bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Characterization of Polyurethane‐Based Shape‐Memory Polymers for Tailored Tg around Body Temperature for Medical Applications
Authors: Ahmad Manzoor , Luo Jikui , Xu Bin , Purnawali Hendra , King Peter James , Chalker Paul Raymond , Fu Yongqing , Huang Weimin , Miraftab Mohsen
Published: January 2011

Various polyurethane‐based SMPUs were synthesized using five types of polyols as soft segments and two different diisocyanates as hard segments. The effects of diisocyanate concentration on material properties such as crystallinity, transition temperature, shape‐memory effect and tensile strength were investigated. SMPUs with a maximum strain near 1 000%, recovery rate up to ≈98%, fixity up to ≈90% and Tgs of 35–45 °C were obtained. A high MDI content results in SMPUs with better shape‐memory effect, whereas increasing IPDI content leads to a weaker shape‐memory effect. High IPDI concentration seems to prevent or restrict chemical reactions and crosslinks between the polyols and the hard segments, leading to large phase separation and coexistence of soft and hard segments in the macrophases.

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A Novel Bifunctional Trithiocarbonate for Styrene and Methacrylate RAFT Polymerization
Authors: Strube Oliver I. , Nothdurft Lars , Drache Marco , Schmidt‐Naake Gudrun
Published: January 2011

The synthesis of butane‐1,4‐bis(phenylacetonitrile trithiocarbonate) and its application as a new chain transfer agent for controlled radical polymerization is reported. It is a bifunctional trithiocarbonate for the polymerization of methacrylates, and styrenic monomers and therefore a novel type of RAFT agent. Linear growth of molar masses with conversion and narrow molecular weight distributions are obtained. ABA triblock copolymers are successfully synthesized in two steps. MALDI‐TOF MS and SEC prove the living character of the polymers and uniform growth of both functionalities. The pre‐equilibrium kinetics are analyzed by SEC to determine transfer coefficients. The P(GMA) blocks are used as precursor for polymer‐analogous reactions.

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Correlation of fractions with divisibility constraints
Authors: Xiong Maosheng , Zaharescu Alexandru
Published: January 2011

Let \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$ B=(B_{Q}\!)_{{Q \in {\mathbb N}}} $\end{document} be an increasing sequence of positive square free integers satisfying the condition that $ B_{{Q_1}}\vert B_{{Q_2}} $ whenever Q1 < Q2. For any subinterval I ⊂ [0, 1], let

It is shown that if BQ ≪ Qlog log Q/4, then the limiting pair correlation function of the sequence \documentclass{article}\usepackage{amsmath,amssymb,mathrsfs,bm}\pagestyle{empty}\begin{document}$ ({\mathscr{F}_{{B}\!,_Q}(I)})_{Q \in {\mathbb N}} $\end{document} exists and is independent of the subinterval I. Moreover, the sequence is Poissonian if $ \lim_{Q \rightarrow \infty }{{\varphi (B_{Q}\!)}\over{B_{Q}\!}} = 0 $, and exhibits a very strong repulsion if $ \lim_{Q \rightarrow \infty }{{\varphi (B_{Q}\!)}\over{B_{Q}\!}} \ne 0 $, where φ is Euler's totient function. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
Bounded Operators and Complemented Subspaces of Cartesian Products
Authors: Djakov P. , Terzioğlu T. , Yurdakul M. , Zahariuta V.
Published: January 2011

We study the structure of complemented subspaces in Cartesian productsX×Yof Köthe spacesXandYunder the assumption that every linear continuous operator fromXtoYis bounded. In particular, it is proved that each non‐Montel complemented subspace with absolute basisE⊂X×Yis isomorphic to a space of the formE1×E2, whereE1is a complemented subspace ofXandE2is a complemented subspace ofY. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
Independent linear forms on connected Abelian groups
Authors: Feldman Gennadiy , Myronyuk Margaryta
Published: January 2011

According to the classical Skitovich‐Darmois theorem the independence of two linear forms of independent random variables implies that the random variables are Gaussian. We prove an analog of this theorem for some locally compact Abelian groups. It turns out that in the considered case the random variables are either Gaussian or their distributions are convolutions of Gaussian distributions and some signed measures. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
Wnt antagonist DICKKOPF‐3 (Dkk‐3) induces apoptosis in human renal cell carcinoma
Authors: Ueno Koji , Hirata Hiroshi , Majid Shahana , Chen Yi , Zaman Mohd S. , Tabatabai Z. Laura , Hinoda Yuji , Dahiya Rajvir
Published: January 2011

