bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of calcium and cellular permeabilization on the structure of the parenchyma of osmotic dehydrated ‘Granny Smith’ apple
Authors: Quiles Amparo , Hernando Isabel , Pérez‐Munuera Isabel , Llorca Empar , Larrea Virginia , Ángeles Lluch M
Published: August 2004

Calcium plays a very important role in the maintenance of quality in vegetable foods and it is used as a texturing agent to preserve the structure of minimally processed vegetables. The osmotic dehydration (OD) of ‘Granny Smith’ apple parenchyma by immersion in a sucrose solution allows us to obtain products with sensorial characteristics similar to those of fresh products, but it produces a loss of cellular integrity. Here we study the use of calcium as a possible preservative for the microstructural integrity of the product during OD, as well as to test whether cellular permeabilization improves the impact of calcium on the edible parenchyma of the ‘Granny Smith’ apple. Sodium dodecyl sulfate (SDS) has been used for convenience as a permeating agent although we recognize this may not be used in practice. The microstructure of the OD apple treated with calcium chloride and with SDS has been compared with fresh apple by means of light microscopy, transmission electron microscopy and low temperature scanning electron microscopy. The results show that calcium has a protective effect on the structural integrity during OD: it strengthens the cellular walls cements, avoids cellular collapse and protects protoplasts from plasmolysis. Although SDS favours calcium penetration, its use is not advisable since it encourages the destructuring effect of the OD and counteracts the consolidating effect of calcium. Copyright © 2004 Society of Chemical Industry
Flavonoid glycosides and antioxidant capacity of various blackberry, blueberry and red grape genotypes determined by high‐performance liquid chromatography/mass spectrometry
Authors: Cho Mi Jin , Howard Luke R , Prior Ronald L , Clark John R
Published: August 2004

Anthocyanin and flavonol glycosides of various blackberry, blueberry and red wine grape genotypes were identified and measured by a high‐performance liquid chromatographic (HPLC) separation method with photodiode array (PDA) and mass spectrometric (MS) detection. With this method, two distinct elution regions of anthocyanins and flavonols were obtained with near baseline separation of most compounds. Blackberry, blueberry and red wine grape genotypes varied markedly in total anthocyanins and total flavonols as well as oxygen radical absorbance capacity (ORAC). The respective ranges of total anthocyanin (TA) and total flavonol (TF) contents of tested samples were: blackberries, 1143.9–2415.4 and 102.0–160.2 mg kg−1; blueberries, 1435.2–8227.3 and 172.5–327.5 mg kg−1; and red wine grapes, 380.9–7904.7 and 21.0–322.2 mg kg−1. Antioxidant activities and contents of total anthocyanins and total flavonols in blackberries, blueberries and red wine grapes were highly correlated, with linear relationships between ORAC and TA (rxy = 0.94) and TF (rxy = 0.90) for grapes, TA (rxy = 0.95) for blueberries and TA (rxy = 0.74) for blackberries. Copyright © 2004 Society of Chemical Industry
Storage and ultraviolet‐induced tissue stress effects on fresh‐cut pineapple
Authors: Lamikanra Olusola , Richard Olga A
Published: August 2004

The effect of UV‐induced stress on the volatile aroma compounds in cut pineapple was compared with that of storage at 4 °C for 24 h. Eighteen volatile compounds were identified by solid‐phase microextraction (SPME) in fresh‐cut pineapple. Methyl‐2‐methylbutanoate, methyl hexanoate, methyl 5‐hexenoate, ethyl hexanoate and ethyl 5‐hexenoate were the major aroma compounds. Storage at 4 °C for 24 h, and exposure of cut fruit to UV radiation for 15 min caused a considerable decrease in the concentration of esters and increase in the relative amount of copaene. This sesquiterpene, when added to crushed cantaloupe melon (0.1 mg g−1), inhibited microbial growth in the fruit over a period of 24 h at 20 °C.Cis‐ andtrans‐ocimene were present in the fruit but their production was not photo‐induced by UV irradiation. Ocimene, however, was a potent antimicrobial agent that killed microorganisms when added to the crushed fruit and stored at 20 °C for 24 h. The results indicate that sesquiterpene phytoalexins could contribute to the defense mechanism in wounded pineapple tissue. Published in 2004 for SCI by John Wiley & Sons, Ltd.
Influence of exogenous enzyme supplementation on energy utilisation and nutrient digestibility of cereals for broilers
Authors: Wu YB , Ravindran V , Hendriks WH
Published: August 2004

The influence of a microbial phytase, produced by solid‐state fermentation, on the apparent metabolisable energy and ileal digestibility of phosphorus, nitrogen and starch in sorghum, maize, wheat and barley was examined using 4‐week‐old broilers. For wheat and barley, the influence of phytase, individually or in combination with glycanases, was also evaluated. Microbial phytase improved (p < 0.05) apparent ileal phosphorus digestibility in all cereals. Phytase supplementation improved (p < 0.05) the apparent metabolisable energy of maize and barley by 2.6 and 7.8%, respectively. Numerical improvements in apparent metabolisable energy were observed in sorghum (1.9%) and wheat (2.1%), but were not statistically significant (p > 0.05). Further improvements (p < 0.05) in the apparent metabolisable energy of wheat and barley were observed when the phytase was combined with glycanases. However, the observed improvements in apparent metabolisable energy were not always associated with enhanced ileal digestibility of protein and starch. Copyright © 2004 Society of Chemical Industry
In vitro and in vivo digestibility of the albumin and globulin fractions of eight Brazilian cowpea [Vigna unguiculata (L) Walp] cultivars
Authors: Oliveira Jose TA , Pinto Vicente PT , Vasconcelos Ilka M , Fernandes Cléberson F , Ramos Márcio V , Ferreira Francisco VA , Rios Francisco JB
Published: August 2004

