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PubMed2004

D-term inflation without cosmic strings.

We present a superstring-inspired version of D-term inflation that does not lead to cosmic string formation and appears to satisfy the current cosmic microwave background constraints. It differs from minimal D-term inflation by a second pair of charged superfields that makes the strings nontopological (semilocal). The strings are also Bogomol'nyi-Prasad-Sommerfield strings, so the scenario is expected to survive supergravity corrections. The second pair of charged superfields arises naturally in several brane and conifold scenarios, but its effect on cosmic string formation had not been noticed so far.

Journal Article↗

PubMed2004

Combining strings and necklaces for interactive three-dimensional segmentation of spinal images using an integral deformable spine model.

Segmentation of the spine directly from three-dimensional (3-D) image data is desirable to accurately capture its morphological properties. We describe a method that allows true 3-D spinal image segmentation using a deformable integral spine model. The method learns the appearance of vertebrae from multiple continuous features recorded along vertebra boundaries in a given training set of images. Important summarizing statistics are encoded into a necklace model on which landmarks are differentiated on their free dimensions. The landmarks are used within a priority segmentation scheme to reduce the complexity of the segmentation problem. Necklace models are coupled by string models. The string models describe in detail the biological variability in the appearance of spinal curvatures from multiple continuous features recorded in the training set. In the segmentation phase, the necklace and string models are used to interactively detect vertebral structures in new image data via elastic deformation reminiscent of a marionette with strings allowing for movement between interrelated structures. Strings constrain the deformation of the spine model within feasible solutions. The driving application in this work is analysis of computed tomography scans of the human lumbar spine. An illustration of the segmentation process shows that the method is promising for segmentation of the spine and for assessment of its morphological properties.

Aged↗

PubMed2004

Effects of classifier structures and training regimes on integrated segmentation and recognition of handwritten numeral strings.

In integrated segmentation and recognition of character strings, the underlying classifier is trained to be resistant to noncharacters. We evaluate the performance of state-of-the-art pattern classifiers of this kind. First, we build a baseline numeral string recognition system with simple but effective presegmentation. The classification scores of the candidate patterns generated by presegmentation are combined to evaluate the segmentation paths and the optimal path is found using the beam search strategy. Three neural classifiers, two discriminative density models, and two support vector classifiers are evaluated. Each classifier has some variations depending on the training strategy: maximum likelihood, discriminative learning both with and without noncharacter samples. The string recognition performances are evaluated on the numeral string images of the NIST Special Database 19 and the zipcode images of the CEDAR CDROM-1. The results show that noncharacter training is crucial for neural classifiers and support vector classifiers, whereas, for the discriminative density models, the regularization of parameters is important. The string recognition results compare favorably to the best ones reported in the literature though we totally ignored the geometric context. The best results were obtained using a support vector classifier, but the neural classifiers and discriminative density models show better trade-off between accuracy and computational overhead.

Algorithms↗

PubMed2005

Methodology and transport medium for collection of Helicobacter pylori on a string test in remote locations.

BACKGROUND: Helicobacter pylori can be isolated from patients using the string test but contaminating oral and nasopharyngeal microflora need to be suppressed by rapid plating out onto selective culture media. Recently, use of this diagnostic method was enhanced by using a novel transport medium to collect specimens from subjects in a remote Australian clinic over 1300 km from the laboratory. METHODS: Retrieved string tests were transported to the laboratory in chilled polystyrene boxes in 5 ml screw-cap bottles with 3 ml of a brain heart infusion broth plus antibiotics. These were 20 g/ml vancomycin, 10 g/ml trimethoprim, 10 g/ml cefsulodin, and 10 g/ml amphotericin B. A comparison was made between subjects who gargled with a chlorhexidine mouthwash before swallowing the string test and those who did not. RESULTS: Forty-five urea breath test-positive subjects were tested and H. pylori was isolated from 34 of them. Successful culture was achieved from string tests that were in transit for up to 29 hours and where the maximum temperature in the transport box was 14 degrees C. The additional use of a mouthwash had a marked effect on the isolation rate. H. pylori was cultured from 75% of subjects who gargled but only from 39% who did not. CONCLUSIONS: This methodology and transport medium can broaden the use of the string test to more remote geographic areas where endoscopy is not feasible so that H. pylori isolates may still be obtained for diagnostic and epidemiologic studies. The value of this promising methodology of collection and transport should be assessed in a controlled study.