The Wnt signaling pathway is activated in most cancers while Wnt antagonist genes are inactivated. However, the functional significance and mechanisms of inactivation of Wnt antagonist Dkk‐3 gene in renal cell carcinoma (RCC) has not been reported. In this study, we examined potential epigenetic mechanisms regulating Dkk‐3 expression in RCC cells and whether Dkk‐3 expression affects cell growth and apoptosis. The expression of Dkk‐3 is regulated by histone modification rather than CpG island DNA methylation in renal cancer cells. Renal cancer cell proliferation was significantly inhibited and apoptosis was promoted in Dkk‐3 transfected renal cancer cells. Dkk‐3 did not inhibit the Wnt/beta‐catenin signaling pathway but induced apoptosis via the noncanonical JNK pathway in renal cancer cells. Expression of p21, MDM‐2, and Puma genes were increased after transfecting RCC cell lines with a Dkk‐3 expression plasmid. Overexpression of Dkk‐3 induced G0/G1 arrest together with an increase in p21 expression. Growth of stable Dkk‐3 transfected cells in nude mice was decreased compared to controls. Our data show for the first time that mRNA expression of Dkk‐3 is regulated by histone modification and that Dkk‐3 inhibits renal cancer growth through modulation of cell cycle and apoptotic pathways. © 2011 Wiley‐Liss, Inc.
p38 MAP kinase plays a functional role in UVB‐Induced mouse skin carcinogenesis
Authors: Dickinson Sally E. , Olson Erik R. , Zhang Jack , Cooper Simon J. , Melton Tania , Criswell P. Jane , Casanova Ana , Dong Zigang , Hu Chengcheng , Saboda Kathylynn , Jacobs Elizabeth T. , Alberts David S. , Bowden G. Tim
Published: January 2011

UVB irradiation of epidermal keratinocytes results in the activation of the p38 mitogen‐activated protein kinase (MAPK) pathway and subsequently activator protein‐1 (AP‐1) transcription factor activation and cyclooxygenase‐2 (COX‐2) expression. AP‐1 and COX‐2 have been shown to play functional roles in UVB‐induced mouse skin carcinogenesis. In this study, the experimental approach was to express a dominant negative p38α MAPK (p38DN) in the epidermis of SKH‐1 hairless mice and assess UVB‐induced AP‐1 activation, COX‐2 expression, and the skin carcinogenesis response in these mice compared to wild‐type littermates. We observed a significant inhibition of UVB‐induced AP‐1 activation and COX‐2 expression in p38DN transgenic mice, leading to a significant reduction of UVB‐induced tumor number and growth compared to wild‐type littermates in a chronic UVB skin carcinogenesis model. A potential mechanism for this reduction in tumor number and growth rate is an inhibition of chronic epidermal proliferation, observed as reduced Ki‐67 staining in p38DN mice compared to wild‐type. Although we detected no difference in chronic apoptotic rates between transgenic and nontransgenic mice, analysis of acutely irradiated mice demonstrated that expression of the p38DN transgene significantly inhibited UVB‐induced apoptosis of keratinocytes. These results counter the concerns that inhibition of p38 MAPK in a chronic situation could compromise the ability of the skin to eliminate potentially tumorigenic cells. Our data indicate that p38 MAPK is a good target for pharmacological intervention for UV‐induced skin cancer in patients with sun damaged skin, and suggest that inhibition of p38 signaling reduces skin carcinogenesis by inhibiting COX‐2 expression and proliferation of UVB‐irradiated cells. © 2011 Wiley‐Liss, Inc.
NMR property calculations and experimental study of the 1,6‐epoxycarvone and α‐epoxypinene: a comparison of models
Authors: Queiroz Luiz H. K. , Lacerda Valdemar , dos Santos Reginaldo B. , Greco Sandro J. , Cunha Neto Álvaro , de Castro Eustaquio V. R.
Published: January 2011

This work aims at using theoretical calculations of shielding tensors (σ) through different methods [gauge‐independent atomic orbital (GIAO), continuous set of gauge transformations (CSGT) and individual gauges for atoms in molecules (IGAIM)] and spin‐spin coupling constants J using GIAO method to compare these methods and to corroborate the data obtained with the assignment of all of 1H and 13C NMR signals and the relative stereochemistry of the 1,6‐epoxycarvone and the α‐epoxypinene. All the 1H and 13C NMR signals were assigned unequivocally. The stereochemistry for the epoxides is trans and the B3LYP theory level with CSGT and IGAIM methods is the best choice to evaluate theoretical chemical shifts for compounds studied. Copyright © 2011 John Wiley & Sons, Ltd.
Comprehensive Investigation of Catalyst Structure and Polymerization Conditions for Chain Branching in Ethylene Polymerization with Phillips‐Type Catalysts
Authors: Tonosaki Kiwamu , Taniike Toshiaki , Terano Minoru
Published: January 2011

Control factors of branching in ethylene polymerization on CrOx/SiO2 catalysts were comprehensively investigated by varying catalyst structure and polymerization conditions. Variation of the polymerization conditions such as polymerization time, catalyst concentration, polymerization temperature, and alkylaluminum concentration indicated that the branch frequencies in produced polyethylene were highly relevant to the polymerization yield, plausibly through concentration of in‐situ‐produced α‐olefins. A method to fairly compare the branching abilities of different catalysts was proposed. The application of the method to model catalysts with controlled chromium nuclearity proved an important role of dinuclear species in methyl branching through olefin metathesis.

