cssi/SciSciGPT-SciSciNet huggingface dataset:
In Vitro Nucleic Acid Amplification Techniques

Nucleic acid amplification (NAA) techniques have come of age. The specific amplification and detection of an oligonucleotide sequence went from the fictional to the mundane in the span of two decades. By looking at the theoretical basis for each method, NAA techniques can be placed into one of two broad categories: (i) target amplification systems, including PCR, ligase chain reaction (LCR), self-sustaining sequence amplification (3SR), nucleic acid sequence-based amplification (NASBA), transcription-based amplification system (TAS), transcription-mediated amplification (TMA), strand displacement amplification (SDA), and loop-mediated isothermal amplification (LAMP); and (ii) signal amplification systems (including probe amplification methods), such as branched-DNA technologies (bDNA) and cleavage-based signal amplification (cycling probe technologies [CPT] and Invader assays). Proofreading may help maintain fidelity of replication, and its absence can result in a relatively high rate of nucleotide incorporation errors (misincorporation), most relevant when starting with low target numbers. Misincorporation can produce amplicon mismatched to detection probes and can also result in inefficient amplification (especially when longer genetic stretches are targeted), due to primer mismatch in subsequent amplification rounds. Successful ligation relies on contiguous positioning and correct base pairing of the 3' and 5' ends of oligonucleotide probes on a target DNA molecule. The reliability of sequence data has improved, and the taxonomic and cytogenetic characterization of microorganisms has advanced tremendously. These improvements give the tools to allow the rapid and increasingly routine development of molecular methods for the identification, quantification, and characterization of microorganisms.
Robust micro-gated carbon nanotube field emitter arrays

An integrated gate (micro-gate) is necessary to enable field emission from carbon nanotubes (cNTs) at low voltages. We have demonstrated emission from cNTs grown inside two such types of micro-gated structures, one a gated silicon post, another having an open aperture. In the first configuration anode currents up to 1 mA (from 0.5 mm/sup 2/ area) were obtained at gate voltages as low as 40 V. In the second configuration the gate current was 2.5% of the anode current. The current was more stable than typical of most field emitter arrays, and the arrays did not fail by arcing at high currents. The emission current was increased by ambient water vapor and hydrogen, but was unaffected by xenon. Energy spectra of the emitted electrons show that the emission current saturated at energies just below the Fermi level, showing the electron transport to the emission site is requires a significant voltage.
Percutaneous removal of unraveled HELEX® septal occluder 4 months post deployment.

The GORE® HELEX® Septal Occluder (HSO: W.L. Gore & Associates; Flagstaff, AZ) is preferentially used at our institution for percutaneous closure of the patent foramen ovale (PFO). Adequate deployment of the device requires capture of three sequential eyelets by the locking loop. At times, the right atrial eyelet is not caught, particularly when a long tunnel PFO causes too much separation between the discs. Although rarely, unlocked devices have been left in the atrial septum with no untoward events provided they appear stable in the catheterization laboratory and the shunt has been eliminated. We report a patient in whom an unlocked, but otherwise well positioned, HSO subsequently unraveled with the right atrial disc migrating through the tricuspid valve while the left atrial disc remained well apposed to the left side of the atrial septum. The PFO was closed prior to liver transplantation to prevent an embolic event during the transplant. The patient required placement of several internal jugular central lines prior to transplant, and this instrumentation in the right atrium may have caused unraveling of the device. The HSO was removed percutaneously 15 weeks after implantation despite a well-seated and likely partially endothelialized left atrial disc. © 2015 Wiley Periodicals, Inc.
The flotation chemistry of potassium double salts: Schoenite, kainite, and carnallite