Adolescent↗

PubMed2006

Formation of platelet strings and microthrombi in the presence of ADAMTS-13 inhibitor does not require P-selectin or beta3 integrin.

BACKGROUND: Ultra-large von Willebrand factor (ULVWF) and the receptor P-selectin are released from endothelial Weibel-Palade bodies during injury or inflammation. VWF mediates platelet adhesion and P-selectin promotes leukocyte rolling. ADAMTS-13 limits the duration of platelet adhesion by cleaving the ULVWF. In the absence of ADAMTS-13, long VWF filaments decorated with platelets form. Recent in vitro studies suggested that P-selectin might anchor these platelet strings to endothelium, but whether the same mechanism exists in vivo remains to be elucidated. METHODS: We address the role of P-selectin and beta(3) integrin in platelet string formation in vivo using intravital microscopy by infusing inhibitory ADAMTS-13 antibody in P-selectin-/- and beta(3)-deficient mice and activating the endothelium by injecting histamine. RESULTS: We show that inhibition of ADAMTS-13 combined with endothelial activation leads to similar extents of platelet string formation in wild-type, P-selectin- and integrin beta(3)-deficient mice. Further, in venules the platelet strings can coalesce into VWF-platelet aggregates. This process utilizes neither the platelet beta(3) integrin nor P-selectin. We also show in vitro that platelets can act as a bridge between the VWF fibers and that VWF can self-associate even in areas devoid of platelets. CONCLUSIONS: The formation or retention of the platelet strings does not require P-selectin or the endothelial VWF receptor alpha(v)beta(3). Furthermore, in the presence of low ADAMTS-13 activity, VWF-dependent and alpha(IIb)beta(3)-independent platelet clustering occurs in veins, as has been shown at high arterial shear rates. Our study further supports the importance of regulation of VWF multimer size upon secretion from Weibel-Palade bodies.

ADAMTS13 Protein↗

PubMed2005

Feasibility and safety of string wireless capsule endoscopy in the diagnosis of esophageal varices.

OBJECTIVE: To assess the feasibility, safety, accuracy, and acceptability of "string-capsule endoscopy" in the evaluation of esophageal varices. MATERIAL AND METHODS: Strings were attached to the wireless capsule endoscopy device to allow its controlled movement up and down the esophagus. Time of recording and discomfort associated with the procedure was documented. Patient's preference compared to conventional esophago-gastro-duodenoscopy (EGD) was recorded. An independent endoscopist blinded to EGD diagnoses assessed the diagnostic accuracy of pictures obtained. RESULTS: Thirty patients with clinical liver cirrhosis (mean age: 54.4 yr; mean MELD score: 12.5, and mean Child-Pugh score: 6.3) were enrolled; 19 for surveillance and 11 for screening purposes. The procedure was safe (no strings were disrupted and no capsule was lost). The mean recording time was 5.8 min (2.9-8.7), the accuracy 96.7%, and discomfort was minimal. The majority (83.3%) of patients preferred string-capsule endoscopy to EGD. CONCLUSIONS: String-capsule endoscopy was feasible, safe, accurate, highly acceptable, and preferred by cirrhotic patients undergoing screening/surveillance of esophageal varices. The technique may prove to be more cost effective than conventional EGD.

Adult↗

PubMed2003

The structural dynamics of the American five-string banjo.

The American five-string banjo is unique among musical instruments in that many significant parameters that effect tone are easily adjusted. This is probably why so many banjo players fiddle with their banjo. The instrument is a combination of canonical vibrating systems (strings, and a circular membrane) and therefore more amenable to analysis and modeling than most other musical instruments (e.g., the violin). Such an analysis is presented here. The model is a harmonically driven string which excites the other strings and a membrane under tension, causing the membrane to radiate sound. Three figures-of-merit, FOMs, are assumed. They are loudness, brightness, and decay of the sound. The effects of a number of parameters on the proposed FOMs are investigated. Among these are the loss factor and tension of the membrane, the mass of the bridge, and the location on the string of the excitation. It is noted that the calculated effects of the changes agree with generally accepted setup practices.