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Macro electromyography and motor unit number index in the tibialis anterior muscle: Differences and similarities in characterizing motor unit properties in prior polio
Authors: Sandberg Arne , Nandedkar Sanjeev D. , Stålberg Erik
Published: January 2011

Our objective was to establish the usefulness of the noninvasive method of the motor unit number index (MUNIX) in a large muscle and to study how macro electromyography (EMG) and MUNIX complement each other in describing the motor units (MUs) in prior polio. MUNIX and macro EMG were performed in 48 tibialis anterior muscles in 33 prior polio patients. In addition, the reproducibility of MUNIX was investigated. It is shown that MUNIX can be used to characterize MUs with high reproducibility, even in a large muscle. As judged by MUNIX values, the patients had a 25% reduction of motor neurons, whereas the macro EMG indicated a loss of 60% of the neurons. Macro EMG showed more pronounced changes compared with control material than the MUNIX. One of the reasons for this finding may be the difference in MU populations studied with the two methods. Muscle Nerve, 2011
How well informed are women who undergo urodynamic testing?
Authors: Neustaedter E. Grace , Milne Jill , Shorten Kathleen , Weckman Betty , Tse Angela , Tange Selphee
Published: January 2011

Aims

Urodynamic studies (UDS) are complex, invasive and may be emotionally and physically distressing. Inadequate information may heighten distress. Prior to UDS, our patients receive written and verbal information, yet concerns remains that some women may not be adequately informed. This study examined how informed women believe they are to undergo UDS in our clinic.

Methods

This was a before–after questionnaire‐based study. Data were collected from a convenience sample of 200 women prior to UD testing, and within 3 days of completion. Participants rated their level of agreement/disagreement with the following statements: I understand why I am having the test; I have been given enough information about the test; I understand what the test will involve. Women also reported their perceived levels of distress (anxiety, embarrassment, and discomfort).

Results

One hundred fifty‐one women returned both pre‐ and post‐UD questionnaires. Most (88.9%) had read the information sheet and agreed that they understood the indications for the testing (78.1%). Fewer agreed that they understood what the tests would involve (68.2%), or that they had been given enough information about the test (64.9%). The overall distress score (anxiety, embarrassment, and discomfort) was 6 (IQR 5–7; possible range 3–9).

Conclusions

Urodynamic testing remains an invasive yet prevalent form of urogynecological assessment. One‐third of our patients may not understand what UD testing involves and may not feel adequately informed about the tests. Additional research to explore informational needs is important. 30:572–577, 2011. © 2011 Wiley‐Liss, Inc.
Access link bandwidth externalities and endogenous Internet growth: a long‐run economic approach
Authors: Androutsos Athanassios
Published: January 2011

The evolution of end‐users' access link bandwidth over time arrives exogenously in network economics and it is typically attributed to technological advances in the area of networking. In this paper, we explore the broad issues associated with developing an economic model of access link bandwidth growth. In the proposed model bandwidth of the access link grows endogenously based on the increasing performance and quality of service requirements of the emerging Internet applications that have resulted in massive increases in demand for access capacity rates. A significant consideration of this model is that bandwidth exhibits substantial externalities or spillovers since decisions on bandwidth levels made by a single user affect all other user levels of performance. The main conclusions are that access link bandwidth externalities determine the rate of access bandwidth and Internet growth, that integration of separate networks into a universal multimedia networking technology managed by a single administration scheme and the integration of bandwidth provisioning into aggregate markets will increase the rate of growth, and that having a large user population is not sufficient to generate growth. Copyright © 2011 John Wiley & Sons, Ltd.
Mitigating unfairness in locality‐aware peer‐to‐peer networks
Authors: Lehrieder Frank , Oechsner Simon , Hoßfeld Tobias , Staehle Dirk , Despotovic Zoran , Kellerer Wolfgang , Michel Maximilian
Published: January 2011

Locality awareness is considered as a promising approach to increase the efficiency of content distribution by peer‐to‐peer (P2P) networks, e.g., BitTorrent. It is intended to reduce the inter‐domain traffic, which is costly for Internet service providers (ISPs), and to simultaneously increase the performance from the viewpoint of P2P users, i.e., to shorten download times. This win–win situation should be achieved by a preferred exchange of information between peers which are located close to each other in the underlying network topology. A set of studies shows that these approaches can lead to a win–win situation under certain conditions, and to a win–no lose situation in most cases. However, the scenarios used mostly assume homogeneous peer distributions. This is not the case in practice according to recent measurement studies. Therefore, we extend previous work in this paper by studying scenarios with real‐life, skewed peer distributions. We show that even a win–no lose situation is difficult to achieve under those conditions and that the actual impact for a specific peer heavily depends on the used locality‐aware peer selection and the specific scenario. This contradicts the principle of economic traffic management (ETM), which aims for a solution where all involved players benefit and consequently have an incentive to adopt locality awareness. Therefore, we propose and evaluate refinements of current proposals, allowing all users of P2P networks to be sure that their application performance is not reduced. This mitigates the unfairness introduced by current proposals which is a key requirement for a broad acceptance of the concept of locality awareness in the user community of P2P networks. Copyright © 2011 John Wiley & Sons, Ltd.
Drug utilization and polypharmacy in an Italian elderly population: the EPIFARM‐elderly project
Authors: Nobili Alessandro , Franchi Carlotta , Pasina Luca , Tettamanti Mauro , Baviera Marta , Monesi Lara , Roncaglioni Carla , Riva Emma , Lucca Ugo , Bortolotti Angela , Fortino Ida , Merlino Luca
Published: January 2011

Objective

To investigate the prescribing patterns and the prevalence of polypharmacy in community‐dwelling elderly people, and to analyze the association of chronic medications and number of drug prescriptions with age and sex.

Methods

All prescriptions for people aged 65 years or older reimbursed by the Italian National Health Service (NHS) and dispensed by retail pharmacies of the 15 local health units (LHU) in the Lombardy Region during 2005 were analyzed. Logistic regression analysis was used to assess the association between drug prescription (overall, chronic drugs, and polypharmacy) and age, sex, and LHU of residence.

