julilili42/papers huggingface dataset:
Proven-prompt vector normalizer
2002-12-30

The cosine of the angle between two vectors is a frequency needed quantity in computer graphics algorithms. Provided the vectors are normalized, it can easily be computed by evaluating their dot product. However, this requires the essential problem of rapidly normalizing a vector, which includes three divisions and one square root operation, to be solved. The authors describe a single-chip VLSI implementation of a pipelined vector normalizer and give design details of a fast and compact square root unit.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>
Using electronic facsimiles of documents for automatic reconstruction of underlying hypertext structures
2002-12-30

When looking for detailed pieces of information within the facsimiles of documents, a user has only a highly limited set of supportive tools at his disposal. As a solution to this problem, the use of automatically generated hypertext structures is proposed. These structures also include conventional mechanisms like table of contents, index, or full text search, but extend to the possibility of associative searches. The automatic generation of hypertext structures is based on two sources of information: the output of a commercial OCR system and a document type dependent specification file including the specifications for both structure elements and link types. Thus, additional information hidden in layout and typography is taken into account in addition to the plain ASCII representation of the document. The browsing problems that may arise from a hypertext's nonlinearity do not appear, because the user also has access to the document in its original linear fashion.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>
Nanoelectronic devices: opportunities and challenges
2002-12-30

Summary form only given, as follows. Progress in scaling of semiconductor devices has enabled the exponential growth in complexity and functionality of integrated circuits over the past decades. Limits to this development originating from device physics, circuit architecture, but also from materials, processes and possibly economics become apparent. The work on confined electron systems conducted over the past ten years exhibiting quantum interference, quantum size, quantum resonant tunneling and Coulomb blockade effects may well lead to new ways to further increase integrated circuit functionality, if appropriate architectures and solutions to the fabrication problems can be found. Novel switching effects based on motion of single atoms in tunneling configurations, molecular conduction and arrangements possibly combined with self assembly and biological materials represent even more potential alternatives. The paper will discuss key issues associated with different approaches.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>
Parameterized evaluation of macromolecules and lipids in proton MR spectroscopy of brain diseases
2002-12-31

Abstract Short echo time (TE) proton MR spectra of the brain include signals of several metabolites as well as macromolecules. In various pathologies, such as brain tumors and multiple sclerosis (MS), the presence of mobile lipids or pathologically altered macromolecules may provide useful additional diagnostic information. A reliable quantitation of these resonances, however, is often not possible due to the lack of adequate prior knowledge. Furthermore, even if advanced fitting procedures are used, a reliable evaluation of metabolites in the presence of pathological lipids or macromolecules often fails if the latter are omitted in the spectral evaluation. In this study, a method is presented for the simultaneous evaluation of all visible components, including metabolites, lipids, and macromolecules, by the use of the fitting procedure LCModel. A standard basis set of brain metabolites was extended by inclusion of parameterized components for macromolecules and lipids that were derived from metabolite‐nulled in vivo spectra of normal brain and high‐grade gliomas, respectively. The improved spectral quantitation is demonstrated in glial brain tumors and MS lesions as well as in normal brain. It is pointed out that both macromolecules and lipids must be included to provide a proper spectral evaluation. Magn Reson Med 49:19–28, 2003. © 2003 Wiley‐Liss, Inc.
Comparison of quantitative shear wave MR‐elastography with mechanical compression tests
2002-12-31

Abstract The mechanical properties of in vivo soft tissue are generally determined by palpation, ultrasound measurements (US), and magnetic resonance elastography (MRE). While it has been shown that US and MRE are capable of quantitatively measuring soft tissue elasticity, there is still some uncertainty about the reliability of quantitative MRE measurements. For this reason it was decided to determine in vitro how MRE measurements correspond with other quantitative methods of measuring characteristic elasticity values. This article presents the results of experiments with tissue‐like agar–agar gel phantoms in which the wavelength of strain waves was measured by shear wave MR elastography and the resultant shear modulus was compared with results from mechanical compression tests with small gel specimens. The shear moduli of nine homogeneous gels with various agar–agar concentrations were investigated. The elasticity range of the gels covered the elasticity range of typical soft tissues. The systematic comparison between shear wave MRE and compression tests showed good agreement between the two measurement techniques. Magn Reson Med 49:71–77, 2003. © 2003 Wiley‐Liss, Inc.
ARAMEMNON, a Novel Database for Arabidopsis Integral Membrane Proteins
2003-01-01