Acoustics↗

PubMed1975

Role of stimulus modality in rating ordinary and derived word strings.

Four types of word strings were presented either visually or auditorily and rated for grammaticality and meaningfulness. The string types were normal sentences, syntactically deviant strings, semantically deviant strings, and strings both syntactically and semantically deviant. Results for the auditory mode conform to expectations based upon the linguistic competence of the native speaker but results for the visual mode do not. The results are discussed in terms of the inferiority of visual over auditory short-term memory for verbal information and attentional strategies.

Attention↗

PubMed2005

Letter processing in the visual system: different activation patterns for single letters and strings.

One would expect that a lifetime of experience recognizing letters would have an important influence on the visual system. Surprisingly, there is limited evidence of a specific neural response to letters over visual control stimuli. We measured brain activation during a sequential matching task using isolated characters (Roman letters, digits, and Chinese characters) and strings of characters. We localized the visual word form area (VWFA) by contrasting the response to pseudowords against that for letter strings, but this region did not show any other sign of visual specialization for letters. In addition, a left fusiform area posterior to the VWFA was selective for letter strings, whereas a more anterior left fusiform region showed selectivity for single letters. The results of different analyses using both large regions of interest and inspections of individual patterns of response reveal a dissociation between selectivity for letter strings and selectivity for single letters. The results suggest that reading experience fine-tunes visual representations at different levels of processing. An important conclusion is that the processing of nonpronounceable letter strings cannot be assumed to be equivalent to single-letter perception.

Adult↗

PubMedDate not supplied

Purse-string sutures for hyperopia following radial keratotomy.

BACKGROUND: Five years ago, we presented 19 procedures employing two intrastromal purse-string sutures to treat hyperopic shift following radial keratotomy. Thirty-four additional procedures and longer follow-up are now presented detailing the task of rehabilitating these eyes. METHODS: Fifty-three eyes of 53 radial keratotomy patients who were unhappy with their uncorrected vision and who were dissatisfied with contact lens or spectacle correction underwent double corneal intrastromal purse-string suturing and were subsequently followed for at least 1 year. There were seven eyes with primary overcorrection and 46 eyes with progressive hyperopic shift. Spherical equivalent refraction before purse-string sutures ranged from +0.50 to +6.25 D (mean, +2.60 D, SD +/- 1.26 D). Prior to purse-string suturing, uncorrected visual acuity ranged from 20/30 to 20/400 with 21 eyes (45.3%) 20/100 or worse. RESULTS: The follow-up after suturing averaged 3.6 years (range, 1 to 10 yr). All patients had follow-up of at least 1 year. The steepening in average keratometric power was 2.94 +/- 1.72 D (range, 1.06 to 6.68 D). The sherical equivalent refraction after suturing averaged -0.15 +/- 1.17 D (range, +3.75 to -2.50 D). Uncorrected visual acuity after suturing was 20/40 or better in 38 eyes (72%) and 20/50 to 20/100 in 15 eyes (28%). The number of eyes with a spherical equivalent refraction of +/- 0.50 D with 0.50 D or less refractive astigmatism was 15 (26% of eyes). There were 34 eyes (66%) with +/- 1.00 D with 1.00 D or less of refractive astigmatism, and 42 eyes (78%) with +/- 2.00 D with 2.00 D or less refractive astigmatism. Most of the spread was on the myopic side, as intended. There were no significant intraoperative or postoperative complications. Fifteen eyes gained two or more lines of best spectacle-corrected visual acuity and no eyes lost one line. CONCLUSION: Double intrastromal purse-string suturing produces steepening of the central cornea and reduces hyperopia after radial keratotomy.

Adult↗

PubMed1999

Computed tomography of humans and bowed stringed instruments. Some interesting similarities.

We have used computed tomography to evaluate bowed stringed instruments and have noted interesting analogies with CT scans of humans. In humans, CT commonly detects a broad range of normal anatomic variations. Similarly, CT of violins and cellos demonstrates a wide range of normal structural variations. CT, often used to detect infections in humans, also detects defects from wood infestations. In humans, the unrelenting effect of gravity causes deformity of the demineralized spine. In old stringed instruments, plastic deformity of wood results from unrelenting string pressure. Trauma causes bone fractures in humans and wood fractures in bowed stringed instruments, and repairing fractures in both humans and stringed instruments requires various splitting devices. In summary, CT provides the physician and the luthier with a unique, noninvasive tool that can characterize the broad range of normal structures, pathological conditions, and repair.