Abstract It is known from soluble salt flotation practice that the K, Mg double salts of kainite (KClMgSO43H2O), and carnallite (KClMgCl26H2O) are difficult to float and must be converted to other salts such as schoenite (K2SO4MgSO46H2O) and sylvite (KCl) in order to recover potash values. The flotation characteristics of these double salts have now been confirmed in some detail by carefully controlled laboratory experiments with both cationic and anionic collectors. The experimental results are discussed in view of recent experimental findings regarding the flotation characteristics of simple salts, in which the flotation response was shown to be determined by the interfacial water structure and whether the salt could be considered to be a water structure maker or a water structure breaker. The same approach can be use to explain the flotation response of the potassium double salts; schoenite, kainite, and carnallite. In addition, the sign of the surface charge of schoenite (K2SO4MgSO46H2O), was determined as a function of pH from nonequilibrium electrophoretic mobility measurements. Schoenite appears to exhibit three charge reversals (CR) which can be explained based on surface hydrolysis reactions. The flotation behavior of schoenite is further considered based on solution chemistry calculations, electrophoretic mobility measurements, and microflotation results.
The function of the tectum for attention to auditory stimuli in the cat

Cats were trained to avoid a shock by moving from one to the other compartment of a double grill box at the onset of a compound signal which consisted of a soft low tone and a bright flashing light. After training on the compound signal unreinforced test trials were given on the tone alone and the light alone. By this procedure the relative potency of sound and light was established for normal cats and cats deprived of various structures in their auditory system. On the basis of this and other subsidiary experiments also reported here, several conclusions seem warranted: 1. In normal cats sound is a prepotent stimulus over light. 2. The prepotency of sound does not depend on the intensities of the competing stimuli. 3. Even with approximately 90% of the second order auditory fibers destroyed, sound is still prepotent over light. 4. Bilateral removal of auditory cortex does not affect the prepotency of sound. 5. Deep bilateral section of the brachia of the inferior colliculus and small bilateral lesions in the apices of the inferior colliculi abolish the prepotency of sound. 6. The loss of the prepotency of sound after midbrain lesions is not the result of a change in absolute threshold for the sound.
pCruise: Reducing Cruising Miles for Taxicab Networks

In taxicab industry, a long standing challenge is how to reduce taxicab's mileage spent without a fare, i.e., cruising mile. The current solution for this challenge usually requires the participation of the passengers. To solve the issue without the passengers involved, in this paper, we propose a cruising system, pCruise, for taxicab drivers to maximize theirs profits by finding the optimal route to pick up a passenger, thus reducing the cruising mile. In pCruise, base on collected GPS records about other near taxicabs, a taxicab characterizes its cruising process with a cruising graph. When a taxicab becomes vacant and tries to find a passenger, cruising graph will provide the shortest cruising route with at least one expected available passengers for this taxicab. With the shortest cruising routes, taxicabs will significantly reduce theirs cruising miles. We evaluate pCruise based on a 7 days 10 GB real world GPS dataset from a city with more than 15,000 taxicabs. The evaluation results show that pCruise can assist taxicab drivers to reduce cruising miles by 41% on average.
Substituent effects on the barrier to carbamate C–N rotation

Abstract Seven aryl-substituted t -butyl N -methyl- N -aryl carbamates were prepared, and in each case, the barrier to C–N bond rotation, Δ G ‡ , was determined in CDCl 3 solution using variable temperature NMR. A linear free energy relationship is observed between Δ G ‡ and the electronic stabilization effect of the substituent on the N -aryl ring. More specifically, electron donating groups increase Δ G ‡ , whereas withdrawing groups decrease Δ G ‡ . A plot against σ – was more linear ( r 2 =0.96), than a plot against σ ( r 2 =0.90) or σ + ( r 2 =0.88) and a value of ρ =1.76 was obtained at 243 K. Thus, rotation about the carbamate C–N bond in weakly polar chloroform involves a decrease in positive charge on the nitrogen.
Simplexwise linear near-embeddings of a 2-disk into R2. II

Abstract Let K ⊂ R 2 be a finitely triangulated 2-disk; a map ƒ:K → R 2 is called simplexwise linear (SL) if f|σ is affine linear for each (closed) 2-simplex σ of K. Let L(K) = {SL homeomorphisms K → K fixing ∂K pointwise}, let L(K) denote its closure in the space of all SL maps K → R 2. In this paper it is proved that if K is strictly convex L(TK) is 1-connected.
Complications of laparoscopic procedures after concentrated training in urological laparoscopy.

