Ristocetin- and thrombin-induced platelet aggregation at physiological shear rates: differential roles for GPIb and GPIIb-IIIa receptor

We recently reported that washed platelets (WP) activated with ADP and expressing surface-bound vWF aggregated in flow through small tubes or in a cylindrical couette device at physiological shear rates of G = 300 s(-1)-1000 s(-1) in the absence of exogenous ligands, with GPIb-vWF partially, and activated GPIIb-IIIa totally required for the aggregation. We have now extended these studies to aggregation of platelets "activated" with ristocetin or thrombin. Washed platelet suspensions with added soluble vWF and ristocetin (0.3-0.75 mg/ml), or activated with thrombin (0.01-0.5 U/ml) but no added ligand, were sheared in a coaxial cylinder device at uniform shear rate, G = 1000 s(-1). The collision capture efficiency (alphaG) with which small aggregates form (= experimental/calculated initial rates of aggregation) was correlated with vWF platelet binding assessed by flow cytometry. The vWF-GPIb interaction was exclusively able to support ristocetin-mediated shear aggregation of metabolically active platelets, with very few vWF monomer equivalents bound per platelet (representing < or = 10 molecules of 10 million Da) required to yield high capture efficiencies (alphaG = 0.38+/-.02; n = 11), suggesting rapid and stable bond formations between vWF and GPIb. However, platelet surface-expressed vWF, generated by addition of thrombin to washed platelets, was found to mediate platelet aggregation with alphaG = 0.08+/-.01 (n = 6), surprisingly comparable to that previously reported for WP and ADP activation. Blocking the GPIIb-Illa receptor decreased alphaG by 95+/-3% (n =3), while a monoclonal antibody to the vWF site on GPIb caused a 49+/-7% (n = 8) decrease in alphaG. The partial role for GPIb thus appears to reflect a facilitative function for increasing contact time between flowing platelets, and allowing engagement of the GPIIb-IIa receptor to yield stable attachment.     

Hernia survey of the Section on Surgery of the American Academy of Pediatrics

The members of the Section on Surgery of the American Academy of Pediatrics were surveyed to determine the practice of North American pediatric surgeons in infants with inguinal hernia (IH). Case-scenario multiple-choice-design questionnaires regarding hernias and hydroceles were sent to all members of the Surgical Section, and responses were received from 292 (50%). In healthy full-term infant boys with asymptomatic reducible IH, 82% of responders perform repair electively, no matter what the age or weight. In full-term girls with a reducible ovary, 59% perform surgery at the next available time; if the ovary is nonreducible but asymptomatic, 44% operate emergently or urgently and 42% at the next elective slot. In former preemies, the pattern of repair is as follows. (1) For those recently discharged after 2 months in the neonatal intensive care unit (NICU) with reducible IH, 65% perform the repair when convenient. (2) A general anesthetic is used in 70%; 15% use spinal anesthesia, and 11% use caudal block with sedation. (3) If the repair is done in the hospital outpatient (same-day) unit, 36% wait until 50 weeks postconception (PC) and 33% wait until 60 weeks PC. (4) if the baby's weight is at least 1,000 g. 71% perform the repair before discharge. The pain control choice after childhood IH repair is Tylenol for 30%, local infiltration biquivacaine for 30%, caudal block for 22%, regional block for 11%, and Tylenol/codeine combined for 7%. In 6-week-old full-term infants with communicating hydroceles without definite "hernia," two thirds treat as an IH with elective repair as soon as possible. With respect to contralateral exploration in infants with unilateral IH, 65% perform it in males if they are < or = 2 years of age and 84% use it in females of up to 4 years of age. This approach is not influenced by presenting side, presence of hydrocele, or history of prematurity. Laparoscopic evaluation of the contralateral IH is performed by only 6% of responders, 40% of whom use the open ipsilateral sac for laparoscope introduction.     