Results

Eighty‐eight percent of the 1 767 239 analyzed elderly received at least one drug prescription. The overall prescription rate was slightly higher for women than men (odds ratio [OR] 1.20; 95%CI 1.19–1.21). Seventy‐six percent of the elderly received at least one chronic drug, 46% were exposed to polypharmacy, and 20% to chronic polypharmacy. At multivariate analysis, age and LHU residence of the elderly were the main determinants of drug exposure. A significant correlation was found between the overall prescription prevalence rate and exposure to chronic drugs and to chronic polypharmacy (rs = 0.79, p < 0.0005 and rs = 0.84, p < 0.0001, respectively).

Conclusions

Our findings indicate that age and LHU residence of the elderly are the main determinants of drug prescribing, and there is evidence of a significant correlation between the overall prescription prevalence rate and exposure to chronic drugs and to chronic polypharmacy. Copyright © 2011 John Wiley & Sons, Ltd.
Environment‐friendly silicone sealants by self‐catalytic cross‐linking reaction of α‐aminomethyl triethoxysilanes
Authors: Yin Yigao , Zhang Yi , Chen Xiaoyan , Liu Siwei , Jiang Xing , Chi Zhenguo , Xu Jiarui
Published: January 2011

On the basis of the self‐catalytic characteristic of α‐aminomethyl triethoxysilanes, (diethyl) aminomethyl triethoxysilane, cyclohexylaminomethyl triethoxysilane, and anilinomethyl triethoxysilane were used as self‐catalytic cross‐linkers to prepare a series of environmental friendly, nano‐CaCO3 reinforced silicone sealants based on poly(dimethylsiloxane) (PDMS). The tensile properties, hardness, adhesive properties, hot‐air aging resistance, and oil‐resistance properties of these materials were studied by universal electronic tensile machine, scanning electron microscope, and atomic force microscopy, etc. Results show that the comprehensive properties of the self‐catalytic cross‐linking PDMS sealants are much better than that of the traditional ones. The chemical structure and reactivity of the α‐aminomethyl triethoxysilanes have a great effect on the properties of PDMS sealants. The tensile strength of the reinforced sealants with 100 phr (100 parts per hundreds of PDMS) nano‐CaCO3 is about 4.4 times than that of the unreinforced ones, and the elongation at break is about three times. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Exploring the proteome of an echinoderm nervous system: 2‐DE of the sea star radial nerve cord and the synaptosomal membranes subproteome
Authors: Franco Catarina Ferraz , Santos Romana , Coelho Ana Varela
Published: January 2011

We describe the first proteomic characterization of the radial nerve cord (RNC) of an echinoderm, the sea star Marthasterias glacialis. The combination of 2‐DE with MS (MALDI‐TOF/TOF) resulted in the identification of 286 proteins in the RNC. Additionally, 158 proteins were identified in the synaptosomal membranes enriched fraction after 1‐DE separation. The 2‐DE RNC reference map is available via the WORLD‐2DPAGE Portal (http://www.expasy.ch/world‐2dpage/) along with the associated protein identification data which are also available in the PRIDE database. The identified proteins constitute the first high‐throughput evidence that seems to indicate that echinoderms nervous transmission relies primarily on chemical synapses which is similar to the synaptic activity in adult mammal's spinal cord. Furthermore, several homologous proteins known to participate in the regeneration events of other organisms were also identified, and thus can be used as targets for future studies aiming to understand the poorly uncharacterized regeneration capability of echinoderms. This “echinoderm missing link” is also a contribution to unravel the mystery of deuterostomian CNS evolution.
Mechanical properties of polymer‐blend nanocomposites with organoclays: Polystyrene/ABS and high impact polystyrene/ABS
Authors: Chen Biqiong , Evans Julian R. G.
Published: January 2011

Thirty‐three polystyrene (PS)/acrylonitrile‐butadiene‐styrene (ABS) and high impact PS/ABS polymer blends with organoclay and copolymer additives were prepared by melt processing using different mixing sequences in order to test the putative capability of clay to perform a compatibilizing role in polymer blends. In general, the addition of clay increased the tensile modulus and had little effect on tensile strength. For the blends studied in this work, the addition of organoclays caused a catastrophic reduction in impact strength, a critical property for commercial viability. The polymer‐blend nanocomposites adopted a structure similar to that for ABS/clay nanocomposites as determined by X‐ray diffraction and transmission electron microscopy. It is suggested that clay reinforcement inhibits energy absorption by craze formation and shear yielding at high strain rates. Simultaneous mixing of the three components provided nanocomposites with superior elongation and energy to failure compared to sequential mixing. The clay pre‐treated with a benzyl‐containing surfactant gave the best overall properties among the various organoclays tested and of the two clay contents studied 4 wt % was preferred over 8 wt % addition. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Peak window of suicides occurs within the first month of diagnosis: implications for clinical oncology
Authors: Johnson Timothy V. , Garlow Steven J. , Brawley Otis W. , Master Viraj A.
Published: January 2011

Objective: A diagnosis of cancer can provoke painful emotional reactions and possibly suicidal thoughts in a patient. Consequently, cancer patients carry a twofold increased lifetime risk of suicide. This risk is much higher within 1 year of diagnosis. However, it remains largely unknown whether suicide frequency remains constant within the first year. Therefore, we sought to characterize the distribution of suicides in order to potentially identify a clinically important window of peak suicide risk.