Purpose: To increase the safety and efficiency of laparoscopic surgery clinical training programs have been developed to increase the skill and efficiency of urological trainees. We evaluated the impact of dedicated laparoscopy training on the rate and type of complications after trainees entered clinical practice.Materials and Methods: Data were obtained from 13 centers where laparoscopy was performed by a single surgeon with at least 12 months of training in urological laparoscopy before clinical practice. Data included training experience, laparoscopic procedures performed after commencing clinical practice and associated complications. Procedures were classified as easy, moderate and difficult.Results: During training each surgeon participated in a mean of 71 cases. In clinical practice a total of 738 laparoscopic cases were performed with the group reporting an overall complication rate of 11.9%. The rate was unchanged when the initial 20, 30 and 40 cases per surgeon were compared with all subsequent...
Combinatorial algorithms for DNA sequence assembly

The trend toward very large DNA sequencing projects, such as those being undertaken as part of the Human Genome Program, necessitates the development of efficient and precise algorithms for assembling a long DNA sequence from the fragments obtained by shotgun sequencing or other methods. The sequence reconstruction problem that we take as our formulation of DNA sequence assembly is a variation of the shortest common superstring problem, complicated by the presence of sequencing errors and reverse complements of fragments. Since the simpler superstring problem is NP-hard, any efficient reconstruction procedure must resort to heuristics. In this paper, however, a four-phase approach based on rigorous design criteria is presented, and has been found to be very accurate in practice. Our method is robust in the sense that it can accommodate high sequencing error rates, and list a series of alternate solutions in the event that several appear equally good. Moreover, it uses a limited form of multiple sequence alignment to detect, and often correct, errors in the data. Our combined algorithm has successfully reconstructed nonrepetitive sequences of length 50,000 sampled at error rates of as high as 10%.
Do American Football Helmets Protect Players Against Concussions

In recent years, reported concussions among American football players have attracted investigators attention as to the safety of the football helmet. This study investigates the effects of concussive impact forces on the brain of football players and the shock absorbing performance of actual football helmets. Initially, a lumped-mass analysis of the helmet and the head was carried out and then more detailed finite element models of the head and the helmet were analyzed. The results indicate that the acceleration and strain of the brain are both above the threshold of the concussion and that the current design of football helmet may not protect players against concussion.Copyright © 2013 by ASME
The adoption of ablation therapy for Barrett's esophagus: A cohort study of gastroenterologists

Abstract OBJECTIVES: Although ablation therapy may be useful in the treatment of Barrett’s esophagus, evidence of effectiveness is scarce, and little is known about current utilization of ablation. We aimed to determine whether the use of ablation was increasing in a cohort of gastroenterologists, and to identify physician beliefs and characteristics associated with ablation use. METHODS: We surveyed a national sample of gastroenterologists about ablation use, with an 18-month follow-up. The self-administered instrument included questions about demographic characteristics, attitudes about ablation therapy, and prior experience with ablation. Case scenarios were also included. We used logistic regression to identify factors associated with the use of ablation in patients with Barrett’s esophagus. RESULTS: Two hundred seventy-nine (50.3% of those eligible) responded to the baseline survey. Few agreed that ablation lowers the risk of adenocarcinoma (15%) or is supported by the medical literature (19%). However, 25% of respondents reportedly had used ablation at baseline, and this increased to 36% in the follow-up survey (p = 0.0003). The use of ablation was significantly associated with physician age greater than 54 yr (odds ratio [OR] = 2.77, 95% CI = 1.04–7.37) and the belief that ablation was used by colleagues (OR = 13.27, 95% CI = 4.44–39.64) or decreases medical costs (OR = 5.07, 95% CI = 1.00–25.74). CONCLUSIONS: Although few gastroenterologists agreed that ablation is effective, a significant proportion had adopted its use. There was a significant increase in ablation use during our study period, and the characteristic that was most strongly associated with ablation use was the belief that colleagues used it.
Antiandrogen Induced Cryptorchidism in the Pig is Associated with Failed Gubernacular Regression and Epididymal Malformations

