bluuebunny/crossref_metadata_2025 huggingface dataset:
On the computation of the class number of an algebraic number field
Authors: Buchmann Johannes , Williams H. C.
Published: June 2010

It is shown how the analytic class number formula can be used to produce an algorithm which efficiently computes the class number h of an algebraic number field F. The method assumes the truth of the Generalized Riemann Hypothesis in order to estimate the residue of the Dedekind zeta function of F at

s
=
1

s = 1

sufficiently well that h can be determined unambiguously. Given the regulator R of F and a known divisor

h
∗

{h^ \ast }

of h, it is shown that this technique will produce the value of h in

O
(

|

d
F

|

1
+
ε

/

(

h
∗

R

)
2

)

O(|{d_F}{|^{1 + \varepsilon }}/{({h^ \ast }R)^2})

elementary operations, where

d
F

{d_F}

is the discriminant of F. Thus, if

h
>

|

d
F

|

1

/

8

h > |{d_F}{|^{1/8}}

, then the complexity of computing h (with

h
∗

=
1

{h^ \ast } = 1

) is

O
(

|

d
F

|

1

/

4
+
ε

)

O(|{d_F}{|^{1/4 + \varepsilon }})

.
Long chains of nearly doubled primes
Authors: Löh Günter
Published: June 2010

A chain of nearly doubled primes is an ordered set

{

a
1

,

a
2

,
…
,

a
λ

}

\{ {a_1},{a_2}, \ldots ,{a_\lambda }\}

of prime numbers, interlinked by

a
k

=
2

a

k
−
1

±
1

{a_k} = 2{a_{k - 1}} \pm 1

. A search for long chains of this kind has been performed in the range

a
1

>

2

50

{a_1} > {2^{50}}

. Chains of length up to 13 have been found. Shorter chains have been counted in some restricted ranges. Some of these counts are compared with the frequencies predicted by a quantitative version of the prime k-tuples conjecture.
Effective bounds for the maximal order of an element in the symmetric group
Authors: Massias Jean-Pierre , Nicolas Jean-Louis , Robin Guy
Published: June 2010

Let

σ
n

\sigma _n

be the symmetric group of n elements and
\[

g
(
n
)
=

max

σ
∈

σ
n

(

order of 

σ

)
.

g(n) = \max _{\sigma \in \sigma _n}(\text {order of $\sigma $} ).

\]
We give here some effective bounds for

g
(
n
)

g(n)

and

P
(
g
(
n
)
)

P(g(n))

(greatest prime divisor of

g
(
n
)

g(n)

). Theoretical proofs are in "Evaluation asymptotique de l’ordre maximum d’un élément du groupe symétrique" (Acta Arith., v. 50, 1988, pp. 221-242). The tools used here are techniques of superior highly composite numbers of Ramanujan and bounds of Rosser and Schoenfeld on the Chebyshev function

θ
(
x
)

\theta (x)

.
Approximations for weakly nonlinear evolution equations
Authors: Miklavčič Milan
Published: June 2010

Convergence of approximations for a large class of weakly nonlinear parabolic and hyperbolic equations is proven. The main emphasis is on proving convergence of finite element and spectral Galerkin approximations of solutions to the weakly nonlinear wave equation
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="u left-parenthesis t right-parenthesis plus upper A u left-parenthesis t right-parenthesis equals upper F left-parenthesis t comma u left-parenthesis t right-parenthesis comma u prime left-parenthesis t right-parenthesis right-parenthesis comma u left-parenthesis 0 right-parenthesis equals x 0 comma u prime left-parenthesis 0 right-parenthesis equals y 0 comma">

u
(
t
)
+
A
u
(
t
)
=
F
(
t
,
u
(
t
)
,

u
′

(
t
)
)
,

u
(
0
)
=

x
0

,

u
′

(
0
)
=

y
0

,

u(t) + Au(t) = F(t,u(t),u’(t)),\quad u(0) = {x_0},u’(0) = {y_0},

\]
under minimal assumptions on the linear operator A and on the approximation spaces. A can be a very general elliptic operator (not just of 2nd order and not necessarily in a bounded domain); A can also be very singular and degenerate. The results apply also to systems of equations. Verification of the hypotheses is completely elementary for a large class of problems.
Continuous finite elements in space and time for the heat equation
Authors: Aziz A. K. , Monk Peter
Published: June 2010

In this paper we shall analyze a new variational method for approximating the heat equation using continuous finite elements in space and time. In the special case of linear elements in time the method reduces to the Crank-Nicolson Galerkin method with time-averaged data. Using higher-order finite elements in time, we obtain a new class of time stepping methods related to collocating the standard spatial Galerkin differential equations in time at the Gauss-Legendre points. Again the data enters via suitable time averages. We present error estimates and the results of some numerical experiments.
The weighted particle method for convection-diffusion equations. I. The case of an isotropic viscosity
Authors: Degond P. , Mas-Gallic S.
Published: June 2010

The aim of this paper is to present and study a particle method for convection-diffusion equations based on the approximation of diffusion operators by integral operators and the use of a particle method to solve integro-differential equations described previously by the second author. The first part of the paper is concerned with isotropic diffusion operators, whereas the second part will consider the general case of a nonconstant matrix of diffusion. In the former case, the approximation of the diffusion operator is much simpler than in the general case. Furthermore, we get two possibilities of approximations, depending on whether or not the integral operator is positive.
Error analysis of some finite element methods for the Stokes problem
Authors: Stenberg Rolf
Published: June 2010

We prove the optimal order of convergence for some two-dimensional finite element methods for the Stokes equations. First we consider methods of the Taylor-Hood type: the triangular

