vectors with the right properties. Finally we discuss the string theory realizations for these solutions.
A course for clinical trial personnel in clinical study designs, randomization, allocation schedules, and interactive response systems
Authors: Golm Gregory T. , Bradstreet Thomas E. , Coffey Laura A.
Published: October 2010

This continuing education course for professionals involved in all areas of clinical trials integrates concepts related to the role of randomization in the scientific process. The course includes two interactive lecture and discussion sections and a workshop practicum. The first interactive lecture introduces basic clinical trial issues and statistical principles such as bias, blinding, randomization, control groups, and the importance of formulating clear and discriminating clinical and statistical hypotheses. It then focuses on the most commonly used clinical study designs and the corresponding patient randomization schemes. The second interactive lecture focuses on the implementation of randomization of patients and drug supply through allocation and component ID schedules. The workshop practicum, conducted in small groups, enables students to apply the lecture concepts to real clinical studies. Flexibility was built into the workshop practicum materials to allow the course content to be customized to specific audiences, and the interactive lecture sessions can be stretched to cover more advanced topics according to class interest and time availability. Copyright © 2010 John Wiley & Sons, Ltd.
Review of the statistical analysis of the dog telemetry study
Authors: Aylott Mike , Bate Simon , Collins Susie , Jarvis Philip , Saul Jim
Published: October 2010

In 2008, the PSI Toxicology Special Interest Group met to discuss the design and analysis of dog telemetry studies. The dog telemetry study is one component of the integrated cardiovascular assessment required by regulatory bodies. Although there are guidelines for these studies, little is said about the statistical analysis. With parameters of interest measured continually over time, in studies typically involving four dogs, the analysis is not straightforward. This has led to many different types of analysis being proposed in the literature, with many different methods applied within the pharmaceutical industry itself. This paper summarizes the PSI Toxicology group's discussions and recommendations around these issues. Copyright © 2010 John Wiley & Sons, Ltd.
Usage space analysis for reliability testing
Authors: Haselgruber Nikolaus , Mautner Karin , Thiele Jan
Published: October 2010

During the development process of a complex technical product, one widely used and important technique is accelerated testing where the applied stress on a component is chosen to exceed the reference stress, i.e. the stress encountered in field operation, in order to reduce the time to failure. For that, the reference stress has to be known. Since a complex technical product may fail regarding numerous failure modes, stress in general is highly dimensional rather than scalar. In addition, customers use their products individually, i.e. field operation should be described by a distribution rather than by one scalar stress value. In this paper, a way to span the customer usage space is shown. It allows the identification of worst case reference stress profiles in significantly reduced dimensions with minimal loss of information. The application example shows that even for a complex product like a combustion engine, stress information can be compressed significantly. With low measurement effort it turned out that only three reference stress cycles were sufficient to cover a broad range of customer stress variety. Copyright © 2010 John Wiley & Sons, Ltd.
Bag‐of‐words‐driven, single‐camera simultaneous localization and mapping
Authors: Botterill Tom , Mills Steven , Green Richard
Published: October 2010

This paper describes BoWSLAM, a scheme for a robot to reliably navigate and map previously unknown environments, in real time, using monocular vision alone. BoWSLAM can navigate challenging dynamic and self‐similar environments and can recover from gross errors. Key innovations allowing this include new uses for the bag‐of‐words image representation; this is used to select the best set of frames from which to reconstruct positions and to give efficient wide‐baseline correspondences between many pairs of frames, providing multiple position hypotheses. A graph‐based representation of these position hypotheses enables the modeling and optimization of errors in scale in a dual graph and the selection of only reliable position estimates in the presence of gross outliers. BoWSLAM is demonstrated mapping a 25‐min, 2.5‐km trajectory through a challenging and dynamic outdoor environment without any other sensor input, considerably farther than previous single‐camera simultaneous localization and mapping (SLAM) schemes. © 2010 Wiley Periodicals, Inc.
Galileo/SAR: Performance aspects and new service capabilities
Authors: Lewandowski Andreas , Niehoefer Brian , Wietfeld Christian
Published: October 2010