Abstract A specialized database (DB) for Arabidopsis membrane proteins, ARAMEMNON, was designed that facilitates the interpretation of gene and protein sequence data by integrating features that are presently only available from individual sources. Using several publicly available prediction programs, putative integral membrane proteins were identified among the approximately 25,500 proteins in the Arabidopsis genome DBs. By averaging the predictions from seven programs, approximately 6,500 proteins were classified as transmembrane (TM) candidate proteins. Some 1,800 of these contain at least four TM spans and are possibly linked to transport functions. The ARAMEMNON DB enables direct comparison of the predictions of seven different TM span computation programs and the predictions of subcellular localization by eight signal peptide recognition programs. A special function displays the proteins related to the query and dynamically generates a protein family structure. As a first set of proteins from other organisms, all of the approximately 700 putative membrane proteins were extracted from the genome of the cyanobacterium Synechocystis sp. and incorporated in the ARAMEMNON DB. The ARAMEMNON DB is accessible at the URL http://aramemnon.botanik.uni-koeln.de.
Phloem loading and unloading of sugars and amino acids
2003-01-01

ABSTRACT In terrestrial higher plants, phloem transport delivers most nutrients required for growth and storage processes. Some 90% of plant biomass, transported as sugars and amino nitrogen (N) compounds in a bulk flow of solution, is propelled though the phloem by osmotically generated hydrostatic pressure differences between source (net nutrient export) and sink (net nutrient import) ends of phloem paths. Source loading and sink unloading of sugars, amino N compounds and potassium largely account for phloem sap osmotic concentrations and hence pressure differences. A symplasmic component is characteristic of most loading and unloading pathways which, in some circumstances, may be interrupted by an apoplasmic step. Raffinose series sugars appear to be loaded symplasmically. However, sucrose, and probably certain amino acids, are loaded into minor veins from source leaf apoplasms by proton symporters localized to plasma membranes of their sieve element/companion cell (se/cc) complexes. Sucrose transporters, with complementary kinetic properties, are conceived to function as membrane transporter complexes that respond to alterations in source/sink balance. In contrast, symplasmic unloading is common for many sink types. Intervention of an apoplasmic step, distal from importing phloem, is reserved for special situations. Effluxers that release sucrose and amino acids to the surrounding apoplasm in phloem loading and unloading are yet to be cloned. The physiological behaviour of effluxers is consistent with facilitated membrane transport that can be energy coupled. Roles of sucrose and amino acid transporters in phloem unloading remain to be discovered along with mechanisms regulating symplasmic transport. The latter is hypothesized to exert significant control over phloem unloading and, in some circumstances, phloem loading.
Temporary Inactivation of the Bed Nucleus of the Stria Terminalis But Not of the Amygdala Blocks Freezing Induced by Trimethylthiazoline, a Component of Fox Feces
2003-01-01

Presentation of trimethylthiazoline (TMT, a component of fox feces) to laboratory rats elicits freezing, a prominent behavioral sign of anxiety or fear. The present study investigated the neural basis of this unlearned response. Muscimol, a GABA(A) receptor agonist, was injected (4.4 nmol/0.5 microl) into the bed nucleus of the stria terminalis (BNST) as well as into the amygdala, two brain areas known to be involved in anxiety and fear. Temporary inactivation of the BNST but not of the amygdala significantly blocked TMT-induced freezing. This effect was not caused by an enhancement of motor activity after BNST inactivation. In addition, these results confirm previous studies showing that freezing is possible despite amygdala inactivation. These results, and other findings in the literature, suggest that the BNST is critically involved in unlearned fear, whereas the amygdala is more involved in the acquisition and expression of learned fear.
Dependence of <i>Plasmodium falciparum In Vitro</i> Growth on the Cation Permeability of the Human Host Erythrocyte
2003-01-01