Methods: We queried the Surveillance, Epidemiology, and End Results (SEER) database for cancer patients 20 + years old with diagnosed with a single malignancy from 1973 to 2005 and known cause of death, including whether a patient committed suicide. Initial frequency analysis was performed to identify the period of maximum suicide risk. One‐way ANOVA was performed to assess the relationship between year of diagnosis and suicide completions within 1 month of diagnosis.

Results: The cohort consisted of 3 678 868 patients. Of the total cohort, 0.2% (5875 patients) committed suicide, 36% (2111 patients) within 1 year of diagnosis. One in three (701 of the patients) who committed suicide in the first year did so within 1 month of diagnosis. No change in this distribution occurred over time.

Conclusions: Cancer patients carry an increased risk of suicide. However, this risk peaks with the month following diagnosis. Clinicians should be aware of this increased risk and include assessments of mood state and suicidality at the time of initial diagnosis of the malignancy and be prepared to provide referral to mental health treatment providers. Copyright © 2011 John Wiley & Sons, Ltd.
Efficacy of selected pesticides against synanthropic mites under laboratory assay
Authors: Stará Jitka , Stejskal Václav , Nesvorná Marta , Plachý Jan , Hubert Jan
Published: January 2011

BACKGROUND: The efficacies of organophosphate pesticides, single‐compound versus multicompound pyrethroid formulations and relatively novel unclassified insecticides/acaricides were compared to find the lowest dosage and highest efficacy for the control of Dermatophagoides farina (Hughes), D. pteronyssinus (Trouessart) and Tyrophagus putrescentiae (Schrank). Formulated active ingredients (AIs) were diluted in water and applied onto filter paper in experimental chambers with ten unsexed adult mites in six replicates. Mite mortality was checked after 24 h. The security index (SI) was calculated for all of the AIs by dividing the recommended rate by the LD90 determined for each species.

RESULTS: The tested organophosphates had high LD90 and low SI values. The single‐compound pyrethroids were ineffective (deltamethrin and beta‐cyfluthrin) or had high LD90 and low SI values (cyphenothrin, permethrin, pyrethrum and bifenthrin). The multicompound miticides had low LD90 and high SI values which increased from deltamethrin/S‐bioallethrin to permethrin/S‐bioallethrin/piperonyl butoxide to permethrin/pyriproxyfen/benzyl benzoate. Abamectin, pyridaben, propargite and flufenoxuron were highly active against Dermatophagoides spp. Neem (Acarosan duo) was highly active against all mite species tested.

CONCLUSION: The available formulations of multicompound pyrethroids (permethrin/S‐bioallethrin/piperonyl butoxide, permethrin/pyriproxyfen/benzyl benzoate), benzyl benzoate, neem and some field acaricides are effective in suppression of synanthropic mites in laboratory assays. Their LD90 are lower than those of traditionally used organophosphates or single‐compound pyrethroid formulations. Copyright © 2011 Society of Chemical Industry
Auger recombination in Si1‐xGex/Si quantum wells under high‐density photoexcitation
Authors: Tayagaki Takeshi , Fukatsu Susumu , Kanemitsu Yoshihiko
Published: January 2011

We studied the Auger recombination in Si1‐xGex /Si quantum wells using near‐infrared photoluminescence (PL) spectroscopy. We found that the PL intensity under high‐density excitation depends strongly on the width of the single quantum wells and that the Auger recombination is more pronounced for wide wells. This indicates that the Auger recombination rate depends on the spatial profile of the hole wave function in the Si1‐xGex well layer. We discuss the method to control the nonradiative Auger recombination rate in coupled double quantum wells (CDQWs) by manipulating the wave functions; the rate is reduced by tuning the barrier width. In CDQWs voltage‐biased on the surface, the PL intensity decrease with surface voltage, but the electric field dependence of the PL intensity is complicated under low‐density‐excitation condition. This unique electric‐field dependence of the PL intensity is sensitive to the excitation intensity and the sample temperature. We tentatively attribute these PL behaviors to the appearance of the impact ionization under the low excitation intensity and high‐surface‐bias voltage conditions. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Black luminescent silicon
Authors: Pezoldt Jörg , Kups Thomas , Stubenrauch Mike , Fischer Michael
Published: January 2011

Black silicon is a fascinating multipurpose modification of bulk silicon which can be fabricated in a selforganized structure formation process during dry etching of bare silicon wafer leading to the formation of a high density of silicon needles. The smallest dimension of the tips approaches values between 1 and 2 nm. The silicon nanostructure exhibits an extremely low diffuse reflectivity. The nanosized tips and their coating with fluorine doped nonstoichiometric silicon dioxide are responsible for cathodoluminescence in the blue‐green and red regions of the visible spectra (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the role of heterolayer relaxation in luminescence response of Si/SiGe:Er structures
Authors: Krasilnikova Ludmila , Stepikhova Margarita , Drozdov Yurij , Chalkov Vadim , Shengurov Vladimir , Krasilnik Zakharii
Published: January 2011