The European satellite navigation system Galileo is a highly promising technology and offers communication capabilities that can be bridled to provide an enhanced Search‐and‐Rescue (SAR) service in combination with the system, currently in service, Cospas‐Sarsat. In order to enhance the process of retrieval during a rescue operation, this article proposes a Short Messaging Service (SMS) by utilizing the existing message formats and owes of the SAR service. Architectural building blocks which are particularly belonging to either Cospas‐Sarsat or Galileo are highlighted. A new simulation method for local 3D scenarios is presented, which combines detailed 3D environment models with ray tracing and event‐based protocol simulation. Results, both in a global and local 3D setup, reflect the performance indicators of the satellite systems from which the achievable service quality of SAR‐SMS is deduced. The necessity of Galileo/SAR for highly reliable and fast applications in emergency situations is shown and a minimum number of Galileo satellites carrying SAR payload is derived. Copyright © 2010 John Wiley & Sons, Ltd.
Dual polarization MIMO in LMS broadcasting systems: Possible benefits and challenges
Authors: Arapoglou Pantelis‐Daniel , Zamkotsian Martin , Cottis Panayotis
Published: October 2010

The benefits of employing dual polarization in wireless multiple‐input multiple‐output (MIMO) communication systems are only recently becoming apparent due to the continuous measurement and modeling efforts by the terrestrial research community. Land mobile satellite (LMS) broadcasting systems exhibit distinct channel, system and geometrical characteristics and are subjected to stringent spatial limitations compared to terrestrial wireless. Therefore, it remains to be investigated which operating conditions favor the joint instead of the independent encoding/decoding over the two polarizations of satellite beams. After outlining the relevant progress made in wireless dual polarization MIMO systems, the present work carries out a thorough comparison between the joint and independent encoding/decoding approaches in typical single‐satellite LMS systems exploiting state‐of‐the‐art building blocks. This comparative analysis investigates both the capacity and error performance under a fair framework between systems occupying the same resources. Since the same analytical tools are used for both terrestrial and satellite dual polarization systems, the present paper may also serve as an analytical bridge between the two. Copyright © 2010 John Wiley & Sons, Ltd.
Study on advanced nanoscale near‐field photolithography
Authors: Yang Ching‐Been , Chiang Hsiu‐Lu , Huang Jen‐Ching
Published: October 2010

At present, applying a near‐field optical microscope to photolithographic line segment fabrication can only obtain nanoscale line segments of equal cutting depths, and cannot result in 3D shape fabrication. This study proposes an innovative line segment fabrication model of near‐field photolithography that adjusts an optical fiber probe's field distance to control the exposure energy density, and moreover constructs an exposure energy density analysis method of the innovative photolithographic line segment fabrication. During the exposure simulation process of the innovative line segment fabrication model of near‐field photolithography, the near‐field distance between the optical fiber probe and the photoresist surface increases gradually, whereas the exposure energy density distribution decreases gradually. As a result, the cutting depth becomes shallower and the full‐width at half maximum (FWHM) increases. The results of this study can serve as a theoretical reference for developing advanced nanoscale near‐field photolithography techniques, to which an important and groundbreaking contribution is made. SCANNING 32: 351–360, 2010. © 2010 Wiley Periodicals, Inc.
Evolution of ZDDP‐derived reaction layer morphology with rubbing time
Authors: Naveira‐Suarez A. , Tomala A. , Pasaribu R. , Larsson R. , Gebeshuber I. C.
Published: October 2010