P
3

−

P
2

{P_3} - {P_2}

element and the

Q
k

−

Q

k
−
1

,

{Q_k} - {Q_{k - 1}},

,

k
≥
2

k \geq 2

, family of quadrilateral elements. Then we introduce two new low-order methods with piecewise constant approximations for the pressure. The analysis is performed using our macroelement technique, which is reviewed in a slightly altered form.
Iterative methods for cyclically reduced nonselfadjoint linear systems
Authors: Elman Howard C. , Golub Gene H.
Published: June 2010

We study iterative methods for solving linear systems of the type arising from two-cyclic discretizations of non-self-adjoint two-dimensional elliptic partial differential equations. A prototype is the convection-diffusion equation. The methods consist of applying one step of cyclic reduction, resulting in a "reduced system" of half the order of the original discrete problem, combined with a reordering and a block iterative technique for solving the reduced system. For constant-coefficient problems, we present analytic bounds on the spectral radii of the iteration matrices in terms of cell Reynolds numbers that show the methods to be rapidly convergent. In addition, we describe numerical experiments that supplement the analysis and that indicate that the methods compare favorably with methods for solving the "unreduced" system.
An FFT extension to the 𝑃-1 factoring algorithm
Authors: Montgomery Peter L. , Silverman Robert D.
Published: June 2010

J. M. Pollard, in 1974, presented the

P
−
1

P - 1

integer factoring algorithm. His paper couched the algorithm in theoretical terms based upon use of Fast Fourier Transform techniques, but he was unable to say whether the method could be made practical. We discuss the mathematical basis of the algorithm and show how it can work in practice. The practical implementation depends, for its success, upon the use of Residue Number Systems. We also present an open problem as to how the method could be made to work for the Elliptic Curve factoring algorithm.
Chebyshev approximations for the Fresnel integrals
Authors: Cody W. J.
Published: June 2010

Rational Chebyshev approimations have been computed for the Fresnel integrals

C
(
x
)

C(x)

and

S
(
x
)

S(x)

for arguments in the intervals

[
0.
,
1.2
]

[0.,1.2]

and

[
1.2
,
1.6
]

[1.2,1.6]

, and for the related functions

f
(
x
)

f(x)

and

g
(
x
)

g(x)

for the intervals

[
1.6
,
1.9
]

[1.6,1.9]

,

[
1.9
,
2.4
]

[1.9,2.4]

and

[
2.4
,
∞
]

[2.4,\infty ]

. Maximal relative errors range down to

2
×

10

−
19

2 \times {10^{ - 19}}

.
Effector‐triggered innate immunity contributes Arabidopsis resistance to Xanthomonas campestris
Authors: RONG WEI , FENG FENG , ZHOU JIANMIN , HE CHAOZU
Published: June 2010

Xanthomonas campestris pv. campestris, the causal agent of black rot disease, depends on its type III secretion system (TTSS) to infect cruciferous plants, including Brassica oleracea, B. napus and Arabidopsis. Previous studies on the Arabidopsis–Pseudomonas syringae model pathosystem have indicated that a major function of TTSS from virulent bacteria is to suppress host defences triggered by pathogen‐associated molecular patterns. Similar analyses have not been made for the Arabidopsis–X. campestris pv. campestris pathosystem. In this study, we report that X. campestris pv. campestris strain 8004, which is modestly pathogenic on Arabidopsis, induces strong defence responses in Arabidopsis in a TTSS‐dependent manner. Furthermore, the induction of defence responses and disease resistance to X. campestris pv. campestris strain 8004 requires NDR1 (NON‐RACE‐SPECIFIC DISEASE RESISTANCE1), RAR1 (required for Mla12 resistance) and SGT1b (suppressor of G2 allele of skp1), suggesting that effector‐triggered immunity plays a large role in resistance to this strain. Consistent with this notion, AvrXccC, an X. campestris pv. campestris TTSS effector protein, induces PR1 expression and confers resistance in Arabidopsis in a RAR1‐ and SGT1b‐dependent manner. In rar1 and sgt1b mutants, AvrXccC acts as a virulence factor, presumably because of impaired resistance gene function.
p53‐dependent G1 arrest in 1st or 2nd cell cycle may protect human cancer cells from cell death after treatment with ionizing radiation and Chk1 inhibitors
Authors: Petersen L. , Hasvold G. , Lukas J. , Bartek J. , Syljuåsen R. G.
Published: June 2010

Objectives:  This study was performed to explore the strategy of combining Chk1 inhibitors with ionizing radiation (IR) to selectively target p53‐deficient cancer cells.

Materials and methods:  Survival and cell cycle progression were measured in response to IR and the Chk1 inhibitors, UCN‐01 and CEP‐3891, in colon carcinoma HCT116 p53+/+ and p53−/− cells, and in osteosarcoma U2OS‐VP16 cells with conditional expression of dominant‐negative p53 (p53DD).

Results:  Clonogenic survival was selectively reduced in HCT116 p53−/− compared to p53+/+ cells after treatment with UCN‐01 and IR, and HCT116 p53+/+ cells also displayed strong p53‐dependent G1 arrest in the 1st cell cycle after IR. In contrast, clonogenic survival was affected similarly in U2OS‐VP16 cells with and without expression of p53DD. However, death of U2OS‐VP16 cells was p53 dependent as assessed by cell viability assay at 72 h, and this was associated with p53‐dependent G1 arrest in the 2nd cell cycle after treatment. Notably, HCT116 cells were overall more resistant than U2OS cells to cytotoxic effects of Chk1 inhibitors.