AbstractPurpose: Can antiandrogens cause cryptorchidism in an animal model with a strip-like gubernaculum? If so, what anatomical abnormalities are associated with cryptorchidism?Materials and Methods: Timed pregnant sows received the antiandrogen flutamide during defined gestational intervals. Fetal pigs were evaluated for the presence of testicular undescent and for morphological paratesticular abnormalities at 110 days of gestation (birth).Results: Of 180 testes 84 (47 percent) were undescended and 9 (5 percent) were in the abdominal cavity. No undescended testis (0 of 200 testes) was found in control animals (p less than 0.001). Epididymal anomalies were found in all intra-abdominal testes, which was significant when compared to the epididymal abnormalities found with inguinal undescended testes (0 percent) or descended testes (1 percent) (p less than 0.001). Alterations in gubernacular morphology, in particular failure of gubernacular regression, were also directly associated with cryptorchidism (p l...
Neurobehavioral Functioning and Breastfeeding Behavior in the Newborn

Objective: To determine whether central nervous system functioning has an effect on the normal, term infant’s ability to breastfeed in the first day following birth. Design: Breastfeeding behaviors and neurobehaviors were evaluated at birth and at 24 hrs of age in two groups of neonates. One group of neonates was born to mothers who received epidural analgesia during labor, and one group was born to mothers who received no pain medication. Breastfeeding behavior was evaluated using the Preterm Infant Breastfeeding Behavior Scale, and the infant’s neurobehaviors were evaluated using the Neurologic and Adaptive Capacity Score. Participants: Fifty-six breastfeeding mother-newborn dyads. All mothers were healthy multiparae who gave birth vaginally to normal, full-term, healthy newborns. Main Outcome Measures: Newborns were observed for rooting, latch-on, sucking, swallowing, activity state, and neurobehavior. Result: Analysis of the data indicated that the higher the infant scored in relation to neurobehavioral functioning, the higher the infant scored on breastfeeding behaviors. Conclusion: When determining physiologically what is important for the infant to successfully latch on and feed, it appears that an intact and functioning central nervous system may be one of the crucial elements.
Diverse and dynamic sources and sinks in gradient formation and directed migration

The traditional view of directional cell migration within a tissue is that it requires a gradient of a soluble attractive chemical that is stable in space and time due to the presence of a source and a sink. However, advances in live imaging technology and the ability to study cell migration in vivo have revealed that endogenous sources and sinks are typically far more varied and complex. Both sources and sinks can be made up of multiple tissues. During long-range migrations, cells tend to divide up their trajectories and follow different source signals in each segment. When a single source signal is used repeatedly in each segment, its expression is dynamically controlled. Source signals can also originate locally from neighboring migrating cells. Sinks are important in some cases but not all, to sculpt a permissive migratory path or allow cells to move from one intermediate target to another. Migrating cells themselves can function as sinks to create a gradient out of an initially uniform chemoattractant. These diverse ways of building sources and sinks allow different cell types to navigate distinct trajectories through the same embryo even as the whole embryo undergoes the dramatic changes in cell number, position, arrangement and fate that are the essence of development.
Irradiation for Quarantine Control of the Invasive Light Brown Apple Moth (Lepidoptera: Tortricidae) and a Generic Dose for Tortricid Eggs and Larvae