Functional additives, particularly extreme pressure and antiwear additives, in formulated oil will compete to adsorb and function in tribological contacts. A low‐polarity commercial base oil, poly‐α‐olefin (PAO), blended with zinc dialkyl dithiophosphates (ZDDP) has been studied. The tribological performance was evaluated using a ball‐on‐disk test rig under mixed rolling–sliding conditions in the boundary lubrication regime at 90°C. An adapted in situ interferometry technique was used to monitor the additive‐derived reaction layer formation. The thickness of the reaction layer evolves with rubbing until reaching a limiting thickness value of approximately 70 nm. The evolution of the topography and mechanical properties of the ZDDP‐derived reaction layer with rubbing time were studied using Atomic Force Microscopy. A constant roughening and hardening of the additive‐derived layer with rubbing time is observed and related to the different tribological performance of the layer at different rubbing times. SCANNING 31: 294–303, 2010. © 2010 Wiley Periodicals, Inc.
Security of the GPT cryptosystem and its applications to cryptography
Authors: Rashwan Haitham , Gabidulin Ernst M. , Honary Bahram
Published: October 2010

The public key cryptosystem (PKC) based on rank error correcting codes (the GPT cryptosystem) was proposed in 1991. Use of rank codes in cryptographic applications is advantageous since it is practically impossible to utilize combinatoric decoding. This enabled using public keys of a smaller size. Several attacks against this system were published, including Gibson's attacks and more recently Overbeck's attacks. A few modifications were proposed withstanding Gibson's attack but at least one of them was broken by the stronger attacks by Overbeck. A tool to prevent Overbeck's attack is presented by Gabidulin, which makes the cryptographer define a proper column scrambler matrix over the extension field without violating the standard mode of GPT cryptosystem. In this paper, we apply this tool to another variant of the GPT cryptosystem. Furthermore we increase the security of the proposed system against all known attacks and reduce the public key size to 4 Kbits instead of 10 Kbits. Copyright © 2010 John Wiley & Sons, Ltd.
Palmprint authentication using fusion of wavelet and contourlet features
Authors: Prasad S. M. , Govindan V. K. , Sathidevi P. S.
Published: October 2010

Low resolution palmprint images consist of discriminative multisized and multidirectional principal lines and wrinkles. Intuitively, discrete wavelet transform (DWT) is a good choice to extract such patterns due to its space‐frequency localization, multiresolution analysis (MRA) capability, and computational efficiency. However, most of the DWT‐based palmprint recognition systems fail to report low equal error rate (EER) due to inherent limitations of DWT and shift‐rotational variations in the intraclass palmprint images. This paper proposes the techniques for shift and rotation invariant feature extraction using DWT extension. The effectiveness of these techniques is tested on deliberately shifted and rotated palmprints. Further, limited directionality due to DWT is overcome by augmenting with features of contourlet transform. Contourlet transform can extract curve singularities effectively with multidirectional decomposition capability; wavelets are good in extracting point singularities. The different views of contourlet transform and DWT on palmprints motivate us to extract contourlet and wavelet features, and examine them for their individual and combined verification performances. The combined mode is found to perform well over their individual performances. The average EER (0.41%), obtained on PolyU‐Online‐Palmprint‐Database‐II (PolyU), is better than the existing wavelets/transform‐based palmprint recognition approaches and comparable to the other state of the art palmprint recognition approaches. The computational burden on feature extraction and matching is substantially low thereby making the approach suitable for resource constrained environments. Copyright © 2010 John Wiley & Sons, Ltd.
Repression of Mammary Stem/Progenitor Cells by p53 Is Mediated by Notch and Separable from Apoptotic Activity
Authors: Tao Luwei , Roberts Amy L. , Dunphy Karen A. , Bigelow Carol , Yan Haoheng , Jerry D. Joseph
Published: October 2010

