Miracle-dz/UniFAR-FTUs huggingface dataset:
Nonlinear dynamical properties of an oscillating tip–cantilever system in the tapping mode

The dynamical properties of an oscillating tip–cantilever system are now widely used in the field of scanning force microscopy. The aim of the present work is to get analytical expressions describing the nonlinear dynamical properties of the oscillator in noncontact and intermittent contact situations in the tapping mode. Three situations are investigated: the pure attractive interaction, the pure repulsive interaction, and a mixing of the two. The analytical solutions obtained allow general trends to be extracted: the noncontact and the intermittent contact show a very discriminate variation of the phase. Therefore the measurement of the phase becomes a simple way to identify whether or not the tip touches the surface during the oscillating period. It is also found that the key parameter governing the structure of the dynamical properties is the product of the quality factor by a reduced stiffness. In the attractive regime, the reduced stiffness is the ratio of an attractive effective stiffness and the cantilever one. In the repulsive regime, the reduced stiffness is the ratio between the contact stiffness and the cantilever one. The quality factor plays an important role. For large values of the quality factor; it is predicted that a pure topography can be obtained whatever the value of the contact stiffness. For a smaller quality factor, the oscillator becomes more sensitive to change of the local mechanical properties. As a direct consequence, varying the quality factor, for example with a vacuum chamber, would be a very interesting way to investigate soft materials either to access topographic information or nanomechanical properties.
Overexpression of the COX2 translational activator, Pet111p, prevents translation of COX1 mRNA and cytochrome c oxidase assembly in mitochondria of Saccharomyces cerevisiae

Dramatically elevated levels of the COX2 mitochondrial mRNA‐specific translational activator protein Pet111p interfere with respiratory growth and cytochrome c oxidase accumulation. The respiratory phenotype appears to be caused primarily by inhibition of the COX1 mitochondrial mRNA translation, a finding confirmed by lack of cox1Δ::ARG8m reporter mRNA translation. Interference with Cox1p synthesis depends to a limited extent upon increased translation of the COX2 mRNA, but is largely independent of it. Respiratory growth is partially restored by a chimeric COX1 mRNA bearing the untranslated regions of the COX2 mRNA, and by overproduction of the COX1 mRNA‐specific activators, Pet309p and Mss51p. These results suggest that excess Pet111p interacts unproductively with factors required for normal COX1 mRNA translation. Certain missense mutations in PET111 alleviate the interference with COX1 mRNA translation but do not completely restore normal respiratory growth in strains overproducing Pet111p, suggesting that elevated Pet111p also perturbs assembly of newly synthesized subunits into active cytochrome c oxidase. Thus, this severe imbalance in translational activator levels appears to cause multiple problems in mitochondrial gene expression, reflecting the dual role of balanced translational activators in cooperatively regulating both the levels and locations of organellar translation.
Model Transient Networks from Strongly Hydrogen-Bonded Polymers

Random copolymers consisting of n-butyl acrylate backbones with quadruple hydrogen-bonding side chains based on 2-ureido-4[1H]-pyrimidinone (UPy) have been synthesized via controlled radical polymerization and postpolymerization functionalization. Through this synthetic strategy high UPy monomer content (15 mol %) can be reached while maintaining low polydispersity and excellent control over molecular weight, providing model reversible networks with well-defined molecular architecture. Despite low Tgs and a lack of entanglements or crystallinity, these materials behave as thermoplastic elastomers through the strong but reversible association of UPy groups. Bulk properties such as the plateau modulus, tensile modulus, and relaxation time scale are primarily determined by the average distance between UPy’s along the chain. Starting from a difunctional initiator, triblock copolymers can also be synthesized containing a homopolymer midblock and random copolymer end blocks, effectively concentrating the hydrog.
Guide Manifold Alignment by Relative Comparisons