The effects of irradiation on egg, larval, and pupal development, and adult reproduction in light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae),were examined. Eggs, neonates, third instars, fifth instars, and early stage pupae were irradiated at target doses of 60, 90, 120, or 150 Gy or left untreated as controls in replicated factorial experiments and survival to the adult stage was recorded. Tolerance to radiation generally increased with increasing age and developmental stage. A radiation dose of 120 Gy applied to eggs and neonates prevented adult emergence. A dose of 150 Gy prevented adult emergence in larvae at all stages. In large-scale validation tests, a radiation dose of 150 Gy applied to fifth instars in diet, apples or peppers resulted in no survival to the adult stage in 37,947 treated individuals. Pupae were more radio tolerant than larvae, and late stage pupae were more tolerant than early stage pupae. Radiation treatment of late pupae at 350 and 400 Gy resulted in three and one fertile eggs in 4,962 and 4,205 total eggs laid by 148 and 289 mating pairs, respectively. For most commodities, the fifth instar is the most radio tolerant life stage likely to occur with the commodity; a minimum radiation dose of 150 Gy will prevent adult emergence from this stage and meets the zero tolerance requirement for market access. For traded commodities such as table grapes that may contain E. postvittana pupae, a radiation dose > 400 Gy may be necessary to completely sterilize emerging adults. After review of the literature, a generic radiation treatment of 250 Gy is proposed for tortricid eggs and larvae in regulated commodities.
Migration of alumina grain boundaries containing a thin glass film

Bicrystals of alumina containing a glassy phase were produced by hot-pressing. Annealing the bicrystals at high temperatures (where a liquid forms at the boundary) can result in migration of the grain boundary. The migration of the boundary proceeds by the solution/reprecipitation mechanism. Many of the features of the migration closely resemble diffusion-induced grain-boundary migration but some important differences are identified.
Vasculogenic potential of porcine endothelial colony forming cells

The natural healing process cannot restore form and function to critical size bone defects without the presence of a graft to support and guide tissue regeneration [1]. Critical size bone defects in humans are typically on the order of centimeters or larger [2]. Thus, a major limitation of synthetic grafts or bone tissue engineering constructs is the lack of vascularization to support cell viability after placement in vivo [3]. Cells that participate in bone regeneration, must reside within 150–200 microns of a blood supply in order to gain proper nutrients and to eliminate waste [4]. Consequently, a tissue engineering construct of a clinically relevant size cannot rely on diffusion for transport of nutrients and waste. Previous research has shown that blood vessels can infiltrate scaffolds, but the overall process is too slow to prevent death of cells located in the center of a construct [5].Copyright © 2008 by ASME
Attributional Effects of Equal Employment Opportunity Theory Development at the Intersection of EEO Policy and Management Practice

The Americans With Disabilities and Rehabilitation Acts extend equal employment opportunity to categories that include those of individuals with seemingly self-inflicted and voluntary disabilities....
Survival Estimates for Patients with Abnormal Swallowing Studies

To better understand the life expectancy of patients who have an abnormal videofluoroscopic swallowing study. Retrospective cohort study. The common starting point was the time of the severely abnormal swallowing study. Hospital charts were reviewed for clinical variables of potential prognostic significance by reviewers blinded to the outcome of interest, survival time. A university-affiliated, community teaching hospital. One hundred forty-nine hospitalized patients who were deemed nonoral feeders based on their swallowing study. Patients excluded were those with head, neck, or esophageal cancer, or those undergoing a thoracotomy procedure. Clinical and demographic variables and time until death or censoring were measured. Overall 1-year mortality was 62%. Multivariable Cox proportional hazards analyses identified four variables that independently predicted death: advanced age, reduced serum albumin concentration, disorientation to person, and higher Charlson comorbidity score. Eighty patients (54%) subsequently underwent placement of a percutaneous endoscopic gastrostomy (PEG) tube after their swallowing study. Mortality is high in patients with severely abnormal swallowing studies. Common clinical variables can be used to identify groups of patients with particularly poor prognoses. This information may help guide discussions regarding possible PEG placement.
Smooth muscle myosin heavy chain and caldesmon expression in the anterior vaginal wall of women with and without pelvic organ prolapse