Breast cancer is the most common tumor among women with inherited mutations in the p53 gene (Li-Fraumeni syndrome). The tumors represent the basal-like subtype, which has been suggested to originate from mammary stem/progenitor cells. In mouse mammary epithelium, mammosphere-forming potential was increased with decreased dosage of the gene encoding the p53 tumor suppressor protein (Trp53). Limiting dilution transplantation also showed a 3.3-fold increase in the frequency of long-term regenerative mammary stem cells in Trp53−/− mice. The repression of mammospheres by p53 was apparent despite the absence of apoptotic responses to radiation indicating a dissociation of these two activities of p53. The effects of p53 on progenitor cells were also observed in TM40A cells using both mammosphere-forming assays and the DsRed-let7c-sensor. The frequency of long-term label-retaining epithelial cells was decreased in Trp53−/− mammary glands indicating that asymmetric segregation of DNA is diminished and contributes to the expansion of the mammary stem cells. Treatment with an inhibitor of γ-secretase (N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester) reduced the number of Trp53−/− mammospheres to the level found in Trp53+/+ cells. These results demonstrate that basal levels of p53 restrict mammary stem/progenitor cells through Notch and that the Notch pathway is a therapeutic target to prevent expansion of this vulnerable pool of cells.
Postnatal manganese exposure alters the expression of D2L and D2S receptor isoforms: Relationship to PKA activity and Akt levels
Authors: Mcdougall Sanders A. , Der‐Ghazarian Taleen , Britt Cynthia E. , Varela Fausto A. , Crawford Cynthia A.
Published: October 2010

Postnatal manganese chloride (Mn) exposure causes persistent changes in presynaptic dopamine (DA) functioning (e.g., Mn reduces DA transporter levels and DA uptake), but evidence that Mn affects postsynaptic DA receptors and their associated second messenger systems is equivocal. Therefore, a goal of the present study was to determine whether exposing rats to Mn on postnatal days (PD) 1‐21 would cause long‐term alterations in D2 long (D2L) and D2 short (D2S) receptors that were detectible in adulthood (i.e., on PD 90). Signaling systems associated with D2 receptors were also assessed. Specifically, we measured protein kinase A (PKA) activity in the dorsal striatum and prefrontal cortex (PFC), whereas immunoblotting was used to quantify phosphorylated Akt (p‐Akt) and phosphorylated ERK. Results showed that early Mn exposure caused a persistent elevation of D2L and D2S protein expression in the dorsal striatum, as well as an increase in the number of D2 binding sites. Conversely, Mn reduced D2 specific binding in the PFC on PD 90. PKA activity of Mn‐treated rats was enhanced in both the dorsal striatum and PFC, whereas p‐Akt levels were elevated in the dorsal striatum. When considered together, these results suggest that postnatal Mn exposure either directly or indirectly alters the functioning of postsynaptic DA receptors. One possibility is that early Mn exposure depresses presynaptic dopaminergic functioning and reduces DA levels, thereby causing an up‐regulation of D2 receptors and a dysregulation of DA‐associated signaling pathways. An alternative explanation is that early Mn exposure affects D2 receptors and PKA/p‐Akt levels via independent mechanisms. Synapse, 2011. © 2010 Wiley‐Liss, Inc.
Do we have what it takes to put all students on the graduation path?
Authors: Legters Nettie , Balfanz Robert
Published: October 2010

According to current estimates, more than a quarter of all students and over 40 percent of African American and Hispanic students do not graduate from high school on time. The vast majority of those young people who do not graduate with their peers drop out. The enormous costs to these individuals, their communities, and our society require us to invest in systems that accurately identify young people at risk of dropping out and provide the supports necessary to keep them on track to graduation. This chapter offers a framework for action that calls on communities to identify the scale and scope of the dropout problem and understand why students disengage from school; transform or replace low‐performing schools; install early warning and multitiered response systems that provide comprehensive, targeted, and intensive supports to students in and out of school; establish supportive policies and resource allocations; and build community will and capacity so positive changes are deeply implemented and sustained.
The new dropout challenge: Bridging gaps among students, parents, and teachers
Authors: Bridgeland John M.
Published: October 2010

Interview and survey data reveal significant disconnects among the insights and perspectives of dropouts, parents, teachers, and administrators on the causes and solutions to the dropout challenge. Many educators, for example, do not see boredom as a factor for most dropouts, while young people who drop out see it as the central cause. The author argues that if these disconnects are not more fully understood and bridged, they will continue to set back efforts to keep more students in school and on track to graduate ready for postsecondary education. Models for how communities can engage these constituencies in productive dialogue and transformative action are included in reports and in Grad Nation, a guidebook that helps communities tackle their dropout crises.
A greater society: The transformation of the federal role in education
Authors: Wise Bob , Rothman Robert
Published: October 2010