Cowpea (Vigna unguiculata) is a very important crop for people living in the north‐east of Brazil where it constitutes the principal source of protein and carbohydrate. In this study, it was observed that the in vitro digestibility of the seed albumin and globulin fractions extracted from eight Brazilian cowpea cultivars was high when treated with pepsin but resistant to degradation by trypsin or chymotrypsin even after 3 h of treatment. When the albumin and globulin fractions were given to rats by intragastric intubation it was observed that intact proteins or their fragments were immunodetected in the faeces. Immunohistochemical analyses of the gut sections of these rats showed that a proportion of the albumin fraction (or its fragments), but not the globulin one, was bound to the brush border enterocytes in the duodenum. Thus the incomplete enzymatic degradation of both globulin and albumin fractions as well as the albumin binding to the gut may have a bearing upon the growth depression, malabsorption and diarrhoea observed on rats fed on cowpea seeds. Copyright © 2004 Society of Chemical Industry
Changes in purified tomato pectinmethylesterase activity during thermal and high pressure treatment
Authors: Verlent Isabel , Loey Ann Van , Smout Chantal , Duvetter Thomas , Nguyen Binh Ly , Hendrickx Marc E
Published: August 2004

The enzymatic reaction of purified tomato pectinmethylesterase on pectin was investigated during a combined high pressure/temperature treatment (0.1–600 MPa/20–65 °C) at pH 8.0 and pH 4.4. The optimal temperature for tomato pectinmethylesterase activity at atmospheric pressure is situated around 45 °C at pH 8.0, and around 35 °C at pH 4.4. At both pH 8.0 and pH 4.4, the optimal temperature shifted to higher values at elevated pressure compared with atmospheric pressure. At both pH values, the catalytic activity of tomato pectinmethylesterase was higher at elevated pressure than at atmospheric pressure, creating possibilities for rheology improvements by pressure processing. Maximal tomato pectinmethylesterase activity in the pressure–temperature domain investigated was observed at 55 °C and 300 MPa for pH 8.0 and at 57 °C and 450 MPa for pH 4.4. However, under all pressure–temperature conditions tested the catalytic activity of tomato pectinmethylesterase at pH 4.4 was much lower than at pH 8.0. The chemical de‐esterification of pectin at pH 8.0 was accelerated by increasing pressure and temperature, whereas no chemical deesterification of pectin was observed at pH 4.4. Copyright © 2004 Society of Chemical Industry
Quadratic algebraic numbers with finite b‐adic expansion on the unit circle and their distribution
Authors: Dorfer Gerhard , Tichy Robert F.
Published: August 2004

We consider elements x + y$ \sqrt {-m} $ in the imaginary quadratic number field ℚ($ \sqrt {-m} $) such that the norm x2 + my2 = 1 and both x and y have a finite b–adic expansion for an arbitrary but fixed integer base b. For m = 2, 3, 7 and 11 a full description of this set is given. Ordered by the number of digits in the b–adic expansion of the coordinates, the corresponding sequence of points on the unit circle, if infinite, is uniformly distributed. This continues work of P. Schatte who treated the case m = 1. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Axonal excitability measured by tracking twitch contraction force
Authors: Trevillion Louise , Howells James , Jankelowitz Stacey , Burke David
Published: August 2004

The present study addressed whether the excitability of motor axons could be documented by tracking a target submaximal contraction force rather than a target submaximal compound muscle action potential (CMAP). In 10 subjects, multiple excitability measures were recorded using the Trond protocol, tracking twitch contraction force and the CMAP in response to stimulation of the median nerve at the wrist and twitch force to stimulation at the motor point. With stimulation at the wrist, the findings were virtually identical with force tracking and CMAP tracking for indices dependent on unconditioned thresholds (stimulus–response curves; strength–duration properties) and when the conditioning stimulus was subthreshold (threshold electrotonus; current–threshold relationship). However, when the conditioning stimulus was supramaximal, as in recovery cycle studies, thresholds for the target force were lower in all subjects than for the target CMAP. There was variability between different subjects in the extent of this offset. However, force tracking can still be used to follow changes in refractoriness and supernormality when membrane potential changes during an experiment. The excitability indices differed with motor point stimulation, but it is argued that this could be due to the geographic dispersion of motor axons at the motor point in addition to or instead of differences in biophysical properties of the stimulated nodes. Thus, tracking twitch contraction force is a potentially valuable alternative to tracking the CMAP, but is more complicated and the results need to be interpreted with caution. Muscle Nerve 30: 437–443, 2004
Acute multiple cranial neuropathy: A variant of Guillain–Barré syndrome?
Authors: Lyu Rong‐Kuo , Chen Sien‐Tsong
Published: August 2004

Three patients with acute multiple cranial neuropathy following benign infectious disease are reported. Complete or partial ophthalmoplegia, as well as facial and bulbar dysfunction, were noted in all. Cranial nerve involvement was bilateral. Other neurological deficits included sensory loss in two patients and transiently reduced tendon reflexes in the left arm in one. One patient had positive serum anti‐GQ1b immunoglobulin G antibody during the acute phase of the illness. The cerebrospinal fluid had a normal cell count in all three patients, with raised protein concentrations in two. Electrophysiological evaluation showed peripheral nerve dysfunction in two patients. All three patients improved either spontaneously or coincident with immunotherapy. Our patients had many clinical features resembling those of typical Guillain–Barré syndrome (GBS), and hence their disorder may represent a regional variant, that is, a cranial form, of GBS. This form of GBS accounted for 5% of the GBS patient population in our series. Muscle Nerve 30: 433–436, 2004
Validity of three calliper‐based transrectal ultrasound methods and digital rectal examination in the estimation of prostate volume and its changes with age: The Krimpen study
Authors: Bosch J.L.H.R. , Bohnen A.M. , Groeneveld F.P. , Bernsen R.
Published: August 2004

Background

Prostate volume and its changes are important parameters in studies of the natural history of benign prostatic hyperplasia (BPH), for prediction of treatment effect and the risk of adverse outcomes. The validity of three calliper‐based transrectal ultrasound (TRUS) methods and digital rectal examination (DRE) is compared to transrectal planimetric prostate ultrasonometry.