Abstract Objective: The aim of this study was to quantify the expression of smooth muscle myosin heavy chain (SM-MHC) and caldesmon in the anterior vaginal wall of women with and without pelvic organ prolapse. Study Design: Immunoblot analysis was conducted on protein extracts from the vaginal muscularis of 15 women with and 11 women without pelvic organ prolapse by using specific antibodies for SM-MHC, nonmuscle MHC-B, and caldesmon. The fraction of muscularis containing smooth muscle was determined by morphometric analysis of histologic cross sections. Reverse transcriptase–polymerase chain reaction was used to amplify SM-MHC isoforms produced by alternative splicing in the myosin head. Results: Whereas the expression of SM-MHC was increased modestly (2-fold), expression of smooth muscle caldesmon was increased 6- to 7-fold in vaginal muscularis from women with prolapse. The relative distribution of SM-MHC isoforms was similar in both groups. Conclusions: Caldesmon is increased substantially in vaginal smooth muscle of women with pelvic organ prolapse. Caldesmon inhibits actin-activated myosin magnesium adenosine triphosphatase activity and inhibits the maintenance of contractile force. Thus, this disproportionate increase in caldesmon, relative to myosin, may result in inhibition of vaginal smooth muscle contractility and force maintenance. (Am J Obstet Gynecol 2001;185: 944-52.)
Is Child Recruitment as a War Crime Part of Customary International Law

‘That it [the crime of non-forcible enlistment] exists for all present and future conflicts is declared for the first time by the judgments in this Court today’ were the words of Justice Robertson to mark the starting point of a new era in the development of international criminal law. On 20 June 2007, Trial Chamber II of the Special Court of Sierra Leone issued a historic decision convicting the three accused in the AFRC case on the count, among others, of ‘conscripting or enlisting children under the age of 15 years into armed forces or groups or using them to participate actively in hostilities’, constituting another serious violation of international humanitarian law pursuant to Article 4(c) of the Special Court Statute. This decision was not only historic for its content with regards to being the first endorsement by an international tribunal of the international criminalisation of the offence of child recruitment as contained in Article 4(c) of the Special Court Statute and in Articles 8(2)(b)(xxvi)...
Investigation of high-performance acid zinc nickel electrolyte

Abstract Zinc nickel alloy coatings are increasingly demanded by the automotive industry due to their highly improved corrosion protection over pure zinc and other zinc alloy coatings. To produce zinc nickel coatings with a nickel incorporation of 12 to 16%, mainly alkaline zinc nickel electrolytes are used in the plating industry. Continuous improvements in the field of acidic zinc nickel alloy electrolytes now meet the needs of the automotive industry while being advantageous in specific fields of application. In this paper, zinc nickel coatings deposited from alkaline as well as from ammonium-free acid zinc nickel electrolytes are investigated. The morphology is evaluated by scanning electron microscopy; the texture is investigated by focused ion beam, and X-ray diffraction patterns identify the structure of the coating. The corrosion protection of the zinc nickel coatings and the adhesion of the zinc nickel coatings have been bench-marked. For applications on fasteners, the coefficients of friction have been measured and compared.
On this, that, and the other: Nonegocentrism in very young children ☆

Abstract The development of comprehension and production of spatial deictic terms “this/that”, “here/there”, “my/your”, and “in front of/behind” was investigated in the context of a hide-and-seek game. The first three contrasts are produced according to the speaker's perspective, so comprehension requires a nonegocentric viewpoint. The contrast “in front of/behind” is produced relative to the hearer, i.e., production is nonegocentric. The subjects were 39 children, rangin in age from 2.5–4.5 years, and 18 college undergraduates. The 2.5-year-old children were best at those contrasts which do not require a shift in perspective. The 3- and 4-year-old children were adept at switching to the speaker's perspective for comprehension of the terms requiring this shift, i.e., were nonegocentric. Four-year-olds were also capable of nonegocentric production of “in front of/behind”.
Trypanosoma cruzi genome encodes a pteridine reductase 2 protein.