In this contribution we discuss the luminescence properties of Si/Si1‐xGex:Er/Si structures being of interest for a laser realization. The influence of the strain relaxation processes that take place in such kind of structures on their photoluminescence response at 1.54 µm has been analyzed. The studies were performed for Si/Si1‐xGex:Er/Si structures with the different thickness of Si1‐xGex:Er layers, and consequently the degree of strain relaxation. It is shown that the structural defects arising in Si/Si1‐xGex:Er/Si structures due to the relaxation play only negligible role in their photoluminescence response. The contribution of the structural defects in the photoluminescence response at 1.54 µm became apparent only in thin partially relaxed Si/Si1‐xGex:Er/Si structures, the photoluminescence spectra of which are represented by the broad “defect related” lines. Intense photoluminescence related with the optically active Er centers of different types was observed for the strained and completely relaxed Si/Si1‐xGex:Er/Si structures containing thick (d > 1 µm) Si1‐xGex:Er layers. The external quantum efficiency of these structures reaches the value of 6.3×10‐5 at T =77 K. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ultrafast photoluminescence dynamics of blue‐emitting silicon nanostructures
Authors: Židek K. , Trojánek F. , Malý P. , Pelant I. , Gilliot P. , Hönerlage B.
Published: January 2011

We report on ultrafast photoluminescence (PL) spectroscopy of blue and red‐emitting silicon nanostructures. We prepared samples of porous Si with different dominating PL bands in time‐integrated PL spectrum. These samples show also striking differences in ultrafast PL dynamics. For the red‐emitting samples we observe rapid PL onset followed by a two‐exponential decay, which is spectrally dependent. For the blue‐emitting porous Si the PL builds up several picoseconds and decays mono‐exponentially with spectrally independent PL rise and decay times.

Our results indicate that a dominant part of the blue and red emission comes from two distinct species with different energy states structures. This is furthermore supported by two‐photon absorption induced PL mea‐surements. The two‐photon and one‐photon absorption induced PL spectra, which are identical for the red‐emitting samples, differ substantially for the blue‐emitting ones. However, polarization properties of PL suggest that the blue PL band originates from several overlapping PL bands with sample‐dependent importance. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phonon‐assisted exciton spin relaxation in (In,Ga)As/GaAs quantum dots
Authors: Kurtze H. , Yakovlev D. R. , Reuter D. , Wieck A. D. , Bayer M.
Published: January 2011

In this work, we study the temperature‐dependent spin relaxation of exciton‐bound carriers in (In,Ga)As/GaAs quantum dots. The exciton population mapped by a time‐resolved differential transmission signal reveals a decay on two different time scales, reflecting the fractions of optically active and inactive excitons. The underlying exciton states are split from each other by the exchange interaction. The phonon‐assisted spin‐orbit interaction induces spin flips of an exciton‐bound electron or hole which convert the exciton populations into each other. The temperature‐dependent relaxation rate follows a thermal phonon distribution. Deviations indicate that two‐phonon processes involving higher orbitals may contribute significantly to the total relaxation process. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quasi‐two‐dimensional electron–hole liquid and biexcitons in SiGe layers of Si/SiGe/Si heterostructures
Authors: Shepel Denis , Burbaev Timur , Sibeldin Nikolai , Skorikov Mikhail
Published: January 2011

The electron–hole liquid (EHL) in quantum‐confinement SiGe layers of Si/Si1‐xGex /Si heterostructures is discovered and its properties are studied by photoluminescence spectroscopy in the near‐infrared and visible spectral ranges. It is established that the EHL is composed by quasi‐two‐dimensional holes in the quantum well formed by the SiGe layer and quasi‐three‐dimensional electrons, which occupy a wider region of space centered on this layer. Conditions on the band parameters of a type‐II heterostructure under which the formation of the EHL and biexcitons in such a structure is possible are determined. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phonon‐assisted decoherence and tunneling in quantum dot molecules
Authors: Grodecka‐Grad Anna , Förstner Jens
Published: January 2011

We study the influence of the phonon environment on the electron dynamics in a doped quantum dot molecule. A non‐perturbative quantum kinetic theory based on correlation expansion is used in order to describe both diagonal and off‐diagonal electron‐phonon couplings representing real and virtual processes with relevant acoustic phonons.

We show that the relaxation is dominated by phonon‐assisted electron tunneling between constituent quantum dots and occurs on a picosecond time scale. The dependence of the time evolution of the quantum dot occupation probabilities on the energy mismatch between the quantum dots is studied in detail. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phonon sidebands in the semiconductor microcavity luminescence
Authors: Böttge Christoph N. , Feldtmann Thomas , Kira Mackillo , Koch Stephan W.
Published: January 2011

A microscopic theory is developed to study the optical properties of semiconductor systems with strong phonon coupling inside a cavity. The semiconductor luminescence equations are expanded to include the phonon‐assisted contributions.

Numerical investigations predict a considerably enhanced luminescence when the cavity resonance is shifted to coincide with the phonon sideband resonance. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Twentieth Century Reanalysis Project
Authors: Compo G. P. , Whitaker J. S. , Sardeshmukh P. D. , Matsui N. , Allan R. J. , Yin X. , Gleason B. E. , Vose R. S. , Rutledge G. , Bessemoulin P. , Brönnimann S. , Brunet M. , Crouthamel R. I. , Grant A. N. , Groisman P. Y. , Jones P. D. , Kruk M. C. , Kruger A. C. , Marshall G. J. , Maugeri M. , Mok H. Y. , Nordli Ø. , Ross T. F. , Trigo R. M. , Wang X. L. , Woodruff S. D. , Worley S. J.
Published: January 2011

The Twentieth Century Reanalysis (20CR) project is an international effort to produce a comprehensive global atmospheric circulation dataset spanning the twentieth century, assimilating only surface pressure reports and using observed monthly sea‐surface temperature and sea‐ice distributions as boundary conditions. It is chiefly motivated by a need to provide an observational dataset with quantified uncertainties for validations of climate model simulations of the twentieth century on all time‐scales, with emphasis on the statistics of daily weather. It uses an Ensemble Kalman Filter data assimilation method with background ‘first guess’ fields supplied by an ensemble of forecasts from a global numerical weather prediction model. This directly yields a global analysis every 6 hours as the most likely state of the atmosphere, and also an uncertainty estimate of that analysis.