Methods

Data were collected from 1,688 population‐based men aged 50–78 years. Measurements included DRE, TRUS using the planimetric method, and three different calliper‐based TRUS methods for the estimation of prostate volume. After 2.1 and 4.2 years these measurements were repeated. The agreement between these methods and the ability to discriminate between prostates with volumes above or below a certain cut‐off was analyzed. The performance of the different methods to measure changes in prostate volume with age was also studied.

Results

All three ultrasound‐based methods showed good discrimination compared to the planimetric method. However, the agreement between planimetric volumetry and the other ultrasound methods and DRE is poor. In this study, 22.6% of the men had a real increase in prostate volume after 4.2 years, using the planimetric technique of transrectal ultrasonometry. Only a small percentage of the men (<1.5%) has a real decrease in prostate volume. The alternative measurement methods had a low predictive value for changes in prostate volume with age as measured with the planimetric method.

Conclusions

Calliper‐based ultrasonometry and DRE show poor agreement with planimetric volume measurement of the prostate. Changes in prostate volume as determined by the planimetric method are poorly detected by the alternative methods. © 2004 Wiley‐Liss, Inc.
Exact evaluation of the location of the optimum torsion axis
Authors: Marino E. M. , Rossi P. P.
Published: August 2004

The paper addresses the issue of the evaluation of a reference axis which in multistorey buildings can play the same role as the elastic centre in one‐storey schemes. In this regard the authors propose an improvement to the procedure previously suggested by Makarios and Anastassiadis for the evaluation of the position of the optimum torsion axis. The above‐mentioned researchers based their evaluation on a parametric analysis of asymmetric frame‐wall systems and thus defined the location of the optimum torsion axis only approximately. The authors, instead, face the problem from an analytical point of view and propose mathematical expressions that rigorously define the position of the same axis. Some examples are finally reported aiming at comparing the two approaches and highlighting the improvements brought by the rigorous approach to the approximate determination of the location of the optimum torsion axis. Copyright © 2004 John Wiley & Sons, Ltd.
Second‐trimester uterine artery Doppler and spontaneous preterm delivery
Authors: Cobian‐Sanchez F. , Prefumo F. , Bhide A. , Thilaganathan B.
Published: August 2004

Objective

To assess the relationship between second‐trimester uterine artery (UtA) Doppler measurements and spontaneous preterm delivery.

Methods

This was a retrospective analysis of UtA Doppler findings at 18–23 weeks' gestation in 234 singleton pregnancies with spontaneous preterm labor and 5472 pregnancies delivered at term. Cases with fetal chromosomal or structural abnormalities, pre‐eclampsia, small‐for‐gestational‐age (SGA) fetuses, concurrent maternal disease, cervical cerclage or history of cone biopsy were excluded.

Results

UtA mean resistance index (RI) and number of protodiastolic notches were not significantly different in the spontaneous preterm labor group compared to the normal group. The 62 preterm deliveries not preceded by spontaneous preterm premature rupture of membranes (PPROM) showed a significantly higher RI and prevalence of bilateral notches than cases of preterm deliveries preceded by PPROM (n = 172). However, this difference was not confirmed in a logistic regression model.

Conclusion

Despite pathological evidence suggesting that defective placentation is associated with spontaneous preterm delivery, second‐trimester UtA resistance, as assessed by Doppler ultrasound investigation, is not different in pregnancies subsequently complicated by preterm labor compared to pregnancies delivered at term. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Ultrasound simulators: experience with the SonoTrainer and comparative review of other training systems
Authors: Maul H. , Scharf A. , Baier P. , Wüstemann M. , Günter H. H. , Gebauer G. , Sohn C.
Published: August 2004

Ultrasound has become indispensable in prenatal diagnosis. Ultrasound training, however, still lacks proper quality assessment and control. Moreover, most fetal anomalies which must be diagnosed during pregnancy are extremely rare. Ultrasound simulators could provide an opportunity to overcome this dilemma. This review summarizes the potential benefits of simulator‐based ultrasound training, briefly describes the properties of a variety of ultrasound simulators that have been developed for various applications including prenatal diagnosis, and presents the SonoTrainer sonography simulation system which makes it possible to run a real‐time simulation of a complete prenatal ultrasound examination. We evaluated the system for the training of first‐ and second‐trimester screening for both normal and pathological findings and found that physicians who received theoretical training and were additionally trained with the simulator (T + S) significantly improved their skills in measurements of nuchal translucency thickness (NT) and crown–rump length (CRL) as compared with colleagues who only underwent theoretical instruction (T) [mean ± SD NT deviation: 0.31 ± 0.1 mm (T + S) vs. 0.62 ± 0.2 mm (T), P < 0.05; mean ± SD CRL deviation: 1.48 ± 2.0 mm (T + S) vs. 3.27 ± 2.5 (T), P < 0.05]. Simulator‐based training enabled physicians to diagnose rare fetal anomalies in the second trimester with a sensitivity of 86% and a specificity of 100%. In a study in which second‐trimester scans including fetal anomalies were presented to physicians, 96% of the participants subjectively estimated their training effect as being good. We therefore conclude that simulator‐based training would provide an ideal educational tool to test, improve and monitor a physician's or technician's ultrasound skills in detecting fetal anomalies. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
On the local and global well-posedness theory for the KP-I equation
Authors: Kenig Carlos E.
Published: August 2004

In this paper we obtain new local and global well-posedness results for the KP-I equation.