When we are faced with data, one common task is to learn the correspondence relationship between different data sets. More concretely, by learning data correspondence, samples that share similar intrinsic parameters, which are often hard to estimate directly, can be discovered. For example, given some face image data, an alignment algorithm is able to find images of two different persons with similar poses or expressions. We call this technique the alignment of data. Besides its usage in data analysis and visualization, this problem also has wide potential applications in various fields. For instance, in facial expression recognition, one may have a set of standard labeled images with known expressions, such as happiness, sadness, surprise, anger and fear, of a particular person. Then we can recognize the expressions of another person just by aligning his/her facial images to the standard image set. Its application can also be found directly in pose estimation. One can refer to (Ham, Lee & Saul, 2005) for more details. Although intuitive, without any premise this alignment problem can be very difficult. Usually, the samples are distributed in high-dimensional observation spaces, and the relation between features and samples’ intrinsic parameters can be too complex to be modeled explicitly. Therefore, some hypotheses about the data distribution are made. In the recent years, the manifold assumption of data distribution has been very popular in the field of data mining and machine learning. Researchers have realized that in many applications the samples of interest are actually confined to particular subspaces embedded in the high-dimensional feature space (Seung & Lee, 2000; Roweis & Saul, 2000). Intuitively, the manifold Section: Knowledge and Organizational Learning
Lysophosphatidic acid-induced Ca(2+) mobilization in the neural retina of chick embryo.

Lysophosphatidic acid (LPA) plays various roles in the regulation of cell growth as a lipid mediator. We studied the effect of LPA on intracellular Ca(2+) concentration ([Ca2+]i) with Fura-2 in the neural retina of chick embryo during neurogenesis. Bath application of LPA (1-100 microM) to the embryonic day 3 (E3) chick retina caused an increase in [Ca2+](i) in a dose-dependent manner, with an EC(50) value of 9.2 microM. The Ca(2+) rise was also evoked in a Ca(2+)-free medium, suggesting that release of Ca(2+) from intracellular Ca(2+) stores (Ca(2+) mobilization) was induced by LPA. U-73122, a blocker of phospholipase C (PLC), inhibited the Ca(2+) rise to LPA. Pertussis toxin partially inhibited the Ca(2+) rise to LPA, indicating that G(i)/G(o) protein was at least partially involved in the LPA response. The developmental profile of the LPA response was studied from E3 to E13. The Ca(2+) rise to LPA declined drastically from E3 to E7, in parallel with decrease in mitotic activity of retinal progenitor cells. The signal transduction pathway and developmental profile of the Ca(2+) response to LPA were the same as those of the Ca(2+) response to adenosine triphosphate (ATP), which enhances the proliferation of retinal progenitor cells. The coapplication of LPA with ATP resulted in enhancement of Ca(2+) rise in the E3 chick retina. Our results show that LPA induces Ca(2+) mobilization in the embryonic chick retina during neurogenesis.
Effect of hydroxyurea on the rheological properties of sickle erythrocytes in vivo

We have monitored the rheological effects of hydroxyurea (HU) on erythrocytes obtained from two patients with severe sickle cell anemia who were enrolled in a therapeutic trial of this drug. Erythrocyte membrane stability and whole cell and membrane deformability of red cells from treated and untreated patients and normal controls were determined in room air using an ektacytometer—a laser viscodiffractometer. The percentage of dense cells was quantitated by centrifugation on a discontinuous Stractan density gradient. F reticulocytes (FR), absolute F reticulocytes (AFR), and F cells (FC) were determined by single‐cell radial immunolgic assays. After 1 year of treatment with HU, there was a significant increase in the level of hemoglobin (Hb) F, FR, AFR, and FC. The degree of anemia remained the same, but there was significant increase in the mean cell volume (MCV) and a significant decrease in the mean corpuscular Hb concentration (MCHC). Whole cell deformability improved by twofold, but membrane stability remained within normal limits. The hydration status of sickle erythrocytes improved as was indicated by a change toward normal in gradient osmotic ektacytometry, an increase in RBC K+ content, a decrease in percent of dense cells, and a decrease in the MCHC. The data indicate that, in addition to its effect on the production of Hb F, HU has a salutary effect on whole cell deformability and on the hydration status of sickle erythrocytes. Determination of the rheological properties of erythrocytes may be of value in monitoring the response to HU.
Attachment of an anti-receptor antibody to non-target cells renders them susceptible to lysis by a clone of cytotoxic T lymphocytes.