Pteridine metabolism in Trypanosoma cruzi is poorly understood. The term ‘pteridine’ is used collectively for two classes of structurally-related compounds, folates and biopterins, which differ only in the nature of the side chain attached to the C6 atom of the pterin ring. Both folate and biopterin, in their reduced (tetrahydro) forms, serve as essential cofactors in a number of critical metabolic steps in many organisms [1]. While some microorganisms and parasites such as Plasmodium can synthesize folate, mammals and trypanosomatid parasites lack this ability. On the other hand, mammalian cells can synthesize tetrahydrobiopterin de novo from GTP, while these parasites cannot synthesize biopterin either [2–4]. In order to meet the need for these essential nutrients, folate and biopterin are transported from the host into the parasite, and are subsequently reduced to their respective dihydro and tetrahydro forms by parasitic dihydrofolate reductase (DHFR) and pteridine reductase (PTR1) enzymes [1,2]. DHFR is one of the best characterized enzymes. Structure function relationships in DHFR from a variety of sources have been studied in detail and a number of inhibitors targeting DHFR has been successfully used in cancer chemotherapy and against some infectious pathogens including malaria parasite [1,5,6]. On the other hand, much of our current knowledge about pteridine reductase 1 (PTR1) is derived from research in Leishmania [7–12]. The Leishmania gene encoding PTR1 enzyme was found to be responsible for resistance to the classical antifolate drug methotrexate (MTX). The enzyme belongs to the family of short-chain dehydrogenases/reductases (SDR). Biochemical studies showed that it had broad substrate specificity and was able to reduce both folates and biopterins using NADPH as cofactor. PTR1 is considerably less sensitive (at
Theoretical Studies of Inorganic and Organometallic Reaction Mechanisms. 15. Catalytic Alkane Dehydrogenation by Iridium(III) Complexes

Alkane dehydrogenation catalyzed by the Ir(III) complexes (PCP‘)Ir(H)2 (1) [PCP‘ = η3-C6H3(CH2PH2)2-1,3] and CpIr(PH3)(H)+ (10) [Cp = η5-C5H5] is investigated with density functional theory (DFT). For both systems the theoretical results show that catalytic alkane dehydrogenation to alkene proceeds through (i) alkane oxidative addition, (ii) dihydride reductive elimination, (iii) β-H transfer from alkyl ligand to metal, and finally (iv) elimination of the olefin. Barriers for steps (i), (ii), and (iv) are critical for the catalytic cycle. The (PCP‘)Ir(H)2 system is special because these three barriers are balanced (16, 15, and 22 kcal/mol, respectively), whereas in the CpIr(PH3)(H)+ system these three barriers are unbalanced (9, 24, and 41 kcal/mol, respectively). Thus, in the catalytic cycle for alkane dehydrogenation by (PCP‘)Ir(H)2 the reaction endothermicity is achieved gradually. The higher stability of the formally Ir(V) complexes and the η2-alkene complex, which has some Ir(V)-like character, in th...
Density-functional calculations for III-V nitrides using the local-density approximation and the generalized gradient approximation

We have performed density-functional calculations for III-V nitrides using the pseudopotential plane-wave method where the d states of the Ga and In atoms are included as valence states. Results obtained using both the local-density approximation (LDA) and the generalized gradient approximation (GGA) for the exchange-correlation functional are compared. Bulk properties, including lattice constants, bulk moduli and derivatives, cohesive energies, and band structures are reported for AlN, GaN, and InN in zinc-blende and wurtzite structures. We also report calculations for some of the bulk phases of the constituent elements. The performance of our pseudopotentials and various convergence tests are discussed. We find that the GGA yields improved physical properties for bulk Al, ${\mathrm{N}}_{2},$ and bulk AlN compared to the LDA. For GaN and InN, essentially no improvement is found: the LDA exhibits overbinding, but the GGA shows a tendency for underbinding. The degree of underbinding and the overestimate of the lattice constant as obtained within the GGA increases on going from GaN to InN. Band structures are found to be very similar within the LDA and GGA. For the III-V nitrides, the GGA therefore does not offer any significant advantages; in particular, no improvement is found with respect to the band-gap problem.
ARRESTIN WITH A SINGLE AMINO ACID SUBSTITUTION QUENCHES LIGHT-ACTIVATED RHODOPSIN IN A PHOSPHORYLATION-INDEPENDENT FASHION