Dans cet article nous obtenons de nouveaux résultats sur le caractère bien posé local et global de l'équation KP-I.
New Liouville theorems for linear second order degenerate elliptic equations in divergence form
Authors: Moschini Luisa
Published: August 2004

In this paper we give conditions on the positive function

\varphi ^{2}

under which every bounded solution

σ

of the elliptic equation

\mathrm{∇} \cdot (\varphi ^{2}\mathrm{∇}\sigma ) = 0\text{ in }\mathbb{R}^{n}

must be constant. The case when

\varphi ^{2}

only depends on one or two variables is discussed at length. Moreover the asymptotic behavior of possibly unbounded solutions is characterized, improving in such a way a Liouville theorem due to Berestycki, Caffarelli and Nirenberg.

Dans ce papier nous donnons des conditions sur la fonction positive

\varphi ^{2}

sous lesquelles toute solution de l'équation elliptique

\mathrm{∇} \cdot (\varphi ^{2}\mathrm{∇}\sigma ) = 0\text{ en }\mathbb{R}^{n}

doit être constante. Le cas où

\varphi ^{2}

ne dépend que d'une ou deux variables est analysé en détail. Ensuite, le comportement asymptotique des solutions, éventuellement non bornées est characterisé, en donnant ainsi une généralisation d'un théorème de Liouville dû à Berestycki, Caffarelli et Nirenberg.
Super-critical boundary bubbling in a semilinear Neumann problem
Authors: del Pino Manuel , Musso Monica , Pistoia Angela
Published: August 2004

In this paper we consider the following problem

\tag{0.1}
\begin{cases}
−\mathrm{\Delta }u + u = u^{\frac{N + 2}{N−2} + ɛ}\text{} & \text{in}\:\Omega \text{,} \\ u > 0\text{} & \text{in}\:\Omega \text{,} \\ \frac{\partial u}{\partial \nu } = 0\text{} & \text{on}\:\partial \Omega \text{,} \end{cases}

where

Ω

is a smooth bounded domain in

\mathbb{R}^{N}

and

N⩾3

.

We prove the existence of a one-spike solution to (0.1) which concentrates around a topologically non trivial critical point of the mean curvature of the boundary with positive value. Under some symmetry assumption on

Ω

, namely if

Ω

is even with respect to

N−1

variables and

0 \in \partial \Omega

is a point with positive mean curvature, we prove existence of solutions to (0.1) which resemble the form of a super-position of spikes centered at 0.

Dans cet article nous considérons le problème suivant :

\tag{0.2}
\begin{cases} −\mathrm{\Delta }u + u = u^{\frac{N + 2}{N−2} + ɛ}\text{} & \text{dans}\:\Omega \text{,} \\ u > 0\text{} & \text{dans}\:\Omega \text{,} \\ \frac{\partial u}{\partial \nu } = 0\text{} & \text{sur}\:\partial \Omega \text{,}
\end{cases}

oú

Ω

est un domaine borné régulier dans

\mathbb{R}^{N}

et

N⩾3

. Nous prouvons l'existence d'une solution 1-transitoire au problème (0.2), qui se concentre autour d'un point critique topologiquement non trivial de la courbure moyenne, où celle-ci est strictement positive. Sous certaines hypothéses de symétrie sur

Ω

nous prouvons l'existence de solutions de (0.2) qui ressemblent à une superposition des transitoires centrées en un certain point du bord.
Near‐field scanning optical microscopy in liquid for high resolution single molecule detection on dendritic cells
Authors: Koopman M. , Cambi A. , de Bakker B.I. , Joosten B. , Figdor C.G. , van Hulst N.F. , Garcia-Parajo M.F.
Published: August 2004

Clustering of cell surface receptors into micro‐domains in the plasma membrane is an important mechanism for regulating cellular functions. Unfortunately, these domains are often too small to be resolved with conventional optical microscopy. Near‐field scanning optical microscopy (NSOM) is a relatively new technique that combines ultra high optical resolution, down to 70 nm, with single molecule detection sensitivity. As such, the technique holds great potential for direct visualisation of domains at the cell surface. Yet, NSOM operation under liquid conditions is far from trivial. In this contribution, we show that the performance of NSOM can be extended to measurements in liquid environments using a diving bell concept. For the first time, individual fluorescent molecules on the membrane of cells in solution are imaged with a spatial resolution of 90 nm. Furthermore, using this technique we have been able to directly visualise nanometric sized domains of the C‐type lectin DC‐SIGN on the membrane of dendritic cells, both in air and in liquid.
Non‐enzymatic platelet‐activating factor formation by acetylated proteins
Authors: Thanou Paraskevi G. , Tsoukatos Demokritos C.
Published: August 2004

Substantial amounts of platelet‐activating factor (PAF 1‐O‐alkyl‐2‐acyl‐sn‐glycero‐3‐phosphocholine), the potent phospholipid mediator of allergic and inflammatory reactions, are formed upon incubation of acetylated low‐density lipoprotein, acetylated bovine serum albumin (BSA) and acetylated apolipoprotein A‐I with 1‐0‐hexadecyl‐sn‐glycero‐3‐phosphocholine (lyso‐PAF). Acetylated BSA produced 0.3 nmol PAF/mg of protein after a 6 h incubation period with 40 μM lyso‐PAF. The transfer of acetate bound to acetylated proteins to lyso‐PAF was non‐enzymatic. Chemical PAF formation by acetylated proteins, involved in lipid metabolism and transport, could lead to complication of inflammatory and allergic events.
The conserved carboxy‐terminus of the MscS mechanosensitive channel is not essential but increases stability and activity
Authors: Schumann Ulrike , Edwards Michelle D , Li Chan , Booth Ian R
Published: August 2004