The molecular basis for the dependence of antigen recognition by T cells on products of the major histocompatibility complex (MHC) is unknown, and the antigenic structures that are actually bound by T-cell receptors are ill-defined. In this study, we asked whether a monoclonal antibody (mAb) that reacts with the T-cell receptor of a clone of murine cytotoxic T lymphocytes (CTL) and not with the receptors of other CTL clones can substitute for that clone's natural ligand in specific cytolytic reactions. To answer the question, a mAb (1B2) to the receptor of a CTL clone (2C) was attached covalently to 51Cr-labeled cells that were not otherwise susceptible to lysis by clone 2C, and the cells thus modified were then tested as targets for clone 2C and other CTL clones of similar specificity. All labeled cells modified in this way, including a murine cell line that expresses no cell-surface MHC class I molecules and a human cell line, were lysed by clone 2C but not by other CTL clones. If, however, instead of attaching the mAb to the receptor of clone 2C, the cells were modified by attaching to them mAbs to other surface antigens on CTL [lymphocyte function-associated antigen (LFA-1), Thy-1.2], they were not lysed. In cytolytic titrations, the cells that had been converted by attachment of mAb 1B2 into specific targets for clone 2C were just as susceptible to lysis by that clone as the clone's natural H-2d targets (e.g., P815 cells). However, some accessory surface molecules (LFA-1, Lyt-2) that are required for clone 2C to lyse its natural H-2d targets seemed not to be required for this clone to lyse the mAb-converted target cells. By demonstrating that a variety of different cell types can be thus converted into target cells for CTL, the approach described in this study may provide opportunities to analyze further the mechanisms by which CTL destroy target cells.
Anti‐tumor activity of a blocked ricin immunotoxin with specificity against the cluster‐5A antigen associated with human small‐cell lung cancer

The monoclonal antibody (MAb) SEN3I, a mouse IgG1 which recognizes the cluster‐5a antigen on small‐cell lung cancer (SCLC) cells, was used to prepare a selective and potent blocked ricin immunotoxin. In a series of experiments in vitro and in a SCLC xenograft model in nude mice, the tumor localization potential of the radiolabeled antibody SEN31 and the anti‐tumor activity of the immunotoxin SEN31‐bR, the non‐specific binding activity of which had been greatly reduced by blocking of the galactose binding domains of the B‐chain, was determined. Radiolabeling of SEN31 was performed by linking a 67Ga‐labeled desferrioxamine moiety to the oligosaccharide side chains of the antibody in order to preserve the specific cell‐binding activity. 67Ga‐SEN31 bound to the antigenic sites on cells of the SW2 SCLC cell line, with a dissociation constant of 3.5 nM and, when injected i.v. , selectively localized at the site of s.c. ‐growing SW2 tumor xenografts in nude mice, with a tumor‐to‐blood ratio of 3.5. The immunotoxin SEN31 ‐bR was potently and selectively active against SCLC cell lines both of classic and of variant morphologies. At a concentration of 300 pM the immunotoxin selectively eliminated 4.5 logs of clono‐genic tumor cells. In nude mice, SEN31 ‐bR was cleared from the blood with biphasic kinetics following i.v. injection and maintained a stable serum level during continuous i.p. infusion. The growth of s.c. SW2 solid‐tumor xenografts was delayed following a single i.v. injection or a continuous i.p. infusion, each at a non‐toxic dose.
Presence and analysis of large plasmids in Oenococcus oeni.

The use of a large-scale isolation technique to screen 30 Oenococcus oeni strains for extrachromosomal DNA led to the finding of large plasmids (ca. 40 kb) in most of the strains as well as the finding of small plasmids (2.5 to 4.5 kb) in 6 of the strains. The circular nature of the large plasmids was assessed by electrophoresis in ethidium bromide continuous gradient gels and the different conformations of these elements could be distinguished by three run types of pulsed-field gel electrophoresis (PFGE). Southern hybridization with PFG-electrophoresed DNA also suggested that the low extraction yields of these probably low-copy-number plasmids could be related to the generation of the OC conformation resulting from nicking during cell lysis. The results seem to indicate that the occurrence of large plasmids in O. oeni may be more frequent than is usually considered, although their presence is difficult to ascertain. Furthermore, spontaneous curing of these elements might occur. In fact, plasmid pOg25 (37 kb) was eventually not detected by DNA-DNA hybridization in its original host strain.
Cloning, nucleotide sequence, and regulation of katE encoding a sigma B-dependent catalase in Bacillus subtilis