The 20CR dataset provides the first estimates of global tropospheric variability, and of the dataset's time‐varying quality, from 1871 to the present at 6‐hourly temporal and 2° spatial resolutions. Intercomparisons with independent radiosonde data indicate that the reanalyses are generally of high quality. The quality in the extratropical Northern Hemisphere throughout the century is similar to that of current three‐day operational NWP forecasts. Intercomparisons over the second half‐century of these surface‐based reanalyses with other reanalyses that also make use of upper‐air and satellite data are equally encouraging.

It is anticipated that the 20CR dataset will be a valuable resource to the climate research community for both model validations and diagnostic studies. Some surprising results are already evident. For instance, the long‐term trends of indices representing the North Atlantic Oscillation, the tropical Pacific Walker Circulation, and the Pacific–North American pattern are weak or non‐existent over the full period of record. The long‐term trends of zonally averaged precipitation minus evaporation also differ in character from those in climate model simulations of the twentieth century. Copyright © 2011 Royal Meteorological Society and Crown Copyright.
An approach to optimization of fault tolerant architectures using HiP‐HOPS
Authors: Adachi Masakazu , Papadopoulos Yiannis , Sharvia Septavera , Parker David , Tohdo Tetsuya
Published: January 2011

New processes for the design of dependable systems must address both cost and dependability concerns. They should also maximize the potential for automation to address the problem of increasing technological complexity and the potentially immense design spaces that need to be explored. In this paper we show a design process that integrates system modelling, automated dependability analysis and evolutionary optimization techniques to achieve the optimization of designs with respect to dependability and cost from the early stages. Computerized support is provided for difficult aspects of fault tolerant design, such as decision making on the type and location of fault detection and fault tolerant strategies. The process is supported by HiP‐HOPS, a scalable automated dependability analysis and optimization tool. The process was applied to a Pre‐collision system for vehicles at an early stage of its design. The study shows that HiP‐HOPS can overcome the limitations of earlier work based on Reliability Block Diagrams by enabling dependability analysis and optimization of architectures that may have a network topology and exhibit multiple failure modes. Copyright © 2011 John Wiley & Sons, Ltd.
Strain Hardening Behavior of High Performance FBDP, TRIP and TWIP Steels
Authors: Cai Ming‐hui , Ding Hua , Tang Zheng‐you , Lee Hua‐ying , Lee Young‐kook
Published: January 2011

Based on n‐value differential equation and microstructural observation, strain hardening behaviors of FBDP, TRIP, and TWIP steels during uniaxial tension were investigated. TRIP steel exhibits both superior strength and ductility than FBDP steel, and TWIP steel displays much higher total and uniform elongations in comparison to FBDP and TRIP steels. The instantaneous n values of FBDP and TRIP steels increase at small strains, reach a maximum value, smoothly decrease at higher strains, and then rapidly drop up to the specimen rupture. The strain hardening of TRIP steel persists at higher strains where that of FBDP steel begins to diminish. TWIP steel exhibits gradually increased instantaneous n values over the whole uniform plastic deformation, implying that TWIP steel shows a much larger strain hardening capability than FBDP and TRIP steels.
The effects of nicotine and cigarette smoke on the monoamine transporters
Authors: Danielson Kirsty , Truman Penelope , Kivell Bronwyn M
Published: January 2011

Cigarette smoking is the leading cause of preventable illness worldwide; however, smoking addiction remains poorly understood and cessation therapies based on nicotine replacement have limited success. The monoamine transporters are the primary mechanism for regulating the levels of dopamine, serotonin and norepinephrine in the synapse, and have been implicated in addiction and associated behaviors. Furthermore, the non‐nicotinic smoking cessation therapy bupropion acts at least in part by blocking the dopamine and norepinephrine transporters. Despite this, little work has been conducted into the effects of nicotine and cigarette smoke on the monoamine transporters. This review will outline research that has been conducted to date on cigarette smoke, nicotine and the monoamine transporters. This will include monoamine transporter regulation by nicotine and cigarette smoke, genetic associations of the transporters with smoking behavior, and the potential for monoamine transporters to be targets in the development of smoking cessation pharmacotherapies. Synapse , 2011. © 2011 Wiley‐Liss, Inc.
Über Alkalimetallmanganchalkogenide A2MnX2 mit A K, Rb oder Cs und X S, Se oder Te
Authors: Bronger W. , Balk‐Hardtdegen H. , Schmitz D.
Published: January 2011

Inhaltsübersicht. Die Verbindungen K2MnS2, Rb2MnS2, Cs2MnS2, K2MnSe2, Rb2MnSe2, Cs2MnSe2, K2MnTe2, Rb2MnTe2 und Cs2MnTe2 wurden durch Umsetzungen von Alkalimetall‐carbonaten mit Mangan bzw. Mangantellurid in einem mit Chalkogen beladenen Wasserstoffstrom erhalten.