The Escherichia coli MscS mechanosensitive channel protein has a distinct domain structure that terminates in a conserved seven‐strand β barrel. This distinctive feature suggested it could be a critical determinant of channel stability and activity. Measurements on a protein deleted for the base of the vestibule and the β barrel (residues 266–286) suggested that the modified channel had reduced activity. However, induction of the mutant protein resulted in membrane protein accumulation equivalent to wild type and a physiologically functional channel. In patch clamp analysis the activity profile was similar to wild type but reduced numbers of channel were seen per patch, suggesting reduced assembly or stability of the mutant protein. The mutant channel exhibited a subtle change in character – channels did not re‐open after full desensitization. Thus the immediate carboxy‐terminus (residues 266–286) is not essential for MscS gating but improves stability and activity and is required for recovery of channel activity after desensitization.
Environmental history since 11,000 14c yr b.p. of the northeastern Pampas, Argentina, from alluvial sequences of the Luján River
Authors: Prieto Aldo R. , Blasi Adriana M. , De Francesco Claudio G. , Fernández Celina
Published: August 2004

Sedimentological, malacological, and pollen analyses from 14C-dated alluvial sections from the Luján River provide a detailed record of environmental changes during the Holocene in the northeastern Pampas of Argentina. From 11,200 to 9000 14C yr B.P., both sedimentary and biological components suggest that the depositional environment was eutrophic, alkaline, and freshwater to brackish shallow water bodies without significant water circulation. During this time, bioclastic sedimentation was dominant and the shallow water bodies reached maximum development as the climate became more humid, suggesting an increase in precipitation. Short-term fluctuations in climate during the last stage of this interval may have been sufficient to initiate changes in the water bodies, as reduction of the volume alternated with periods of flooding. The beginning of the evolution of shallow swamps in the wide floodplain or huge wetlands was contemporaneous with a sea level lower than the present one. From 9000 and 7000 14C yr B.P., mesotrophic, alkaline, brackish, probably anoxic swamps existed. Between 7000 and 3000 14C yr B.P., anoxic calcareous swamps were formed, with subaerial exposure and development of the Puesto Berrondo Soil (3500–2900 14C yr B.P.). A trend to a reduction of water bodies is recorded from 9000 to ca. 3000 14C yr B.P., with a significant reduction after ca. 7000 14C yr B.P. A shift to subhumid–dry climate after 7000 14C yr B.P. appears to be the main cause. During this time, an additional external forcing toward higher groundwater levels was caused by Holocene marine transgression causing changes in the water bodies levels. The climate became drier during the late Holocene (ca. 3000 yr B.P.), when clastic sedimentation increased, under subhumid–dry conditions. Flood events increased in frequency during this time. From ca. A.D. 1790 to present, the pollen record reflects widespread disturbance of the vegetation during the European settlement.
Men Are Hierarchical, Women Are Egalitarian: An Implicit Gender Stereotype
Authors: Schmid Mast Marianne
Published: August 2004

The goal of the present study was to provide empirical evidence for the existence of an implicit hierarchy gender stereotype indicating that men are more readily associated with hierarchies and women are more readily associated with egalitarian structures. To measure the implicit hierarchy gender stereotype, the Implicit Association Test (IAT, Greenwald et al., 1998) was used. Two samples of undergraduates (Sample 1: 41 females, 22 males; Sample 2: 35 females, 37 males) completed a newly developed paper-based hierarchy-gender IAT. Results showed that there was an implicit hierarchy gender stereotype: the association between male and hierarchical and between female and egalitarian was stronger than the association between female and hierarchical and between male and egalitarian. Additionally, men had a more pronounced implicit hierarchy gender stereotype than women.
Stress and Emotion Recognition: An Internet Experiment Using Stress Induction
Authors: Hänggi Yves
Published: August 2004

Past findings have lead us to assume that the decoding of emotions in facial expression is impaired in stressful situations. The effect of stress on decoding ability is examined through use of an Internet based experiment in which an episode of stress is induced in one group of participants. A fictitious “EQ online evaluation study” serves as a framework. The main task consisted in recognizing 24 emotions from facial expressions in the Ekman-Friesen-series ( Ekman & Friesen, 1976 ), which were presented for approximately 200 ms. Data collected from 86 participants support the underlying hypotheses that stress negatively affects decoding performance. Results are discussed in terms of considerations that must be taken into account due to the method of collecting data in an Internet based study. Ethical aspects of Internet experiments are also discussed.
Parental Closeness and Adolescent Substance Use in single and two-parent Families in Switzerland
Authors: Kuntsche Emmanuel N. , Silbereisen Rainer K.
Published: August 2004

This study investigates whether family structure and parental closeness are associated with adolescent substance use and whether the association between parental closeness and adolescent substance use differs by family structure. A national representative sample of 1488 9th graders (mean age 15.8 years; SD = 0.52) was analyzed separately by gender using t-tests and a multiple group comparison in linear equation models. Adolescents from single-parent families showed a higher level of substance use compared to those living with both parents. The results also confirm the protective effect of parental closeness on adolescent substance use, though this was more effective for girls in single-parent families but less effective for boys. Therefore, boys from single-parent families in particular should be targeted by prevention programs.
Mütterliches Rauchen in der Schwangerschaft: Risikofaktor für eine ADHS des Kindes?
Authors: Laucht Manfred , H. Schmidt Martin
Published: August 2004