Intraerythrocyte growth of the malaria parasite Plasmodium falciparum induces a Ca2+-permeable unselective cation conductance in the host cell membrane which is inhibited by ethylisopropylamiloride (EIPA) and is paralleled by an exchange of K+ by Na+ in the host cytosol. The present study has been performed to elucidate the functional significance of the electrolyte exchange. Whole-cell patch-clamp experiments confirmed the Ca2+ permeability and EIPA sensitivity of the Plasmodium falciparum induced cation channel. In further experiments, ring stage-synchronized parasites were grown in vitro for 48 h in different test media. Percentage of Plasmodium-infected and phosphatidylserine-exposing erythrocytes was measured with FACS analysis by staining with the DNA-dye Syto16 and annexin V, respectively. The increase of infected cells was not significantly affected by an 8 h replacement of NaCl in the culture medium with Na-gluconate but was significantly blunted by replacement of NaCl with KCl, NMDG-Cl or raffinose. Half maximal growth was observed at about 25 mM Na+. The increase of infected cells was further inhibited by EIPA (IC50< 10 microM) and at low extracellular free Ca2+. Infected cells displayed significantly stronger annexin binding, an effect mimicked by exposure of noninfected erythrocytes to oxidative stress (1 mM T-butylhydroperoxide for 15 min) or to Ca2+ ionophore ionomycin (1 microM for 60 min). The observations indicate that parasite growth requires the entry of both, Na+ and Ca2+ cations into the host erythrocyte probably through the EIPA sensitive cation channel. Ca2+ entry further induces break-down of the phospholipid asymmetry in the host membrane.
Reduced amino acid content in transgenic potato tubers due to antisense inhibition of the leaf H+/amino acid symporter StAAP1
2003-01-01

Summary Transport processes across the plasma membrane of leaf vascular tissue are essential for transport and distribution of assimilates. In potato, leaves are the predominant sites for nitrate reduction and amino acid biosynthesis. From there, assimilated amino acids are exported through the phloem to supply tubers with organic nitrogen. To study the role of amino acid transporters in long‐distance transport and allocation of organic nitrogen in potato plants, a gene encoding a functional, leaf‐expressed amino acid permease StAAP1 was isolated. Similar to the sucrose transporter SUT1, StAAP1 expression was induced during the sink‐to‐source transition, indicating a role in phloem loading. To test the role of StAAP1, expression was inhibited by an antisense approach. Transgenic plants with reduced StAAP1 expression were phenotypically indistinguishable from wild type, as were photosynthetic capacity and tuber yield. However, tubers from antisense StAAP1 plants showed up to 50% reduction in free amino acid contents. In comparison, starch content was not affected or tended to increase relative to wild type. The reduction in all amino acids except aspartate in the antisense plants is consistent with the properties of amino acid permeases (AAPs) found in heterologous systems. The results demonstrate an important role for StAAP1 in long‐distance transport of amino acids and highlight the importance of plasma membrane transport for nutrient distribution in plants.
Some notes on phonological phrasing in Brazilian Portuguese
2003-01-01

In this paper, we argue that phonological phrasing in Brazilian Portuguese is determined by the interaction of right-alignment of syntactic and phonological phrases (Selkirk 1986) and a eurythmic factor of Uniformity (Ghini 1993), which prefers p-phrases of equal prosodic length. The Uniformity requirement shows some unexpected properties. It is not tied to a preferred length of p-phrases, and it appears to be restricted to p-phrases overlapping with the subject and the verb of the clause.
Goal Configurations and Processing Strategies as Moderators Between Instructional Design and Cognitive Load: Evidence From Hypertext-Based Instruction
2003-01-01

This is an electronic version of the article published in: Gerjets, P. & Scheiter, K. (2003). Goal configurations and processing strategies as moderators between instructional design and cognitive load: Evidence from hypertext-based instruction. Educational Psychologist, 38 (1), 33-41 © 2000 Taylor & Francis, available online at: http://www.informaworld.com/smpp/content?content=10.1207/S15326985EP3801_5
The Sucrose TransporterStSUT1Localizes to Sieve Elements in Potato Tuber Phloem and Influences Tuber Physiology and Development,
2003-01-01