Conclusion:  Our results suggest that p53‐dependent G1 arrest in both 1st and 2nd cell cycles may protect human cancer cells from cell death after treatment with IR and Chk1 inhibitors. However, a challenge for future clinical use will be that different cancers display different intrinsic sensitivity to such inhibitors.
Differential proteome and phosphoproteome signatures in human T‐lymphoblast cells induced by sirolimus
Authors: Schultze F. C. , Petrova D. T. , Oellerich M. , Armstrong V. W. , Asif A. R.
Published: June 2010

Objectives:  The present study was designed to investigate early proteome and phosphoproteome changes during inhibition of lymphocyte proliferation induced by sirolimus (SRL).

Materials and methods:  Proliferation assays were conducted using human CCRF‐CEM T lymphoblasts under different SRL concentrations. Total protein lysates after SRL treatment were used to identify significantly regulated proteins and phosphorylated proteins by 2‐DE and Q‐TOF Ultima Global mass spectrometer.

Results and conclusions:  Incubation with 2.5 μmol/l SRL resulted in a ∼ 70% inhibition of cell proliferation. Cells incubated with 2.5 μmol/l for 30 min showed a differential phosphorylation pattern with one higher (TCPQ) and six lower phosphorylation signals (TBA1B, VIME, HNRPD, ENPL, SEPT9, PLSL). On investigating the differential protein expression, five proteins were found to be up‐regulated (ECHB, PSB3, MTDC, LDHB and NDKA) and four were down‐regulated (EHD1, AATC, LMNB1 and MDHC). Nine of these differentially regulated proteins/phosphoproteins (TCPQ, TBA1B, VIME, HNRPD, ENPL, ECHB, PSB3, LDHB and LMNB1) showed significant interaction potential, through binding protein YWHAZ using MINT software.

Conclusions:  We report for the first time the simultaneous early influence of SRL on phosphorylation status and on protein expression in the total proteome of CCRF‐CEM T lymphoblasts and predict that 56% of the proteins interact with each other, highlighting significance of these results.
Prevalence of torus palatinus among a group of Japanese elderly
Authors: YOSHINAKA M. , IKEBE K. , FURUYA‐YOSHINAKA M. , HAZEYAMA T. , MAEDA Y.
Published: June 2010

Summary  The purpose of this study was to examine the prevalence of torus palatinus (TP) among Japanese elderly and to identify the factors associated with the formation of TP. The subjects were adults aged over 60, who lived independently in the community and attended lectures once a week at the Senior Citizens’ College in Osaka prefecture during 2007 and 2008. A total of 664 subjects, including 294 men and 370 women, were examined, and the mean age was 66·5 ± 4·2 (s.d.). After informed consent was obtained, participants responded to a questionnaire and underwent clinical examination consisting of dental status, temporomandibular symptoms and occlusal force. There were 113 (17·0%) subjects with TP. The prevalence of TP was more frequent in women than in men (24·6% versus 7·5%, P < 0·01). Moreover, there was a significant relationship between the presence of TP and the presence of Torus mandibularis (13·3% versus 25·9%). There was no significant relationship between the prevalence of TP and other factors; diurnal and nocturnal bruxism, occlusal force, occlusal support and temporomandibular diseases symptom. Logistic regression analysis, in which adjustment was made for age and occlusal force, revealed a significant relationship between the presence of TP and gender and the presence of torus mandibularis (TM) (P < 0·001 OR = 3·43, 95%CI = 2·00–5·86; P < 0·001, OR = 2·63, 95%CI = 1·64–4·24, respectively). This study suggests that genetic factors play a more significant role than factors related oromaxillofacial function in the aetiology of TP.
Anterior shift in gene expression precedes anteriormost digit formation in amniote limbs
Authors: Uejima Asaka , Amano Takanori , Nomura Naoki , Noro Miyuki , Yasue Taiji , Shiroishi Toshihiko , Ohta Kunimasa , Yokoyama Hitoshi , Tamura Koji
Published: June 2010

In tetrapod limbs, an anteriormost digit has common traits of small, short and less‐phalange morphology. In this study, we focused on three genes, Mkp3, Sef and Tsukushi (TSK), which have anterior‐specific or anterior‐prominent expression patterns in the developing limb bud at the autopod‐forming stage. The anterior expression is not fixed in the period of limb development, but the expression domains of Mkp3, Sef and TSK change considerably from the distal domain to the anterior domain. This change in expression domains, anterior shift, of these genes involves maintenance of gene expression in the anterior side and downregulation in the posterior side. Manipulated overdose of fibroblast growth factor (FGF) in the presumptive digit 2 region of chick forelimb bud results in elongation of cartilage elements of digit 2, suggesting that attenuated FGF signaling, which Mkp3, Sef, and TSK negatively regulate, provides digit 2‐specific traits of morphology. The anterior expression of Mkp3 and Sef but not TSK is conserved also in limb buds of the mouse and gecko, and the anterior shift of these genes, accumulation of their transcripts in the anterior side and appropriate regulation of strength of FGF signaling may control species‐specific morphology of the anteriormost digit.
Percentage of positive biopsies predicts lymph node involvement in men with low‐risk prostate cancer undergoing radical prostatectomy and extended pelvic lymphadenectomy
Authors: Heidenreich Axel , Pfister David , Thüer David , Brehmer Bernhard
Published: June 2010

Study Type – Diagnostic (exploratory cohort) Level of Evidence 2b

What’s known on the subject? and What does the study add?

The current retrospective study evaluates predictive clinical parameters associated with lymph node metastasis in a homogeneous cohort of 499 men with low‐risk prostate cancer who underwent radical prostatectomy. Low‐risk profile and <50% of biopsies involved with cancer are strong predictors of metastasis‐free lymph nodes so that patients do not have to undergo extended pelvic lymphadenectomy.