Correct behavior identification system in a Tagged World

This paper presents a system that is able to process the information provided by a Tagged World to identify user’s behavior and to produce alarms in dangerous situations. The system inputs are signals from sensors, which are used to recognize correct behavior (action sequences) by Inductive Learning, using Data Mining techniques. The inference engine is a reasoning device that is implemented by means of Regular Grammars. It permits us to control user’s behavior. As output, the system produces and sends alarms when a user action sequence is wrong, indicating the erroneous actions, forgotten future, and so on. To test our system, the Tagged World is supposed to be at a house, where we have used RFID technology to control the objects inside it.     

Application of polymerase chain reaction for the correlation of Salmonella serovars recovered from greyhound feces with their diet

The polymerase chain reaction was employed to correlate Salmonella serovars isolated from fecal material of greyhounds suffering from gastroenteritis with those isolated from the diet fed to the greyhounds prior to onset of diarrhea. Kennels around the Abilene, Kansas, area were contacted and supplied with materials needed to collect a portion of the diet each day. With the onset of diarrhea, the kennels were instructed to ship the fecal material and diet from the previous 10 days to the laboratory for testing. Forty-one fecal samples and corresponding diets were screened for Salmonella, Clostridium perfringens, Campylobacter jejuni, Staphylococcus aureus, Staphylococcus intermedius, and pathogenic (piliated) Escherichia coli by direct culture using standard procedures. The fecal material was also screened for coronavirus and parvovirus using electron microscopy. Thirty-five "normal" fecal samples were screened for all of the above mentioned microorganisms as a control. In addition, the fecal material was screened for E. coli verotoxins I and II and clostridial enterotoxins. A total of 61 Salmonella isolates were recovered from the 41 samples of feces and diet submitted for testing; 31 were recovered from the feces and 30 from the diet. Four Salmonella isolates were recovered from the normal fecal samples. Results obtained by PCR, plasmid profiles, antigenic analysis, and antibiogram profiles indicated that 16 of the 31 isolates recovered from the fecal material were the same strain as that recovered from the diet.     

Retrofit of RC hollow piers with CFRP sheets

Hollow bridge piers, particularly those built before the seventies, often have insufficient shear capacity due to inadequate transverse reinforcement details. Therefore, special attention must be given to this very important aspect when reinforced concrete (RC) piers with hollow sections are analysed and retrofitted. This paper covers the experimental analysis of retrofit solutions using CFRP sheets along the piers’ entire height to prevent shear failure. Experimental cyclic tests were carried out to evaluate the shear retrofit strategy efficiency on a set of RC piers with square hollow sections. This work also covers the study of design procedures for CFRP shear retrofitting and the evaluation of the associated ductility capacity improvement. The various transverse reinforcement detailing scenarios were assessed to determine their shear-failure prevention efficiency. The corresponding cyclic response behavior was also evaluated. The most relevant experimental information is presented in the paper, such as the evolution of the outer damage pattern. Finally, shear retrofit solutions, with a 40% increase over the maximum flexural force, show that this strategy is adequate to allow satisfactory ductility behavior.     

Efficient driver drowsiness detection at moderate levels of drowsiness

Previous research on driver drowsiness detection has focused primarily on lane deviation metrics and high levels of fatigue. The present research sought to develop a method for detecting driver drowsiness at more moderate levels of fatigue, well before accident risk is imminent. Eighty-seven different driver drowsiness detection metrics proposed in the literature were evaluated in two simulated shift work studies with high-fidelity simulator driving in a controlled laboratory environment. Twenty-nine participants were subjected to a night shift condition, which resulted in moderate levels of fatigue; 12 participants were in a day shift condition, which served as control. Ten simulated work days in the study design each included four 30-min driving sessions, during which participants drove a standardized scenario of rural highways. Ten straight and uneventful road segments in each driving session were designated to extract the 87 different driving metrics being evaluated. The dimensionality of the overall data set across all participants, all driving sessions and all road segments was reduced with principal component analysis, which revealed that there were two dominant dimensions: measures of steering wheel variability and measures of lateral lane position variability. The latter correlated most with an independent measure of fatigue, namely performance on a psychomotor vigilance test administered prior to each drive. We replicated our findings across eight curved road segments used for validation in each driving session. Furthermore, we showed that lateral lane position variability could be derived from measured changes in steering wheel angle through a transfer function, reflecting how steering wheel movements change vehicle heading in accordance with the forces acting on the vehicle and the road. This is important given that traditional video-based lane tracking technology is prone to data loss when lane markers are missing, when weather conditions are bad, or in darkness. Our research findings indicated that steering wheel variability provides a basis for developing a cost-effective and easy-to-install alternative technology for in-vehicle driver drowsiness detection at moderate levels of fatigue.     