A sigma B-dependent stress gene of Bacillus subtilis was localized downstream of the licS gene. The predicted amino acid sequence exhibited a significant similarity to the sequence of the katE-encoded catalase HPII of Escherichia coli, and we designated it the open reading frame katE. In a B. subtilis katE mutant, catalase 2 could not be detected. The amount of katE-specific mRNA was increased after heat, salt, or ethanol stress or after glucose starvation in a sigma B-dependent manner. As in E. coli, the transcription of the katE gene in B. subtilis was unaffected by the addition of H2O2 to exponentially growing cells. In contrast, the katA gene encoding catalase 1 of B. subtilis showed an induction pattern different from that of katE; katA expression was strongly increased by oxidative stress. The similarity between E. coli sigma S-dependent genes and B. subtilis sigma B-dependent genes suggests that both may confer multiple stress resistance to stationary-phase cells.
Salient Region Detection by Tuning Spectrum Based on Lateral Inhibition

Detection of visually salient image regions is useful for applications like object segmentation, adaptive compression and object recognition. In this paper, we introduce a method for salient region detection using spectrum tuning based on lateral inhibition mechanism. The new method tunes the Fourier spectral adaptively using nonlinear function to inhibit the redundant image features and enhance the salient image features, and therefore the salient region could be detected effectively. We test this method on both real natural images and artificial pictures such as psychological patterns. Experimental results indicate that our method is more efficient than other methods in terms of detection rate, boundary integrity and contrast of salient region.
Infrequent Mutation of the p53 Gene in Fibrous Tumors of Infancy and Childhood

Mutations in the p53 tumor suppressor gene occur in >50% of human malignancies, but are exceedingly rare in benign tumors. The malignant potential of fibrous tumors of children may be unpredictable at microscopic examination. We therefore sought to determine whether malignant fibrous tumors could be distinguished from their benign counterparts by the presence of mutations in p53. We screened 27 fibrous tumor samples from 20 young patients. Tumors were classified as benign, borderline, or malignant by conventional microscopic criteria. RNA extracted from each specimen was used as the template for reverse transcription followed by polymerase chain reaction (PCR) amplification, with six pairs of primers covering the whole coding region of the p53 gene. All PCR products were screened for the presence of mutations using single-strand conformation polymorphism analysis. In addition. PCR products encompassing exons 5–9. the sites of the most frequent mutations in human tumors, were sequenced directly. Both methods detected a single point mutation in a highly malignant tumor (malignant fibrous histiocytoma). The mutation was a silent one at codon 36 (CCG-CCA, Pro-Pro). We conclude that p53 mutations are infrequent in childhood fibrous tumors. consistent with previous observations of low malignant potential (<10%) and better prognosis in this tumor group. Therefore, screening for p53 mutations is not a useful prognostic indicator in fibrous tumors with borderline pattern at microscopic examination.
Mechanism of Human Group V Phospholipase A2(PLA2)-induced Leukotriene Biosynthesis in Human Neutrophils

Human group V phospholipase A2(hVPLA2) has been shown to have high activity to elicit leukotriene production in human neutrophils (Han, S. K., Kim, K. P., Koduri, R., Bittova, L., Munoz, N. M., Leff, A. R., Wilton, D. C., Gelb, M. H., and Cho, W. (1999)J. Biol. Chem. 274, 11881–11888). To determine the mechanism by which hVPLA2 interacts with cell membranes to induce leukotriene formation, we mutated surface cationic residues and a catalytic residue of hVPLA2 and measured the interactions of mutants with model membranes, immobilized heparin, and human neutrophils. These studies showed that cationic residues, Lys7, Lys11, and Arg34, constitute a part of the interfacial binding surface of hVPLA2, which accounts for its moderate preference for anionic membranes. Additionally, hVPLA2 binds heparin with high affinity and has a well defined heparin-binding site. The site is composed of Arg100, Lys101, Lys107, Arg108, and Arg111, and is spatially distinct from its interfacial binding surface. Importantly, the activities of the mutants to hydrolyze cell membrane phospholipids and induce leukotriene biosynthesis, when enzymes were added exogenously to neutrophils, correlated with their activities on phosphatidylcholine membranes but not with their affinities for anionic membranes and heparin. These results indicate that hVPLA2 acts directly on the outer plasma membranes of neutrophils to release fatty acids and lysophospholipids. Further studies suggest that products of hVPLA2 hydrolysis trigger the cellular leukotriene production by activating cellular enzymes involved in leukotriene formation. Finally, the temporal and spatial resolution of exogenously added hVPLA2 and mutants suggests that binding to cell surface heparan sulfate proteoglycans is important for the internalization and clearance of cell surface-bound hVPLA2.
Obstetric causes for delivery of very-low-birth-weight babies at Tygerberg Hospital.