OBJECTIVE

To evaluate preoperative predictive risk factors associated with lymph node metastases (LNM) in a cohort of low‐risk prostate cancer (PCA) patients.

PATIENTS AND METHODS

The charts of 499 patients were retrospectively reviewed to identify prognostic risk factors for the presence of LNM. Pathohistological data and Gleason score of the radical prostatectomy (RP) specimen, number of removed nodes, number of positive lymph nodes, and anatomical distribution of LNM were tabulated and evaluated. A correlation between clinical stage, preoperative serum prostate‐specific antigen (PSA), biopsy Gleason score, number of biopsies taken, percentage of positive biopsies and the presence of LNM were calculated. All 499 men underwent retropubic RP and extended pelvic lymphadenectomy (EPLND).

RESULTS

LNM were identified in 29 (5.8%) patients. A prediction model based on clinical stage, PSA, and biopsy Gleason score had a predictive accuracy of 79.2%. The addition of number of positive biopsies and % positive cores improved its predictive accuracy to 81.5% and 87.8%, respectively. The predicted frequency of LNM by the original nomogram was 7.4% and differed by less than 3% with the actual observation of LNM. The predictive accuracy of the nomogram was 81.5% as compared with 87.8% of the prediction model of this study.

CONCLUSIONS

The percentage of positive cores involved with PCA is the most reliable predictor of LNM and indicates the need for EPLND. The Briganti nomogram has been validated and a general applicability for predicting the presence of LNM was proven.
Cardiovascular dysautonomia in de novo Parkinson’s disease without orthostatic hypotension
Authors: Oka H. , Toyoda C. , Yogo M. , Mochio S.
Published: June 2010

Background:  Clinical symptoms of Parkinson’s disease (PD) include not only motor distress, but also autonomic dysfunction.

Objective:  To study the characteristics of subclinical autonomic nervous dysfunction in de novo PD without orthostatic hypotension (OH).

Methods:  Autonomic nervous function including cardiac sympathetic gain was evaluated on the basis of cardiac radioiodinated metaiodobenzylguanidine (MIBG) uptake, the response to the Valsalva maneuver, and spectral analyses of the RR interval and blood pressure in 20 patients with de novo PD without OH.

Results:  Decreased cardiac MIBG uptake was found even in patients with PD without OH. Hemodynamic studies using the Valsalva maneuver revealed that patients with PD without OH had preserved baroreceptor reflex sensitivity in phase II and phase IV. Blood pressures normally responded in early and late phase II, but not in phase IV. Blood pressure recovery time was slightly reduced in patients with PD without OH when compared with the value in controls. The low frequency component of the RR interval and systolic blood pressure and the ratio of RR‐LF to RR‐HF in de novo PD without OH were significantly reduced when compared with the control values, whereas the high frequency component of the RR interval did not differ significantly.

Conclusion:  These results show that latent cardiac and vasomotor sympathetic dysfunction but not parasympathetic dysfunction is already present in early stage de novo PD, even without orthostatic hypotension.
Distribution, clinical correlates and significance of axonal loss and demyelination in chronic inflammatory demyelinating polyneuropathy
Authors: Rajabally Y. A. , Narasimhan M.
Published: June 2010

Background:  The distribution of axonal loss and demyelination has rarely been studied in chronic inflammatory demyelinating polyneuropathy (CIDP). Whether electrophysiological parameters may represent clinically relevant biomarkers of disease activity in the disorder remains uncertain. The purpose of this study was (i) to ascertain the distribution of electrophysiological motor abnormalities to optimize the diagnostic utility of nerve conduction studies and (ii) to establish electro‐clinical correlations in an attempt to find the potential parameters that could represent adequate biomarkers of disease activity and prognosis.

Methods:  The clinical and electrophysiological motor features of 31 prospectively recruited patients with clinically stabilized CIDP were analysed.

Results:  Axonal loss predominated in the lower limbs, but demyelination was more common in the upper limbs. About 50% of all demyelinating abnormalities were detected in asymptomatic regions. Presence of weakness correlated with abnormal compound muscle action potential (CMAP) and abnormal motor nerve conduction velocity (MNCV). Degree of weakness and functional scores only consistently correlated with CMAP amplitudes. CMAP abnormality correlated with abnormal MNCV, abnormal distal motor latency (DML) and presence of conduction block (CB). However, although CMAP amplitudes also correlated with MNCVs and DMLs in raw values, they did not relate to the degree of CB.

Conclusion:  Electrodiagnosis of CIDP is optimized by extensive testing of upper limb nerves and of asymptomatic regions. Raw value CMAP amelioration and MNCV normalization may be adequate markers of clinical improvement in CIDP. Similarly, raw value MNCV and DML amelioration, as well as CB reversal may represent adequate prognostic markers.
Sources of information on adverse effects: a systematic review
Authors: Golder Su , Loke Yoon K.
Published: June 2010

Background: Systematic reviews can provide accurate and timely information on adverse effects. An essential part of the systematic review process is a thorough search of the literature. This often requires searching many different sources. However, it is unclear which sources are most effective at providing information on adverse effects.

Objective: To identify and summarise studies that have evaluated sources of information on adverse effects.

Methods: Studies were located by searching in 10 databases as well as by reference checking, hand searching, citation searching and contacting experts.

Results: A total of 6218 citations were retrieved yielding 19 studies which met the inclusion criteria. The included studies tended to focus on the adverse effects of drug interventions and compare the relative value of different sources using the number of relevant references retrieved from searches of each source. However, few studies were conducted recently with a large sample of references.