Zusammenfassung: Fragestellung: Der Zusammenhang des mütterlichen Rauchens in der Schwangerschaft mit Verhaltensproblemen des Kindes soll auf seine Spezifität überprüft werden. Methode: In einer prospektiven Längsschnittstudie an einer Geburtskohorte von 362 Risikokindern wurden der elterliche Tabakkonsum, Kennwerte der kognitiven und sozial-emotionalen Entwicklung des Kindes sowie Merkmale der familiären Umwelt erhoben. Ergebnisse: Etwa ein Viertel der Mütter berichtete über einen regelmäßigen Tabakkonsum in der Schwangerschaft. Kinder dieser Gruppe zeigten eine deutlich erhöhte ADHS-Rate. Dieser Zusammenhang blieb auch nach Kontrolle kovariierender Faktoren bestehen. Schlussfolgerungen: Rauchen in der Schwangerschaft kann als unabhängiger Risikofaktor für eine ADHS des Kindes angesehen werden.
Neurofeedback in der Behandlung der Aufmerksamkeitsdefizit-Hyperaktivitätsstörung (ADHS) im Kindes- und Jugendalter
Authors: Holtmann Martin , Stadler Christina , Leins Ulrike , Strehl Ute , Birbaumer Niels , Poustka Fritz
Published: August 2004

Zusammenfassung: Einleitung: In der Therapie der Aufmerksamkeitsdefizit-Hyperaktivitätsstörung (ADHS) sind viele nicht-medikamentöse Behandlungsmethoden den Nachweis ihrer Wirksamkeit schuldig geblieben. Für das Neurofeedback (auch EEG-Biofeedback) hat sich die Evidenzbasis in den vergangenen Jahren verbessert. Neurofeedback bewirkt abhängig vom Trainings-Protokoll Veränderungen des EEG-Frequenzspektrums oder der ereigniskorrelierten Potentiale bei ADHS und strebt über die gelernte Modifikation dieser Parameter eine Verbesserung der ADHS-Kernsymptome an. Methoden: In dieser Übersichtsarbeit werden die vorliegenden Forschungsbefunde detailliert dargelegt. Ergebnisse: Die durch das Neurofeedback erreichten kurzfristigen Verbesserungen entsprachen in drei kontrollierten Studien denen einer pharmakotherapeutischen Stimulanzien-Behandlung. Neurofeedback führte zu einer signifikanten Reduktion von Unaufmerksamkeit, Impulsivität und Hyperaktivität. Darüber hinaus fand sich eine anhaltende Normalisierung des Spontan-EEGs, während eine Stimulanzientherapie keine vergleichbare Normalisierung bewirkte; es traten keine unerwünschten Wirkungen auf. Untersuchungen zur Wirkdauer der Neurofeedback-Effekte sind ermutigend, stützen sich aber auf kleine Patientenzahlen. Schlussfolgerung: Neurofeedback ist ein viel versprechender Ansatz in der Behandlung aufmerksamkeitsgestörter, hyperaktiver Kinder. Gleichwohl besteht Bedarf an weiteren kontrollierten Studien mit einheitlichen diagnostischen Kriterien, ausreichend großen Stichproben, geeigneten Veränderungsmaßen und Katamnese-Untersuchungen.
Komplexe Halluzinationen im Migräneanfall bei 10-jährigem Patienten - eine Fallbeschreibung und Übersichtsarbeit
Authors: Romanos Marcel
Published: August 2004

Zusammenfassung: Fragestellung: Die Migräne ist bei Kindern mit einer Prävalenz von drei bis zehn Prozent eine häufige Erkrankung. Visuelle Auren sind als Charakteristikum der klassischen Migräne in der Literatur ausgiebig beschrieben. Vornehmlich handelt es sich um primäre Halluzinationen, Beschreibungen komplexer Halluzinationen hingegen sind kaum zu finden. Die vorliegende kasuistische Darstellung beinhaltet nach unserem Wissen das jüngste beschriebene Alter von komplexen Halluzinationen während einer Migräneattacke. Mögliche pathophysiologische Mechanismen und differentialdiagnostische Überlegungen werden auf Grundlage der bestehenden Literatur diskutiert. Methode: Dargelegt wird die Kasuistik eines 10-jährigen Patienten, welcher von einer komplexen visuellen Halluzination bei einer Migräneattacke berichtet. Es werden Symptomatik, Vorgeschichte sowie diagnostische Schritte dargestellt. Differentialdiagnostisch zu einer migränösen Aura werden das «Alice-in-Wonderland-Syndrom», «Liliputanische Halluzinationen», die Basilarmigräne sowie eine epileptische Genese diskutiert. Schlussfolgerung: Für komplexe Halluzinationen bei Migräne ist vermutlich ein analoger Pathomechanismus zu den primären Halluzinationen der migränösen Aura anzunehmen, so dass durch die vorliegende Arbeit die große Variabilität der migränösen Aura erneut unterstrichen wird.
The complex life of simple sphingolipids
Authors: Futerman Anthony H , Hannun Yusuf A
Published: August 2004

The extensive diversity of membrane lipids is rarely appreciated by cell and molecular biologists. Although most researchers are familiar with the three main classes of lipids in animal cell membranes, few realize the enormous combinatorial structural diversity that exists within each lipid class, a diversity that enables functional specialization of lipids. In this brief review, we focus on one class of membrane lipids, the sphingolipids, which until not long ago were thought by many to be little more than structural components of biological membranes. Recent studies have placed sphingolipids—including ceramide, sphingosine and sphingosine‐1‐phosphate—at the centre of a number of important biological processes, specifically in signal transduction pathways, in which their levels change in a highly regulated temporal and spatial manner. We outline exciting progress in the biochemistry and cell biology of sphingolipids and focus on their functional diversity. This should set the conceptual and experimental framework that will eventually lead to a fully integrated and comprehensive model of the functions of specific sphingolipids in regulating defined aspects of cell physiology.
ATM and ataxia telangiectasia
Authors: McKinnon Peter J
Published: August 2004