Abstract The sucrose (Suc) H+-cotransporterStSUT1 from potato (Solanum tuberosum), which is essential for long-distance transport of Suc and assumed to play a role in phloem loading in mature leaves, was found to be expressed in sink tubers. To answer the question of whether SUT1 serves a function in phloem unloading in tubers, the promoter was fused to gusA and expression was analyzed in transgenic potato. SUT1 expression was unexpectedly detected not in tuber parenchyma but in the phloem of sink tubers. Immunolocalization demonstrated that StSUT1 protein was present only in sieve elements of sink tubers, cells normally involved in export of Suc from the phloem to supply developing tubers, raising the question of the role of SUT1 in tubers. SUT1 expression was inhibited by antisense in transgenic potato plants using a class I patatin promoter B33, which is primarily expressed in the phloem of developing tubers. ReducedSUT1 expression in tubers did not affect aboveground organs but led to reduced fresh weight accumulation during early stages of tuber development, indicating that in this phase SUT1 plays an important role for sugar transport. Changes in Suc- and starch-modifying enzyme activities and metabolite profiles are consistent with the developmental switch in unloading mechanisms. Altogether, the findings may suggest a role of SUT1 in retrieval of Suc from the apoplasm, thereby regulating the osmotic potential in the extracellular space, or a direct role in phloem unloading acting as a phloem exporter transferring Suc from the sieve elements into the apoplasm.
Electrophysiological Properties of the <i>Plasmodium falciparum</i>-Induced Cation Conductance of Human Erythrocytes
2003-01-01

Intraerythrocyte survival of the malaria pathogen Plasmodium Falciparum depends on the induction of the new-permeability-pathways (NPPs) in the host cell membrane. NPPs are characterized as anion- and organic osmolyte-permeable channels which also exhibit a low but significant permeability for inorganic cations. To disclose the electrophyiologial properties of this infection-induced cation permeability whole-cell currents were recorded in Plasmodium Falciparum-infected human erythrocytes (pRBC) using bath and pipette solutions with low Cl(-) concentrations. The data disclose a nonselective cation conductance (G(CAT)) which activated upon removal of extracellular Cl(-). Upon activation, G(CAT) was 0.3 +/- 0.05 nS (n=16) in control RBC and 2.0 +/- 0.3 nS (n = 32) in pRBC indicating an induction of G(CAT) during the infection. G(CAT) of pRBC exibited a relative permselectivity for monovalent cations of Cs(+)ñK(+)>Na(+)>Li(+) (P(Na)/P(K) ñ 0.5) with a significant permeability for Ca(2+). G(CAT) of pRBC was inhibited by NPPs blockers (furosemide and NPPB) and cation channel blockers (amiloride, EIPA, GdCl(3)) with the highest sensitivity to EIPA (IC(50)-0.5 microM). Most importantly, the blocker sensitivities differed between the infection-induced anion conductances and G(CAT) suggesting that G(CAT) and the anion conductances represent different channel proteins which in concert build up the NPPs.
Hierarchical Techniques in Collision Detection for Cloth Animation
2003-01-01

In the animation of deformable objects, collision detection is crucial for the performance. Contrary to volumetric\\nbodies, the accuracy requirements for the collision treatment of textiles are particularly strict because any overlapping\\nis visible. Therefore, we apply methods speci cally designed for deformable surfaces that speed up the\\ncollision detection. In this paper the ef ciency of bounding volume hierarchies is improved by adapted techniques\\nfor building and traversing these hierarchies. An extended set of heuristics is described that allows pruning of the\\nhierarchy. Oriented inflation of bounding volumes enables us to detect proximities with a minimum of extra cost.
On Magnus Integrators for Time-Dependent Schrödinger Equations
2003-01-01

Numerical methods based on the Magnus expansion are an efficient class of integrators for Schrödinger equations with time-dependent Hamiltonian. Though their derivation assumes an unreasonably small time step size, as would be required for a standard explicit integrator, the methods perform well even for much larger step sizes. This favorable behavior is explained, and optimal-order error bounds are derived that require no or only mild restrictions of the step size. In contrast to standard integrators, the error does not depend on higher time derivatives of the solution, which is in general highly oscillatory.
Treatment with the selective muscarinic ml agonist talsaclidine decreases cerebrospinal fluid levels of Aβ42in patients with Alzheimer's disease
2003-01-01