Kristallstrukturuntersuchungen an Einkristallen ergaben, daß alle neun Verbindungen isotyp kristallisieren (K2ZnO2‐Typ, Raumgruppe Ibam).

Untersuchungen zum magnetischen Verhalten zeigen antiferromagnetische Kopplungen der Manganionen in den [MnX4/22–]‐Ketten,

On Alkali Metal Manganese Chalcogenides A2MnX2 with A K, Rb, or Cs and X S, Se, or Te

The compounds K2MnS2, Rb2MnS2, Cs2MnS2, K2MnSe2, Rb2MnSe2, Cs2MnSe2, K2MnTe2, Rb2MnTe2, and Cs2MnTe2 were synthesized by the reaction of alkali metal carbonates with Mn or MnTe in a stream of hydrogen charged with chalcogen.

Structural investigations on single crystals show that all nine compounds crystallize in isotypic atomic arrangements (K2ZnO2 type, space group Ibam).

The magnetic behaviour indicates antiferromagnetic interactions of the manganese ions within the [MnX1/22–] chains.
Influence of Intraoperative Neuromonitoring on Surgeons’ Technique During Thyroidectomy
Authors: Duclos Antoine , Lifante Jean‐Christophe , Ducarroz Simon , Soardo Pietro , Colin Cyrille , Peix Jean‐Louis
Published: January 2011

Background

When assessing the value of intraoperative nerve monitoring (IONM) during routine thyroidectomy, it is necessary to consider its influence on the surgeon’s dissection technique. We investigated the effect of IONM on individual surgeon performance by determining the learning curve associated with this tool.

Methods

A one‐year prospective study was conducted between May 2008 and April 2009 within a team of three experienced endocrine surgeons. The measure of surgical performance was based on the detection of immediate postoperative recurrent laryngeal nerve palsy by laryngoscopy. Individual learning curves associated with IONM acquisition were drawn with the cumulative sum (CUSUM) chart. Each surgeon was questioned about possible changes he had experienced in his own surgical technique after the introduction of IONM.

Results

A total of 475 consecutive patients who underwent thyroid surgery with IONM were included. The pattern of learning curves varied among surgeons and ranged from 35 to 304 procedures required for complete IONM acquisition. The surgeon with the longest learning curve also described a drastic modification of his technique related to nerve dissection.

Conclusions

Intraoperative nerve monitoring can induce changes in surgical practice. The different learning curve patterns among surgeons may reflect the variable degree to which surgeons will modify their own dissection technique. Such an effect on learning must be considered when assessing the impact of using IONM on patient safety.
Validation of a Self‐Concept Scale for Lynch Syndrome in Different Nationalities
Authors: Petersen Helle Vendel , Domanska Katarina , Bendahl Pär‐Ola , Wong Jiahui , Carlsson Christina , Bernstein Inge , Esplen Mary Jane , Nilbert Mef
Published: January 2011

Learning about hereditary cancer may influence an individual's self‐concept, which otherwise represents a complex but stable cognitive structure. Recently, a 20‐statement self‐concept scale, with subscales related to stigma‐vulnerability and bowel symptom‐related anxiety, was developed for Lynch syndrome. We compared the performance of this scale in 591 mutation carriers from Denmark, Sweden and Canada. Principal component analysis identified two sets of linked statements—the first related to feeling different, isolated and labeled, and the second to concern and worry about bowel changes. The scale performed consistently in the three countries. Minor differences were identified, with guilt about passing on a defective gene and feelings of losing one's privacy being more pronounced among Canadians, whereas Danes more often expressed worries about cancer. Validation of the Lynch syndrome self‐concept scale supports its basic structure, identifies dependence between the statements in the subscales and demonstrates its applicability in different Western populations.
The transposon-driven evolutionary origin and basis of histone deacetylase functions and limitations in disease prevention
Authors: Peek Gregory W. , Tollefsbol Trygve O.
Published: January 2011

Histone deacetylases (HDACs) are homologous to prokaryotic enzymes that removed acetyl groups from non-histone proteins before the evolution of eukaryotic histones. Enzymes inherited from prokaryotes or from a common ancestor were adapted for histone deacetylation, while useful deacetylation of non-histone proteins was selectively retained. Histone deacetylation served to prevent transcriptions with pathological consequences, including the expression of viral DNA and the deletion or dysregulation of vital genes by random transposon insertions. Viruses are believed to have evolved from transposons, with transposons providing the earliest impetus of HDAC evolution. Because of the wide range of genes potentially affected by transposon insertions, the range of diseases that can be prevented by HDACs is vast and inclusive. Repressive chromatin modifications that may prevent transcription also include methylation of selective lysine residues of histones H3 and H4 and the methylation of selective DNA cytosines following specific histone lysine methylation. Methylation and acetylation of individual histone residues are mutually exclusive. While transposons were sources of disease to be prevented by HDAC evolution, they were also the source of numerous and valuable coding and regulatory sequences recruited by “molecular domestication.” Those sequences contribute to evolved complex transcription regulation in which components with contradictory effects, such as HDACs and HATs, may be coordinated and complementary. Within complex transcription regulation, however, HDACs remain ineffective as defense against some critical infectious and non-infectious diseases because evolutionary compromises have rendered their activity transient.