Conclusions: This review suggests thatembase, Derwent Drug File,medlineand industry submissions may potentially provide the greatest number of relevant references for information on adverse effects of drugs. However, a systematic evaluation of the current value of different sources of information for adverse effects is urgently required.
Interactions of nerve agents with model surfaces: Computational approach
Authors: Michalkova A. , Leszczynski J.
Published: June 2010

The development of cost effective, cleanup technologies for organophosphorus contaminants continue to be a high priority for environmental restoration research. Such development involves the coordination of experimental and theoretical investigations to understand and integrate both technological and fundamental aspects of key processes. Although the major processes affecting the natural and engineered treatment of organophosphates have been appreciated qualitatively, many questions remain regarding their reaction mechanisms. Unique properties of clay minerals and metal oxides such as high adsorption and catalytic ability have resulted in their applications as natural adsorbents and catalysts in the development of cleanup technologies. An understanding of the physical and chemical characteristics of the contaminants, adsorption sites of selected catalytic materials, details of sorption of contaminants on soil, on soil in water solution, and also their distribution within the environment is of particular interest. Application of computational chemistry can provide deeper insight into the aforementioned characteristics of organophosphorus compounds as is discussed in this article. Theoretical models were developed that explain and predict how clay minerals and metal oxides, their type and size, and adsorption site can affect the adsorption and decomposition of selected nerve agents and their simulants, and the influence on many factors including the presence of cations, water, and different used computational methods and techniques was analyzed. Several different initial positions and orientations of organophosphate molecules on models of metal oxides and clays were tested. The results show that the small fragments of metal oxides and clay minerals are much more reactive toward the adsorption of organophosphates which under certain conditions can lead to their decomposition. On the other hand, decrease in ionicity of metal oxides results in lowering of the binding affinity toward such compounds.
Study on MoO3−x films deposited by reactive sputtering for organic light-emitting diodes
Authors: Oka Nobuto , Watanabe Hiroki , Sato Yasushi , Yamaguchi Hiroshi , Ito Norihiro , Tsuji Hiroya , Shigesato Yuzo
Published: June 2010

The authors investigate the role of reduced molybdenum trioxide [MoO3−x (x≤1)] films in organic light-emitting diodes, particularly from the viewpoint of the oxidation state of Mo. MoO3−x films were deposited by reactive sputtering under a mixture of argon (Ar) and oxygen (O2). The O2 gas-flow ratio (GFR) [O2/(Ar+O2)] was adjusted between 10% and 100%. Mo with six, five, and four valence electrons was detected in MoO3−x film deposited with an O2 GFR of 10% and 12.5%, whereas, under higher O2 GFRs, only six valence electrons for Mo in the MoO3−x film were detected. N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine (α-NPD) layer, hole-transport material, were deposited over the MoO3−x layer by subsequent vacuum evaporation. At the α-NPD/MoO3−x interface, it was found that α-NPD cations were generated and that MoO3−x was reduced, which provided evidence of charge transfer across the interface by Raman spectroscopy and x-ray photoelectron spectroscopy.
Fabrication of ZnO photonic crystals by nanosphere lithography using inductively coupled-plasma reactive ion etching with CH4/H2/Ar plasma on the ZnO/GaN heterojunction light emitting diodes
Authors: Chen Shr-Jia , Chang Chun-Ming , Kao Jiann-Shiun , Chen Fu-Rong , Tsai Chuen-Horng
Published: June 2010

This article reports fabrication of n-ZnO photonic crystal/p-GaN light emitting diode (LED) by nanosphere lithography to further booster the light efficiency. In this article, the fabrication of ZnO photonic crystals is carried out by nanosphere lithography using inductively coupled plasma reactive ion etching with CH4/H2/Ar plasma on the n-ZnO/p-GaN heterojunction LEDs. The CH4/H2/Ar mixed gas gives high etching rate of n-ZnO film, which yields a better surface morphology and results less plasma-induced damages of the n-ZnO film. Optimal ZnO lattice parameters of 200 nm and air fill factor from 0.35 to 0.65 were obtained from fitting the spectrum of n-ZnO/p-GaN LED using a MATLAB code. In this article, we will show our recent result that a ZnO photonic crystal cylinder has been fabricated using polystyrene nanosphere mask with lattice parameter of 200 nm and radius of hole around 70 nm. Surface morphology of ZnO photonic crystal was examined by scanning electron microscope.
Imaging characterization techniques applied to Cu(In,Ga)Se2 solar cells
Authors: Johnston Steve , Unold Thomas , Repins Ingrid , Sundaramoorthy Rajalakshmi , Jones Kim M. , To Bobby , Call Nathan , Ahrenkiel Richard
Published: June 2010

The authors present examples of imaging characterization on Cu(In,Ga)Se2 (CIGS) solar cell devices. These imaging techniques include photoluminescence imaging, electroluminescence imaging, illuminated lock-in thermography, and forward- and reverse-bias dark lock-in thermographies. Images were collected on CIGS devices deposited at the National Renewable Energy Laboratory with intentional spatial inhomogeneities of the material parameters. Photoluminescence imaging shows brightness variations, which correlate to the device open-circuit voltage. Photoluminescence and electroluminescence imaging on CIGS solar cells show dark spots that correspond to bright spots on images from illuminated and forward-bias lock-in thermography. These image-detected defect areas are weak diodes that conduct current under solar cell operating conditions. Shunt defects are imaged using reverse-bias lock-in thermography. The authors show how imaging can be used to detect structural defects detrimental to solar cell performance. The images provide defect locations that are analyzed in more detail by scanning electron microscopy techniques using top view and cross section imaging.
Orientation-dependent ion beam sputtering at normal incidence conditions in FeSiAl alloy
Authors: Batič Barbara Šetina , Jenko Monika
Published: June 2010