from the analysis as they had a birth weight exceeding 1 499 g. Results. Primary causes of delivery were hypertensive disease in 101 patients (44.7%), spontaneous preterm labour 65 (28.8%), preterm prelabour rupture of membranes 21 (9.3%), intrauterine death 17 (7.5%), antepartum haemorrhage 10 (4.4%), congenital abnormalities 3 (1.3%), and other 9 (4%). Of the hypertensive cases, 43 were delivered for fetal distress, 16 for fetal distress due to abruptio placentae, 20 for maternal reasons, 19 for intrauterine death and 3 for both fetal and maternal reasons. Conclusion. Hypertension, preterm labour and prelabour rupture of membranes were the main causes of delivery of VLBW babies. Further research should address methods to reduce the number of these deliveries. S Afr J Med 2003; 93: 61-64.
Bilateral septic arthritis of the knee secondary to group G streptococcal endocarditis

We report on an 81-year-old male with bilateral septic arthritis of the knee joints, who was treated with multiple joint washouts and intravenous antibiotics. As far as we know, there has been no case report in the English literature, on bilateral septic arthritis of the knee secondary to group G b-haemolytic streptococcal endocarditis.
Modeling and Calibration in Near-Field Microwave Microscopy for Dielectric Constant and Loss Tangent Measurement

The characterization of liquid samples using evanescent microwave fields is described. A calibration model is developed to relate the measured near-field reflection coefficient to the local properties of the sample under test. As a demonstration, permittivity extraction of different sodium chloride solutions is experimentally determined. The accuracy of 0.3% and 1.3% is obtained for the dielectric constant and the loss tangent at 2.45 GHz.
Conditional-event usage testing

In limited applications, operational profile testing has been shown to increase productivity, improve customer satisfaction, and reduce cost and time to market [4, 1, 5]. Unfortunately, underlying assumptions of this method make it generally inapplicable to the large class of software for which dependencies exist among the software's operations [2]. We propose conditional-event usage testing (CEUT), which will retain the benefits of traditional operational profile testing but which is not limited in the class of systems to which it applies. In CEUT, the expected usage of the software is modeled in such a way as to allow specification of conditions upon expected input event sequences. The model is used to generate test cases which will exercise the software in a fashion typical of actual operation. For systems with dependencies among operations, using CEUT resulted in test sequences that were typical of those experienced in operation, and allowed the benefits of operational profile-type testing to be realized on such systems.
The measurement of visual acuity in children: an evidence‐based update

Over the past decade, a number of large clinical trials have provided important information relating to the reliability and repeatability of commonly used paediatric tests of vision and their role in the diagnosis and management of paediatric ocular diseases. The aim of this review is to summarise recent findings on the use of paediatric visual acuity tests in clinical practice and to discuss the validity and accuracy of visual acuity measurements in infants and young children. We provide a broad overview of the benefits and challenges of measuring visual acuity in children and then discuss age‐appropriate tests for measuring visual acuity in infants through to school‐age children. We also discuss normative values for visual acuity in each age group and, where possible, provide comparisons of results between tests with a particular focus on the importance of optotype design.
The Upside Potential of Hiring Risky Workers: Evidence from the Baseball Industry

Making use of performance data for baseball players, this article provides empirical evidence in support of Lazear’s (1998) theoretical predictions that (1) risky workers will earn a premium for their upside potential, (2) this risk premium will be higher the longer a worker’s work life, and (3) firms must enjoy some comparative advantage in the labor market to be willing to pay a premium to risky workers. The validity of Lazear’s predictions carries implications for wage differentials between young and old workers and between men and women.