Ataxia telangiectasia (AT) has long intrigued the biomedical research community owing to the spectrum of defects that are characteristic of the disease, including neurodegeneration, immune dysfunction, radiosensitivity and cancer predisposition. Following the identification of mutations in ATM (ataxia telangiectasia, mutated) as the underlying cause of the disease, biochemical analysis of this protein kinase has shown that it is a crucial nexus for the cellular response to DNA double‐stranded breaks. Many ATM kinase substrates are important players in the cellular responses that prevent cancer. Accordingly, AT is a disease that results from defects in the response to specific types of DNA damage. Thus, although it is a rare neurodegenerative disease, understanding the biology of AT will lead to a greater understanding of the fundamental processes that underpin cancer and neurodegeneration.
Contact phenomena in nanowire arrays
Authors: Ruda H. E. , Shik A.
Published: August 2004

The capacitance–voltage characteristic C(V) of an array of semiconductor nanowires perpendicular to a bulk metallic electrode is considered theoretically. For sufficiently high doping ν0 of nanowires, C(V) is shown to differ dramatically from that of a bulk sample having a strong maximum in the depletion branch. The position of the maximum is proportional to ν0 and can be used for its determination.
Improvement of signal-to-noise ratio of a subterahertz spectrometer using a continuous-wave multimode laser diode by single-mode fiber optics
Authors: Morikawa O. , Fujita M. , Hangyo M.
Published: August 2004

The signal-to-noise ratio of the subterahertz spectroscopic system proposed previously, which uses a continuous-wave multimode laser diode and photoconductive antennas, is improved significantly by adopting single-mode fiber optics. The noise estimated from the transmittance measurement of a Si wafer is reduced to about 1∕6 of that obtained by the previous system. The improvement is based on the reduction of the random phase distribution of laser modes with various mode patterns, resulting in the increase of the continuous components in the spectrum.
Ultrafast optical emission of nanodiamond induced by laser excitation
Authors: Zhao F. L. , Gong Z. , Liang S. D. , Xu N. S. , Deng S. Z. , Chen J. , Wang H. Z.
Published: August 2004

The ultrafast optical emission of nanosized (∼5nm) crystallites has been detected under the picosecond (ps) laser excitation of 300nm through ultrafast fluorescence spectroscopy. This optical emission, photoluminescence (PL), induced at a laser wavelength of 300nm confines blue light. The ultrafast PL spectrum deconvoluted by a Monte Carlo method shows that two fast emission processes with decaytimes of 60 and 350ps. This type of ultrafast emission has not been observed under the same experimental conditions from the samples of a natural single crystal and an impure natural single crystal diamond. The mechanism responsible for this visible ultrafast emission is proposed by taking into account the effect of surface states and large surface-to-volume ratio of nanoparticles. All of these findings demonstrate the feasibility of using large band-gap nanomaterials to generate ultrafast optical emission at various wavelengths.
Pumping intensity dependent surface charge accumulation and redshifted microphotoluminescence of silicon-implanted quartz
Authors: Lin Gong-Ru , Yu Kuo-Cheng , Lin Chun-Jung , Kuo Hao-Chung , Ou-Yang Miao-Chia
Published: August 2004

The pumping-intensity dependency of nanocrystallite silicon (nc-Si) related microphotoluminescence (μ-PL) from multirecipe Si-implanted quartz is characterized. After annealing at 1100°C for 3h, theμ-PL at 724nm contributed by nc-Si with a diameter of about 4nm is maximized. By increasing the pumping intensity from 10kW∕cm2 to 300kW∕cm2, the μ-PLs of 1 and 3-h-annealed Si-implanted quartz samples are redshifted by <1.2 and 11nm, respectively. The μ-PL of 3-h-annealed sample further redshifts by 2.5nm after pumping at 300kW∕cm2 for h. Such a redshift in PL is attributed to the anomalous quantum Stark effect under strong illumination, which photoionizes the buried nc-Si and initiates an electric field beneath the surface of Si-implanted quartz. The measurement of accumulating charges and voltage drop during illumination primarily elucidate the correlation between redshift in PL and the photoionized nc-Si induced surface electric field.
Tuning In0.3Ga0.7As∕GaAs multiple quantum dots for long-wavelength infrared detectors
Authors: Chua Ying Chao , Decuir E. A. , Passmore B. S. , Sharif K. H. , Manasreh M. O. , Wang Z. M. , Salamo G. J.
Published: August 2004

Optical absorption spectra of intersubband transitions in In0.3Ga0.7As∕GaAs multiple quantum dots were investigated using the optical absorption as a function of the number of In0.3Ga0.7As monolayers deposited using the molecular-beam epitaxy Stranski–Krastanow technique. The peak position energy reached 13.7μm for a sample containing 50 monolayers of In0.3Ga0.7As. The lack of the observation of intersubband transitions in small quantum dots, where the number of the deposited monolayer is less than 15 monolayers, is an indication of the absence of quantum confinement. On the other hand, the presence of high dislocations density in larger quantum dots, where the deposited number of monolayers exceeds 50, could be the reason of why the intersubband transitions are degraded.
Noncontact scanning impedance imaging in an aqueous solution
Authors: Hawkins Aaron R. , Liu Hongze , Oliphant Travis E. , Schultz Stephen M.
Published: August 2004