The authors have performed Ar+ broad ion beam sputtering of a polycrystalline Fe–Si–Al alloy at normal incidence at energies varying from 6 to 10 keV. Sputtering results in the formation of etch pits, which can be classified in three shapes: triangular, rectangular, and square. As each grain of individual orientation exhibits a certain type of pattern, the etch pits were correlated with the crystal orientations by electron backscattered diffraction technique.
Triboelectrification studies of skin and skin cream using Kelvin probe microscopy
Authors: Tang Wei , Bhushan Bharat , Ge Shirong
Published: June 2010

Static charge of skin surface has a significant effect on skin feel, look, and health. For this reason, controlling the charge buildup is an important issue in the commercial skin care industry. In this study, a systematic triboelectrification study of skin and skin cream was carried out. The surface potential of virgin skin and cream treated skin was measured using the Kelvin probe microscopy with an atomic force microscope. Since skin surface is not microscopically smooth, many interactions take place at microasperities, and there are also many microspherical particles in the environment interacting with skin surface. Triboelectrification of skin was studied by charging skin surface using a polystyrene plate on the macroscale and a polystyrene microsphere on the microscale. Since triboelectric charge is expected to be a function of normal load, velocity, and rubbing time, the influence of velocity, normal load, and rubbing time on the surface potential of virgin skin and cream treated skin were studied. Finally, charging mechanisms are discussed.
Scaling behaviors of silicon-nitride layer for charge-trapping memory
Authors: Li Dong Hua , Yun Jang-Gn , Lee Jung Hoon , Park Byung-Gook
Published: June 2010

The authors investigate the scaling behaviors of a silicon-nitride layer for use in a charge-trapping memory device according to dimension downscaling of the memory-device cells. As is known, charge storage takes place in discrete traps in the silicon-nitride layer. In this study, a 5-nm-thick charge-storage layer in the conventional oxide-nitride-oxide device is investigated and shows considerable trap-based memory characteristics, but encounters a retention problem. Therefore, they adopt a modulated tunnel barrier to replace the single tunnel oxide so as to improve the charge-retention property. As a result, experimental results show excellent memory program/erase operation behaviors and indicate further scalability of the charge-storage layer compared to the conventional oxide-nitride-oxide device.
Imprinting of guide structure to weave nylon fibers
Authors: Mekaru Harutaka , Takahashi Masaharu
Published: June 2010

The authors have proposed electrical circuits accumulated by injecting electroconductive materials into patterns imprinted on the surface of fibers and weaving the fibers like a mesh. For these circuits, a built-in guide structures, which determine the positions where the fibers are to make contact with each other and exchange pertinent information, must be fabricated on fibers. In the experiments, a concave 21-μm-deep structure to serve as weaving guide was processed on the surface of 90-μm-diameter nylon fibers by thermal imprinting with a plane mold. The guides were made with two types of cross sections: rectangular and arc shaped. The rectangular structure was fabricated by a combination of microelectromechanical systems processing and Ni-electroforming technologies, whereas the arc-shaped structure involved dicing and fine machining operations. These structures on molds were designed to imprint weaving-guide structures on fibers with arrays of poles (20 μm in diameter and 10 μm in height) at their bottom to serve as fixation points for fibers and to make electric contacts after metallization. Both types of molds were made with a two-step structure that could be transferred on fibers in one single stamping operation. In thermal imprint experiments, to speed things up, the contact time was set for 1 s only. In order to compensate for the short contact time, the heating temperature was set at 100 °C, which is 50 °C higher than the glass transition temperature of nylon. Regardless of the type of mold, weaving guides and contact supports were successfully formed on the surface of nylon fibers. Thus, the capability to process complex microstructures by thermal nanoimprinting on the surface of fine fibers was experimentally proven. Moreover, the authors report on the results of the trial run for weaving imprinted nylon fibers to form fabrics.
Monoclinic textured HfO2 films on GeOxNy/Ge(100) stacks using interface reconstruction by controlled thermal processing
Authors: Bastos Karen Paz , Miotti Leonardo , Lucovsky Gerald , Chung Kwun-Bum , Nordlund Dennis
Published: June 2010

The authors used x-ray absorption spectroscopy of the O K edge to investigate the nanocrystalline structure of thin HfO2 films deposited by remote plasma enhanced chemical vapor deposition on Ge(100). Postdeposition thermal process induced the interfacial reconstruction and the crystallization of the HfO2 in the monoclinic structure driven by the Ge(100) substrate. The substrate templating of the HfO2 crystallization is an evidence that the processing used here removes the undesired the interfacial layer and has the potential to yield interfaces with low density of defects.
Numerical ellipsometry: Analysis of thin metal layers using n-k-d twisted curve methods with multiple incidence angles
Authors: Urban F. K. , Barton D. , Tiwald T.
Published: June 2010

A major challenge for those utilizing ellipsometry is numerical processing of the measured data. The transcendental, multivalued equations arising from the physics of simple reflection are problematic for the least-squares numerical methods in common use. These early numerical methods require fairly accurate initial estimates, bounding to avoid local minima, and only find solutions at the bottom of a relatively flat numerical topography. Previously the authors have applied complex analysis in the n-k plane to improve visualization of the mathematics, and this has led to a growing array of new numerical methods avoiding these difficulties. The work presented here extends these new numerical methods to three dimensions (n-k-d space) for use with absorbing films deposited on transparent and on absorbing substrates. The method finds intersections of three “twisted curves” resulting from three (or more) light incidence angle measurements per wavelength. The method is employed here to determine the thickness and optical properties of chromium films (between 10 and 25 nm nominal thickness) deposited onto two different substrates, silicon and silica oxide, employing measurements made at three different angles of incidence for light wavelengths between 280 and 2500 nm.
Ferrimagnetic ordering of single crystal Fe1−xGax thin films
Authors: McClure Adam , Arenholz E. , Idzerda Y. U.
Published: June 2010