The federal role in education will soon be transformed in ways that could produce an even greater society than President Lyndon B. Johnson envisioned. The authors identify underlying principles of this new role and describe how it represents a significant departure from the past. Historically, for example, the federal government has been prescriptive about the kinds of practices that states and districts must adopt as a condition of receiving federal funds, but it has not specified outcomes. Under the new approach, the federal government would specify the goals and outcomes while allowing states, districts, and schools flexibility in how they use federal funds to innovate and adopt best practices. The authors argue for immediate action. Every day of delay, they note, yields another seven thousand dropouts and leaves schools and communities without the tools and resources that can help turn the situation around.
Predator‐recognition training: a conservation strategy to increase postrelease survival of hellbenders in head‐starting programs
Authors: Crane Adam L. , Mathis Alicia
Published: October 2010

For species with declining populations, captive rearing with subsequent release into natural habitats (“head‐starting”) is often used as part of a conservation strategy. One challenge to head‐starting programs is that head‐started individuals can suffer high rates of postrelease predation. Head‐starting programs are currently being established for hellbenders (Cryptobrancus alleganeinsis), large aquatic salamanders that are experiencing population declines throughout much of the species' range. Although hellbenders have innate recognition of many predators, inexperienced juveniles show only weak recognition of introduced trout. We used a classical conditioning protocol to train captive‐reared hellbender larvae to show fright responses to the scent of trout. We exposed hellbender larvae to trout‐scented water plus a hellbender distress secretion during training trials. In a subsequent test, these larvae responded to trout cues alone with a fright response; control larvae that were trained with the trout scent plus a blank control did not show a fright response to the trout cues. Learning was specific to trout because trained larvae did not respond to water that had been scented by a suckermouth catfish. Although a number of details remain to be addressed concerning standardized procedures, we recommend that head‐starting programs for hellbenders include trout‐recognition training. Zoo Biol 30:611–622, 2011. © 2010 Wiley Periodicals, Inc.
The developmental association of sexual self‐concept with sexual behavior among adolescent women
Authors: Hensel Devon J. , Fortenberry J. Dennis , O'Sullivan Lucia F. , Orr Donald P.
Published: October 2010

Developing a sexual self‐concept is an important developmental task of adolescence; however, little empirical evidence describes this development, nor how these changes are related to development in sexual behavior. Using longitudinal cohort data from adolescent women, we invoked latent growth curve analysis to: (1) examine reciprocal development in sexual self‐concept (sexual openness, sexual esteem and sexual anxiety) over a four year time frame; (2) describe the relationship of these trajectories with changes in sexual behavior. We found significant transactional effects between these dimensions and behavior: sexual self‐concept evolved during adolescence in a manner consistent with less reserve, less anxiety and greater personal comfort with sexuality and sexual behavior. Moreover, we found that sexual self‐concept results from sexual behavior, as well as regulates future behavior.
Interaction between separated consecutive complement control modules of human C1r: Implications for dimerization of the full‐length protease
Authors: Láng András , Major Balázs , Szilágyi Katalin , Gáspári Zoltán , Gál Péter , Závodszky Péter , Perczel András
Published: October 2010

MINT‐8045767: CCP1 (uniprotkb:P00736) and CCP2 (uniprotkb:P00736) bind (MI:0407) by nuclear magnetic resonance (MI:0077)
Association of Shoulder Pain With the Use of Mobility Devices in Persons With Chronic Spinal Cord Injury
Authors: Jain Nitin B. , Higgins Laurence D. , Katz Jeffrey N. , Garshick Eric
Published: October 2010

Objective

To assess the prevalence of shoulder pain and its association with the use of assistive devices for mobility in persons with chronic spinal cord injury (SCI).