The amyloid beta-peptides A beta 40 and A beta 42 are highly amyloidogenic constituents of brain beta-amyloid plaques in Alzheimer's disease (AD). Lowering their formation may be achieved by modulating the activities of proteases that cleave the amyloid precursor protein (A beta PP), including alpha- beta-, and gamma-secretases. Talsaclidine is a functionally selective muscarinic m1 agonist that stimulates non-amyloidogenic alpha-secretase processing in vitro. We compared cerebrospinal fluid (CSF) levels of A beta 40 and A beta 42 measured by ELISA before and at the end of 4 weeks of treatment with talsaclidine. The medication was administered in a double-blind, placebo-controlled, and randomized clinical study to 40 patients with AD. Talsaclidine (n = 34) decreased CSF levels of A beta 42 by a median of 19% (p < 0.001) as compared to baseline. The mean difference between CSF levels of A beta 42 before and after treatment with talsaclidine (n = 34) was -46 +/- 73 (SD) pg/ml as compared to 0 +/- 8 (SD) pg/ml with placebo (n = 6) (p < 0.05). CSF levels of A beta 40 increased during treatment with placebo (n = 6) while they remained stable during treatment with talsaclidine (n = 31) (1.118 +/- 1.710 ng/ml, and -0.170 +/- 0.967 ng/ml, respectively; p < 0.05). These data show that treatment with the m1 agonist talsaclidine reduced A beta peptides, and particularly A beta 42, in AD patients, suggesting it as a potential amyloid lowering therapy of AD.
Time, Space and Hippocampal Functions
2003-01-01

The hippocampus is one of the most researched structures of the brain. Studies of lesions in humans, primates and rodents have suggested to some that the primary role of the hippocampus is to act as a temporary memory buffer which is required for the consolidation of long-term memory. The famous case study of patient H.M., in particular, seemed to suggest that the hippocampus was of crucial importance for memory formation. However, recordings of single neurons in freely moving rodents did not support this notion. In such recordings, neurons were found that were active predominately when the animal passed through a particular area in space. Consequently, these neurons were termed 'place cells' and a theory was developed that suggested that the hippocampus acts as a 'cognitive map' that is required for spatial orientation. It was then found that H.M. had significant damage to his temporal lobes that included the amygdala, rhinal cortices, and other areas. Further case studies and selective hippocampal lesions in primates resulted in much milder amnestic symptoms, and lesions of defined cortical areas in the temporal lobes showed that a number of functions previously attributed to the hippocampus were in fact linked to these areas. Further analysis of neuronal activity in the hippocampus showed that not only is spatial information represented there, but also additional information, such as speed of movement, direction of movement, match or non-match detection, olfactorial identification, and others. In addition, it was found that selective lesions of the hippocampus in rodents impaired spatial navigation and memory formation only mildly. Only simultaneous lesions of several cortical areas in conjunction with the hippocamus could reproduce the impairments and symptoms that were previously thought to be observed after hippocampal lesions alone. In conclusion it is proposed that information processing and memory formation is shared by several brain areas that act as a functional system. This review presents evidence from many different studies that the hippocampus is part of this system and plays a supportive role in associating complex multimodal information and laying down new memory traces. In addition, the concept of allocating specific functions (such as the development of a cognitive map) exclusively to the hippocampus is rejected.
Pyrocoll, an Antibiotic, Antiparasitic and Antitumor Compound Produced by a Novel Alkaliphilic Streptomyces Strain
2003-01-01

A new secondary metabolite was detected in the culture extract of Streptomyces sp. AK 409 by HPLC-diode-array screening. The metabolite was identified as pyrocoll, which is known to be a constituent of cigarette smoke. Pyrocoll is known as a synthetic compound, but until now had not been isolated as a natural product from a microorganism. The compound showed biological activity against various Arthrobacter strains, filamentous fungi, several pathogenic protozoa, and some human tumor cell lines.