Ontologies versus relational databases: are they so different? A comparison

Two main data models are currently used for representing knowledge and information in computer systems. Database models, especially relational databases, have been the leader in last few decades, enabling information to be efficiently stored and queried. On the other hand, ontologies have appeared as an alternative to databases in applications that require a more ‘enriched’ meaning. However, there is controversy regarding the best information modeling technique, as both models present similar characteristics. In this paper, we present a review of how ontologies and databases are related, of what their main differences are and of the mechanisms used to communicate with each other.     

Neutron irradiation effects on optical absorption of KU1 and KS-4V quartz glasses and Infrasil 301

In this work we have compared the effects of neutron (10²¹–10²² n/m² fluences) and gamma irradiation (23.8 MGy dose) on the IR–vis–UV optical absorption spectra of high purity silica with different OH content: KU1 (800 ppm), KS-4V (<0.2 ppm), and commercial silica Infrasil 301 (<8 ppm). The results show that the UV–vis optical degradation of the silica, after neutron irradiation at the highest fluence is similar for the three grades studied, while gamma-induced optical absorption depends on the material grade (KS-4V shows the lowest optical absorption). The effects of both types of radiation on the IR band related with the hydroxyl group (3650 cm⁻¹) depend on the silica grade. For KU1, the shape of this band changes with neutron fluence. For Infrasil 301 gamma and neutron irradiated, this band height increases, possibly due to free molecular or hydrogen atoms. The shift to lower energies observed for the 2260 cm⁻¹ band in the three neutron irradiated silica grades, reflects the changes induced by neutrons in the lattice bonding angle distribution.     

A theoretical model for the automatic generation of tag clouds

This paper presents a new approach to information retrieval from non-structured attributes in databases, which involves the processing of text attributes. To make retrieval more effective, frequent text sequences are extracted and mathematically represented as intermediate forms which permit a clearer and more precise definition of operations on texts. These intermediate forms appear to users in the form of tag clouds to facilitate content identification, exploration, and querying. In this sense, tag cloud visualization is a simple, user-friendly visual interface to data. This paper proposes a theoretical model for the representation of frequent text sequences and their operations as well as a general procedure for generating tag clouds from text attributes in databases. The tag clouds thus obtained were compared with conventional tag clouds composed of single terms. Our study showed that automatically generated multi-term tag clouds provide better results than mono-term tag clouds.     

Numerical Modelling of Thin-Walled Stainless Steel Structural Elements in Case of Fire

In this paper, the structural response of stainless steel thin-walled elements submitted to fire is analysed numerically by means of the geometrically and materially non-linear Finite Element program SAFIR, including imperfections. In order to make these simulations, two main changes in the program were made: (i) the code was changed in order to deal with the stainless steel 2D material constitutive law to be used with shell elements and (ii) the possibility of the program to take into account residual stresses with shell finite elements was introduced. The stainless steel stress–strain relationship at high temperatures was based on the one presented in part 1.2 of Eurocode 3. To model the strain hardening exhibited by the stainless steels, using the shell element formulation, an approximation to the Eurocode 3 constitutive law was needed. Local and global geometrical imperfections were considered in the simulations. The paper shows the influence of the residual stresses on the ultimate load-carrying capacity of thin-walled stainless steel structural elements in case of fire.