Design

Cross‐sectional analysis conducted within a cohort study.

Setting

SCI service in a hospital and the community.

Participants

Between August 2005 and January 2008, 93 participants with chronic SCI completed a standardized health questionnaire and pain questionnaire.

Main Outcome Measures

Shoulder pain in last 6 months elicited by use of the McGill Pain Questionnaire pain diagram.

Results

Of the 93 participants, 65 (69.9%) reported pain at any site in the 6 months before testing. Shoulder pain, reported by 39.8% of participants, was the third most common site of pain after the legs and back. When stratified by the use of assistive mobility devices, shoulder pain was reported by 46.7% of motorized wheelchair users, 35.4% of manual wheelchair users, 47.6% of participants using aids such as crutch(es) or canes, and 33.3% of participants walking without assistance (P = .7 for comparison of 4 groups).

Conclusions

Shoulder pain is highly prevalent in SCI. The authors of previous studies have largely attributed shoulder pain in SCI to manual wheelchair use. However, our results provide evidence for similarly elevated prevalence of shoulder pain among motorized wheelchair users and those patients using crutches or canes. This finding suggests that in addition to overuse injury from cyclic wheelchair propulsion, the assessment of other mechanical and nonmechanical factors that lead to shoulder pain in SCI is an unmet research need that may have treatment implications.
Evaluating the Relationship of Calcium and Vitamin D in the Prevention of Stress Fracture Injuries in the Young Athlete: A Review of the Literature
Authors: Tenforde Adam S. , Sayres Lauren C. , Sainani Kristin L. , Fredericson Michael
Published: October 2010

Calcium and vitamin D are recognized as 2 components of nutrition needed to achieve and maintain bone health. Calcium and vitamin D have been clearly shown to improve bone density and prevent fractures at all ages. However, the literature is conflicting as to the role of these nutrients in young athletes ages 18 to 35 years, both for bone development and for the prevention of bone overuse injuries. Differences in findings may relate to study design. Although retrospective and cross‐sectional studies have had mixed results, the authors of prospective studies have consistently demonstrated a relationship of increased calcium intake with an improvement in bone density and a decrease in fracture risk. A randomized trial in female military recruits demonstrated that calcium/vitamin D supplementation reduced the incidence of stress fractures. A prospective study in young female runners demonstrated reduced incidence of stress fractures and increased bone mineral density with increased dietary calcium intake. Findings from both studies suggest female athletes and military recruits who consumed greater than 1500 mg of calcium daily exhibited the largest reduction in stress fracture injuries. To date, no prospective studies have been conducted in male athletes or in adolescent athletes. In most studies, males and nonwhite participants were poorly represented. Evidence regarding the relationship of vitamin D intake with the prevention of fractures in athletes is also limited. More prospective studies are needed to evaluate the role of calcium and vitamin D intake in prevention of stress fracture injuries in both male and female adolescent athletes, particularly those participating in sports with greater incidences of stress fracture injury.
A Randomized Controlled Trial of Exercise to Improve Mood After Traumatic Brain Injury
Authors: Hoffman Jeanne M. , Bell Kathleen R. , Powell Janet M. , Behr James , Dunn Erin C. , Dikmen Sureyya , Bombardier Charles H.
Published: October 2010

Objective

To test the hypothesis that a structured aerobic exercise regimen would decrease the severity of depressive symptoms in people with traumatic brain injury (TBI) who reported at least mild depression severity at baseline.

Design

Prospective, randomized, controlled trial.

Setting

Community gymnasium.

Participants

Subjects with a history of a prior TBI (6 months to 5 years post‐injury), recruited from the community. Inclusion criteria included scoring ≥5 on the Patient Health Questionnaire‐9. Subjects were excluded if they were non‐English speakers, had a medical condition precluding exercise, had suicidal ideation, regularly exercised, or could not use standard aerobic exercise equipment.