Molecular beam epitaxy was used to deposit body centered cubic single crystal Fe1−xGax thin films on MgO(001) and ZnSe/GaAs(001) substrates well beyond the bulk stability concentration of about 28%. The crystal quality of the substrate surface and each deposited layer was monitored in situ by reflection high energy electron diffraction. The magnetization of the samples as a function of Ga is found to decrease more rapidly than a simple dilution effect, and element-specific x-ray magnetic circular dichroism ascribes this trend to a decrease in the Fe moment and an induced moment in the Ga that is antialigned to the Fe moment.
Effectiveness of passivation techniques on hydrogen desorption in a tritium environment
Authors: Woodall Steven , Pines Edward , Valles-Rosales Delia
Published: June 2010

Tritium is a radioactive isotope of hydrogen. It is used as a fuel in fusion reactors, a booster material in nuclear weapons, and as a light source in commercial applications. When tritium is used in fusion reactors, and especially when used in the manufacture of nuclear weapons, purity is critical. For U.S. Department of Energy use, tritium is recycled by the Savannah River Site in South Carolina and is processed to a minimum purity of 99.5%. For use elsewhere in the country, it must be shipped and stored, while maintaining the highest purity possible. As an isotope of hydrogen, it exchanges easily with the most common isotope of hydrogen, protium. Stainless steel bottles are used to transport and store tritium. Protium, present in air, becomes associated in and on the surface of stainless steel during and after the manufacture of the steel. When filled, the tritium within the bottle exchanges with the protium in and on the surface of the stainless steel, slowly contaminating the pure tritium with protium. The stainless steel is therefore passivated to minimize the protium outgrowth of the bottles into the pure tritium. This research is to determine how effective different passivation techniques are in minimizing the contamination of tritium with protium. Additionally, this research will attempt to determine a relationship between surface chemistry of passivated steels and protium contamination of tritium. The conclusions of this research found that passivated bottles by two companies, which routinely provide passivated materials to the U.S. Department of Energy, provide low levels of protium outgrowth into pure tritium. A bottle passivated with a material to prevent excessive corrosion in a highly corrosive environment, and a clean and polished bottle provided outgrowth rates roughly twice those of the passivated bottles above. Beyond generally high levels of chromium, oxygen, iron, and nickel in the passivated bottles, there did not appear to be a strong correlation between surface chemistry in the surface of the bottles and protium outgrowth rates.
Sticks and Stones and Mending Bones
Authors: Ng Kenneth W.
Published: June 2010

Prevascularized bone grafts may speed up bone healing in trauma or fractures with serious complications.
Identification of human enzymes oxidizing a human metabolite of carcinogenic 2-nitroanisole, 2-nitrophenol. Evidence for its oxidative detoxification by human cytochromes P450
Authors: Svobodová Martina , Martínková Markéta , Frei Eva , Stiborová Marie
Published: June 2010

2-Nitrophenol (2-NP) is the major detoxification metabolite of an important industrial pollutant and a potent carcinogen, 2-nitroanisole (2-NA). Here, we characterized the product of 2-NP metabolism catalyzed by human, rat, rabbit and mouse hepatic microsomes containing cytochromes P450 (CYPs) and identified the major human CYP enzymes participating in this process. The 2-NP metabolite was characterized by mass spectrometry and co-chromatography on HPLC with a synthetic standard, 2,5-dihydroxynitrobenzene (2,5-DNB) to be 2,5-DNB. No nitroreductive metabolism leading to the formation ofN-(2-hydroxyphenyl)hydroxylamine oro-aminophenol was evident by all tested hepatic microsomes. Likewise, no DNA binding of 2-NP metabolite(s) measured with the32P-postlabeling technique was detectable in hepatic microsomes. Therefore, hepatic microsomal CYP enzymes participate in 2-NP metabolism that does not lead to its activation to species binding to DNA. Selective inhibitors of human CYPs were used to characterize CYPs oxidizing 2-NP in human livers. Based on these inhibitory studies, we attribute most of 2-NP oxidation in human liver to CYP2E1, 3A4, 2A6, 2C and 2D6. Among recombinant human CYP enzymes tested in this study, CYP2E1, 2A6 and 2B6 were the most effective enzymes oxidizing 2-NP. Oxidation of 2-NP by human CYP2E1 exhibits the Michaelis-Menten kinetics, having theKm value of 0.21 mM. The results found in this study, the first report on the metabolism of 2-NP by human hepatic microsomes and human CYP enzymes, demonstrate that CYP2E1 is the major enzyme oxidizing this compound in human.
Relation between Helicobacter pylori infection and gastrointestinal symptoms and syndromes
Authors: Rosenstock S , Kay L , Rosenstock C , Andersen L P , Bonnevie O , Jørgensen T
Published: June 2010

Background—Helicobacter pylori is a human pathogen that colonises the gastric mucosa and causes permanent gastric inflammation.

Aims—To assess the symptoms of H pylori infection in an adult unselected population.

Subjects—A random sample of 3589 adult Danes who were examined in 1982 and 1987 (n=2987).

Methods—Abdominal symptoms within the preceding year were recorded at both attendances. Circulating IgG antibodies against H pylori in serum samples drawn in 1982 were measured by using in-house indirect enzyme linked immunosorbent assays (ELISA).