Fractures, Bone↗

PubMed2003

Key-string algorithm--novel approach to computational analysis of repetitive sequences in human centromeric DNA.

AIM: To use a novel computational approach, Key-string Algorithm (KSA), for the identification and analysis of arbitrarily large repetitive sequences and higher-order repeats (HORs) in noncoding DNA. This approach is based on the use of key string that plays a role of an arbitrarily constructed "computer enzyme". METHOD: A cluster of novel KSA-related methods was introduced and developed on the basis of a combination of computations on a very modest scale, by eye inspection and graphical display of results of analysis. Sequence analysis software was developed, containing seven programs for KSA-related analyses. This approach was demonstrated in the case study of alpha satellites and HORs in the human genetic sequence AC017075.8 (193277 bp) from the centromeric region of human chromosome 7. The KSA segmentation method was applied by using DCCGTTT, GTA, and TTTC key strings. RESULTS: Fifty-five copies of 2734-bp 16mer HORs were identified and investigated, and a start-string TTTTTTAAAAA was identified. The HOR-matrix was constructed and employed for graphical display of mutations. KSA identification of HORs in AC017075.8 was compared with that of RepeatMasker and Tandem Repeat Finder, which identified alpha monomers in AC017075.8, but not the HORs. On the basis of KSA study, the centromere folding was described as an effect of HORs and super-HORs (3 x 2734 bp) in AC017075.8. The following novel computational KSA-based methods, easy-to-use and intended for computational "pedestrians", were demonstrated: color-HOR diagram, KSA-divergence method, 171-bp subsequence-convergence diagram, and total frequency distribution of the key-string subsequence lengths. The results were supplemented by Fast Fourier Transform, employing a novel mapping of symbolic genomic sequence into a numerical sequence. CONCLUSION: The KSA approach offers a simple and robust framework for a wide range of investigations of large repetitive sequences and HORs, involving a very modest scope of computations that can be carried out by using a PC. As the KSA method is HOR-oriented, the identification of HORs is even easier than the identification of underlying alpha monomer itself. This approach provides an easy identification of point mutations, insertions, and deletions, with respect to consensus. This may be useful in a wide range of investigations and applied in forensic medicine, medical diagnosis of malignant diseases, biological evolution, and paleontology.

Algorithms↗

PubMedDate not supplied

[Value of the string test in the diagnosis of duodenal parasitosis].

Diagnosis of small intestine parasitosis can be realized by string-test. This examination, easily performed, does not produce side-effects in ninety percent of cases. The main problems are: good string unrollment and duodenal passing over. When Necator ova or gardia cysts are found in the stools by the Junod's technic, string-test is always positive. In one case, this latter even showed Schistosoma mansoni ova. Among 18 patients with unexplained hypereosinophilia, in spite of a parasitologic check up involving three stools examinations, the string-test showed Necator ova. With regard to strongyloidiasis, when properly performed, string-test is positive in seventy percent of cases. Therefore, this technic seems very useful on the field or in laboratories which do not usually realize the Junod's technic.

Adolescent↗

PubMed1995

Drosophila development pulls the strings of the cell cycle.

The three cycles of cell division immediately following the formation of the cellular blastoderm during Drosophila embryogenesis display an invariant pattern. Bursts of transcription of a gene called string are required and sufficient to trigger mitosis at this time during development. The activator of mitosis encoded by the string gene is a positive regulator of cdc2 kinase and a Drosophila homologue of the Saccharomyces pombe cdc25 tyrosine phosphatase. Evidence presented in a recent paper demonstrates that transcription of string, and hence the timing and pattern of mitosis in the postblastoderm embryo, is under complex developmental control. Several lines of evidence support this interpretation, including the analysis of string transcription in pattern formation mutants, cell cycle arrest mutants, and the preliminary characterization of an extensive cis-acting regulatory region.

Animals↗

PubMed1993

Purse-string suture for stapled oesophagogastric anastomosis: hand-sewn versus automatic.