Intervention

Weekly supervised exercise sessions over a 10‐week period consisted of education, warm‐up, 30 minutes of aerobic exercise, and cool down. The exercise intensity was adjusted to reach a heart rate goal of 60% of the participant's estimated maximal heart rate.

Main Outcome Measurement

Beck Depression Inventory (BDI) comparing exercise to control groups. Post hoc analyses compared groups exercising ≥90 minutes or <90 minutes per week.

Results

Between‐group comparisons at 10 weeks revealed no difference between groups on the BDI (P = .250). For the groups divided by minutes exercised per week, the high‐activity group had significantly better depression scores than those in the low‐activity group (P = .033).

Conclusions

Although there was no statistically significant difference between the treated and the control group on mood after intervention, those persons with TBI who recounted higher levels of exercise per week also reported less depression and improved sleep, community participation, and overall quality of life.
Mining Gene Expression Profiles: An Integrated Implementation of Kernel Principal Component Analysis and Singular Value Decomposition
Authors: Reverter Ferran , Vegas Esteban , Sánchez Pedro
Published: October 2010

The detection of genes that show similar profiles under different experimental conditions is often an initial step in inferring the biological significance of such genes. Visualization tools are used to identify genes with similar profiles in microarray studies. Given the large number of genes recorded in microarray experiments, gene expression data are generally displayed on a low dimensional plot, based on linear methods. However, microarray data show nonlinearity, due to high-order terms of interaction between genes, so alternative approaches, such as kernel methods, may be more appropriate. We introduce a technique that combines kernel principal component analysis (KPCA) and Biplot to visualize gene expression profiles. Our approach relies on the singular value decomposition of the input matrix and incorporates an additional step that involves KPCA. The main properties of our method are the extraction of nonlinear features and the preservation of the input variables (genes) in the output display. We apply this algorithm to colon tumor, leukemia and lymphoma datasets. Our approach reveals the underlying structure of the gene expression profiles and provides a more intuitive understanding of the gene and sample association.
A multimodal method for liquid sloshing in a two-dimensional circular tank
Authors: FALTINSEN ODD M. , TIMOKHA ALEXANDER N.
Published: October 2010

Two-dimensional forced liquid sloshing in a circular tank is studied by the multimodal method which uses an expansion in terms of the natural modes of free oscillations in the unforced tank. Incompressible inviscid liquid, irrotational flow and linear free-surface conditions are assumed. Accurate natural sloshing modes are constructed in an analytical form. Based on these modes, the ‘multimodal’ velocity potential of both steady-state and transient forced liquid motions exactly satisfies the body-boundary condition, captures the corner-point behaviour between the mean free surface and the tank wall and accurately approximates the free-surface conditions. The constructed multimodal solution provides an accurate description of the linear forced liquid sloshing. Surface wave elevations and hydrodynamic loads are compared with known experimental and nonlinear computational fluid dynamics results. The linear multimodal sloshing solution demonstrates good agreement in transient conditions of small duration, but fails in steady-state nearly-resonant conditions. Importance of the free-surface nonlinearity with increasing tank filling is explained.
Transience to instability in a liquid sheet
Authors: BARLOW N. S. , HELENBROOK B. T. , LIN S. P.
Published: October 2010

Series solutions are found which describe the evolution to absolute and convective instability in an inviscid liquid sheet flowing in a quiescent ambient gas and subject to a localized perturbation. These solutions are used to validate asymptotic stability predictions for sinuous and varicose disturbances. We show how recent disagreements in growth predictions stem from assumptions made when arriving at the Fourier integral response. Certain initial conditions eliminate or reduce the order of singularities in the Fourier integral. If a Gaussian perturbation is applied to both the position and velocity of a sheet when the Weber number is less than one, we observe absolutely unstable sinuous waves which grow liket1/3. If only the position is perturbed, we find that the sheet is stable and decays liket−2/3at the origin. Furthermore, if both the position and velocity of a sheet are perturbed in theabsenceof ambient gas, we observe a new phenomenon in which sinuous waves neither grow nor decay and varicose waves grow liket1/2with a convective instability.