Results—People with increased levels of IgG antibodies to H pylori were more likely than uninfected individuals to report heartburn (odds ratio (OR) = 1.26, 95% confidence interval (CI) 1.03–1.54) and abdominal pain characterised by daily length (OR = 1.33, 95% CI 0.92–1.91), nocturnal occurrence (OR = 1.62, 95% CI 1.19–2.19), spring aggravation (OR = 1.68, 95% CI 0.70–4.05), and no relation to meals (OR = 0.62, 95% CI 0.43–0.91) or stress (OR = 0.69, 95% CI 0.50–0.95). The inclusion of people with increased levels of IgG antibodies to H pylori, but without upper dyspepsia, at study entry significantly increased the likelihood of reporting upper dyspepsia at follow up (OR = 1.71, 95% CI 1.24–2.36). People with epigastric pain and increased levels of IgM antibodies to H pylori only indicative of acute H pylori infection were more likely to report nocturnal pain, heartburn, nausea, and vomiting.

Conclusions—H pylori infection may precede the development of dyspepsia and is associated with a variety of gastrointestinal symptoms in people with no history of peptic ulcer disease.
Increased expression of transforming growth factor α precursors in acute experimental colitis in rats
Authors: Hoffmann P , Zeeh J M , Lakshmanan J , Wu V S , Procaccino F , Reinshagen M , McRoberts J A , Eysselein V E
Published: June 2010

Background and aim—Epidermal growth factor (EGF) and transforming growth factor α (TGF-α), members of the EGF family of growth factors, protect rat gastric and colonic mucosa against injury. Having shown previously that exogenously applied EGF protects rat colonic mucosa against injury, the aim of the present study was to evaluate the endogenously expressed ligand mediating the protective effect of EGF/TGF-α in vivo.

Methods—In an experimental model of trinitrobenzene sulphonic acid (TNBS)/ ethanol induced colitis in rats EGF and TGF-α expression was evaluated using a ribonuclease protection assay, northern blot analysis, western blot analysis, and immunohistochemistry.

Results—TGF-α mRNA increased 3–4 times at 4–8 hours after induction of colitis and returned to control levels within 24 hours. TGF-α immunoreactive protein with a molecular size of about 28 kDa representing TGF-α precursors increased markedly after induction of colitis with a peak at 8–12 hours. No fully processed 5.6 kDa TGF-α protein was detected in normal or inflamed colon tissue. Only a weak signal for EGF mRNA expression was detected in the rat colon and no EGF protein was observed by immunohistochemistry or western blot analysis.

Conclusions—TGF-α precursors are the main ligands for the EGF receptor in acute colitis. It is hypothesised that TGF-α precursors convey the biological activity of endogenous TGF-α peptides during mucosal defence and repair.
Peutz-Jeghers polyps, dysplasia, and K-ras codon 12 mutations
Authors: Entius M M , Westerman A M , Giardiello F M , van Velthuysen M-L F , Polak M M , Slebos R J C , Wilson J H P , Hamilton S R , Offerhaus G J A
Published: June 2010

Background—Peutz-Jeghers syndrome (PJS) is a rare, autosomal dominant, polyposis syndrome, associated with an increased risk of gastrointestinal and extragastrointestinal malignancy. Occasionally dysplasia occurs in PJS polyps.

Aims—In colorectal carcinomas, mutations in codon 12 of the K-ras oncogene are common and are found at similar frequency in precursor adenomas. Therefore, K-rascodon 12 point mutations in PJS polyps were evaluated.

Materials and methods—Fifty two PJS polyps, including four with dysplasia, collected from 19 patients with PJS, were analysed for mutations in the K-ras codon 12 by a mutant enriched polymerase chain reaction procedure, followed by allele specific oligodeoxynucleotide hybridisation.

Results—A K-ras codon 12 mutation was identified in one colonic polyp with dysplasia. The mutation was found in the non-neoplastic epithelial cells and not in the dysplastic component of the polyp.

Conclusions—K-ras codon 12 point mutations are very rare in PJS polyps, by contrast with colorectal adenomas. The findings support previous evidence that there seems to be no intrinsic relation between K-ras codon 12 mutation and dysplasia.
Prediction of recurrent choledocholithiasis by quantitative cholescintigraphy in patients after endoscopic sphincterotomy
Authors: Lai K H , Peng N J , Lo G H , Cheng J S , Huang R L , Lin C K , Huang J S , Chiang H T , Ger L P
Published: June 2010

Background—Endoscopic sphincterotomy (EST) is widely used for the removal of stones from the bile duct, but stones recur in about one fifth of patients.

Aims—To investigate hepatic clearance by quantitative cholescintigraphy (QC) in patients after EST and to discern the relationship between biliary emptying and stone recurrence.

Methods—One hundred and forty nine patients who had EST and clearance of the bile duct for choledocholithiasis were selected. All patients were confirmed to have complete EST by sphincter of Oddi manometry and underwent QC soon after normalisation of liver function. Regular clinical follow up was performed for each patient.

Results—During a mean 36 month follow up, 22 (14.8%) patients developed recurrent stones in the bile duct. Irrespective of the status of the gall bladder, patients with recurrent stones had a slower hepatic clearance of radioisotope during QC compared with patients without stone recurrence, but only the differences in cholecystectomised patients had statistical significance. After carrying out multivariate analysis, one parameter of QC, percentage clearance of maximal count at 45 minutes, was found to be the only significant factor for stone recurrence. All recurrent stones in the common bile duct were successfully removed at endoscopy.

Conclusion—Slower hepatic clearance as shown by QC is an important factor responsible for stone recurrence after sphincter ablation.