An automatic purse-string device was compared with the traditional hand-sewn method in stapled oesophageal anastomosis. Fifteen greyhound dogs underwent distal oesophagectomy with stapled gastro-oesophageal anastomosis; a purse-string suture was used to draw the distal oesophagus around the stapling device. The animals were randomized into group 1 (n = 8), in which the automatic device was used, and group 2 (n = 7), in which the oesophageal purse string was hand-sewn. The automatic device failed to incorporate the oesophageal mucosa and submucosa reliably into the anastomotic staple line. There were five defective anastomoses in group 1 and none in group 2 (P = 0.037). Anastomotic bursting pressures were significantly reduced in group 1 compared with group 2 (median (range) 47 (22-110) versus 82 (68-88) mmHg, P = 0.032). Within group 1, a significant difference in bursting pressure existed between complete anastomoses and those in which the mucosa was not fully incorporated (median (range) 75 (60-110) versus 39 (22-50) mmHg, P = 0.037). Median (range) breaking strengths where anastomoses were incomplete were lower than where all layers were incorporated (1420 (1250-2220) versus 1990 (1590-2475) g/cm, P = 0.009). This study questions the safety of the automatic purse-string device for oesophageal anastomosis when used in accordance with present recommendations. Further evaluation and possibly modification of either the instrument design or the methods recommended by the manufacturer for its use are warranted.

Anastomosis, Surgical↗

PubMed2004

Musical training-induced functional reorganization of the adult brain: functional magnetic resonance imaging and transcranial magnetic stimulation study on amateur string players.

We used the combined technique of functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) to observe changes that occur in adult brains after the practice of stringed musical instruments. We carried out fMRI on eight volunteers (aged 20-22 years): five novices and three individuals who had discontinued practice for more than 5 years. The motor paradigm contained a repetitive lift-abduction/fall-adduction movement of the left/right little finger, carried out with maximum efforts without pacing. The sensory paradigm was to stimulate the same little finger using a string. In parallel to the fMRI acquisition, TMS motor maps for the little finger were obtained using a frameless stereotactic neuronavigation system. After the baseline study, each participant began to learn a stringed instrument. Newly developed fMRI activations for the left little finger were observed 6 months after practice at multiple brain regions including inferior parietal lobule, premotor area (PMA), left precuneus, right anterior superior temporal gyrus, and posterior middle temporal gyrus. In contrast, new activations were rarely observed for the right little finger. The TMS study revealed new motor representation sites for the left little finger in the PMA or supplementary motor area (SMA). Unexpectedly, TMS motor maps for the right little finger were reduced significantly. Among new fMRI activations for sensory stimuli of the left little finger, the cluster of highest activation was located in the SMA. Collectively, these data provide insight into orchestrated reorganization of the sensorimotor and temporal association cortices contributing to the skillful fingering and musical processing after the practice of playing stringed instruments.

Adult↗

PubMed1993

Assessment of olefin-based IUD tail strings.

The "tail string" that extends from a contraceptive intrauterine device (IUD) into the vagina is an illustrative case in materials engineering design. The strings must satisfy certain criteria for strength and other properties in order to fulfill the function of providing a means of insuring that the IUD has not been ejected, and eventually of helping remove the IUD. This must be done without contributing to an additional risk of unwanted medical side effects beyond those that may be inherent in any such device. Oriented monofilament olefins appear to satisfy these criteria, and have been used successfully in several IUD designs. This article describes a study of two such monofilaments taken from new IUDs, showing how the material's processing, structure, and properties lead to effective performance as tail strings. Several types of used IUDs were also studied, to insure that nothing occurred during use that would alter the conclusions drawn from the study of new strings.

Equipment Design↗

PubMed2000

Behavioral and brain wave evidence for automatic processing of orthographically regular letter strings.

Evidence for the automatic processing of nonword letter strings was sought in subjects who performed two different perceptual tasks. Twelve subjects detected valid words. Twelve other subjects detected Gestalt patterns that contained no letters. The targets and two types of nonword letter strings were interspersed in a stream of nonletter images. Behavioral data showed significant effects of orthographic regularity of letter strings in the group that detected words, but not in the group that detected Gestalt patterns. Brain-wave responses showed the effect of orthographic regularity in both groups. The responses were significantly larger for regular than for irregular strings. This showed that brain waves can be used to study the operation of reading processes in subjects who are performing a task that does not require reading ability.

Adult↗