We present a method for imaging based on noncontact electrical impedance measurements and mechanical scanning. Measurement results are shown for an initial system based on this concept. An impedance probe design is presented, applicable to the test system. Line-scan data plots of high impedance contrast structures show a good fit to a theoretical physical model. Image resolutions on the order of 100μm are indicated for the initial system. Two-dimensional impedance images of biological tissue generated by this technique are shown.
Polymer coating on the surface of zirconia nanoparticles by inductively coupled plasma polymerization
Authors: He Wei , Guo Zhigang , Pu Yikang , Yan Luting , Si Wenjie
Published: August 2004

Polymer coating on the surface of inorganic ceramic nanoparticles is beneficial to decrease agglomeration and improve dispersion in organic solvent in ceramic injection moulding technology. A layer of thin polymer film on zirconia nanoparticles is deposited by inductively coupled ethylene/nitrogen plasma. Transmission electron microscopy photographs indicate the presence of uniform polymer coatings and the thickness of the polymer layer is estimated as several nanometers. The chemical structure of the film is revealed as quasi-polyethylene long hydrocarbon chain by x-ray photoelectron spectroscopy examination.
Hot hole excitation of EuGa2S4 electroluminescent thin films
Authors: Tanaka Katsu , Okamoto Shinji
Published: August 2004

This letter describes which carrier type (electrons or holes) is dominant for EuGa2S4 thin film electroluminescent (TFEL) excitation. The transient EL wave form was measured on the EuGa2S4 TFEL devices having a single insulating thin film, which emit pure green EL due to the 5d–4f transition of Eu2+ ions. An asymmetric EL wave form was observed under a rectangular applied voltage. The EL occurs at the positively biased side of the EuGa2S4 thin film. This indicates that the green EL occurs because of hot hole excitation. Hot electrons are known to be dominant carriers to excite the luminescent centers in TFEL devices. Hot holes are also effective carriers for TFEL excitation.
Ultratough nanocrystalline copper with a narrow grain size distribution
Authors: Youssef Khaled M. , Scattergood Ronald O. , Linga Murty K. , Koch Carl C.
Published: August 2004

We report a unique way of using mechanical milling/in situ consolidation at both liquid-nitrogen and room temperature to produce artifact-free nanocrystalline Cu(23nm) with a narrow grain size distribution. This nanocrystalline Cu exhibits an extraordinarily high yield strength (770MPa), as predicted from a Hall–Petch extrapolation, along with good ductility (comparable with ∼30% uniform tensile elongation). Possible factors leading to this excellent optimization of strength and ductility are discussed.
Spin-dependent quantum transport in periodic magnetic modulations: Aharonov–Bohm ring structure as a spin filter
Authors: Wu M. W. , Zhou J. , Shi Q. W.
Published: August 2004

Quantum interference in Aharonov–Bohm (AB) ring structure provides additional control of spin at mesoscopic scale. We propose a scheme for spin filter by studying the coherent transport through the AB structure with lateral magnetic modulation on both arms of ring structure. Large spin polarized current can be obtained with many energy channels.
Defect-enhanced photoconductive response of silicon-implanted borosilicate glass
Authors: Lin Gong-Ru , Lin Chun-Jung , Lin Chi-Kuan
Published: August 2004

The E′δ-defect-enhanced photoconductivity of a metal–semiconductor–metal photodetector (MSM-PD) made on Si-implanted borosilicate glass (BSO:Si+) substrate is reported. The dark current of as-implanted BSO:Si+ MSM-PD is only 0.1nA at bias of 70V. The photocurrent of as-implanted BSO:Si+ MSM-PD illuminated at 488nm is 0.91nA, corresponding to photoconductive gain of 9.1dB. The E′δ-defects luminescent at 520nm are activated after 2h annealing, which enhances the photocurrent of BSO:Si+ MSM-PD by one order of magnitude. Optimized responsivity, noise equivalent power, and detectivity of BSO:Si+ MSM-PD are 4.0μA∕W, 1.2×10−9W∕Hz1∕2, and 3.5×105cmHz1∕2∕W, respectively. The electron paramagnetic resonance and etching-dependent photocurrent analysis corroborate the E′δ-defect-related photoconductivity of the BSO:Si+ glass.
Relaxorlike dielectric properties and history-dependent effects in the lead-free K0.5Na0.5NbO3–SrTiO3 ceramic system
Authors: Bobnar V. , Bernard J. , Kosec M.
Published: August 2004

Typical relaxorlike dielectric properties, such as broad dispersive dielectric maximum, Vogel–Fulcher temperature dependence of the characteristic relaxation frequency, and paraelectric-to-glass crossover in the temperature dependence of the dielectric nonlinearity, have been detected in the derived lead-free K0.5Na0.5NbO3–SrTiO3 ceramic system. Relatively large values of the dielectric constant, being almost independent of the frequency in the range of 100Hz–1MHz, suggest possible applications based on this environmentally friendly system. Furthermore, the history-dependent effects, such as aging of the dielectric constant and fatigue of the polarization switching, are much weaker than in some widely used lead-based relaxors.
Powder second-harmonic generation study of (K2O)15(Nb2O5)15(TeO2)70 glass ceramic
Authors: Hart Robert T. , Ok Kang Min , Halasyamani P. Shiv , Zwanziger Josef W.
Published: August 2004

A power second-harmonic generation (SHG) study has been carried out on (K2O)15(Nb2O5)15(TeO2)70 glass ceramic, which consists of centrosymmetric crystals embedded in a centrosymmetric glass matrix. The effective second-order nonlinear optical coefficient, χ(2), of this material at 532nm is found to be 1.3pm∕V or approximately ten times that of quartz, leading to a maximum second-harmonic intensity approximately 100 times that of quartz. This material is nonphase matchable, with a coherence length of 30μm. We conclude that the SHG in this material originates from the abrupt changes in optical susceptibility at the interfaces between the glass and crystal, together with the higher-order nonlinear response.