Arrestins are members of a superfamily of regulatory proteins that participate in the termination of G protein-mediated signal transduction. In the phototransduction cascade of vertebrate rods, which serves as a prototypical G protein-mediated signaling pathway, the binding of visual arrestin is stimulated by phosphorylation of the C-terminus of photoactivated rhodopsin (Rh*). Arrestin is very selective toward light-activated phosphorhodopsin (P-Rh*). Previously we reported that a single amino acid substitution in arrestin, Arg175Gln, results in a dramatic increase in arrestin binding to Rh* [Gurevich, V. V., & Benovic, J. L. (1995) J. Biol. Chem. 270, 6010-6016]. Here we demonstrate that a similar mutant, arrestin(R175E), binds to light-activated rhodopsin independent of phosphorylation. Arrestin(R175E) binds with high affinity not only to P-Rh* and Rh* but also to light-activated truncated rhodopsin in which the C-terminus phosphorylation sites have been proteolytically removed. In an in vitro assay that monitored rhodopsin-dependent activation of cGMP phosphodiesterase (PDE), wild type arrestin quenched PDE response only when ATP was present to support rhodopsin phosphorylation. In contrast, as little as 30 nM arrestin(R175E) effectively quenched PDE activation in the absence of ATP. Arrestin(R175E) had no effect when the lifetime of Rh* no longer contributed to the time course of PDE activity, suggesting that it disrupts signal transduction at the level of rhodopsin-transducin interaction.
Bombyxin exhibits an insulin-like response to modification in the N-terminal region of the A chain.

: Bombyxin is an insect neurohormone with an insulin-like structure. The N-terminal A chain helix, a region which is considered part of the active site in insulin, is almost identical between the two hormones. Bombyxin analogues with modifications at the N-terminus of the A-chain were synthesized and investigated for their ability to bind to bombyxin-specific receptors. While N-acetylation reduced the affinity to the bombyxin receptor to 18% the removal of glycine (A1) inactivated the hormone completely. Replacement of glycine (A1) by l-amino acids caused a significant loss in activity (11%) while its replacement by d-amino acid resulted in active bombyxin analogues (55%). Comparative CD spectroscopy indicated a change in structure for desGly(A1)bombyxin. Although the insect hormone does not have an insulin-like function it exhibits mammalian insulin-like structural sensitivity for A chain modifications.
Microbend pressure sensor for high-temperature environments

ABSTRACT Commercial multimode optical fibers, coated with aluminum, gold, or polyimide were used in apressure sensor that squeezed the fiber between a serrated disk and a compliant material. The sensor wastested up to 400F, and was found to perform well only in a uniform temperature environment. Differentialthennal expansion within the sensor made the sensor unusable in temperature transients. Preliminary testsshow that mode stripping before the photo-detector can improve the transient temperature response. 1.INTRODUCTION This study is a continuation of the work begun by Ferina et al who were developing a fast response pressure sensor for high temperature environments. They found that it is very difficult to designa microbend sensor for small pressure changes (0 - 5 psi), and that vibrational noise can be quite high for amicrobend sensor. In this study, the operating pressure range was raised to 100 psi so that the microbendforce could be increased, and the classical microbending arrangement of two rows of "teeth" squeezing ona fiber was replaced by a single row of serrations that squeezed the fiber against a compliant material. Thisarrangement was thought to be less vibration sensitive. The test facility was changed from the shock tubeused by Ferina, to the hydraulic oil facility described in this paper. This facility was not only easier to usebut also more repeatable than the shock tube.
High molecular weight fibrinogen derivatives in hyperlipidemia

Abstract Based on the finding of abnormal amounts of high molecular weight fibrinogen derivatives (HMWFD) in plasma, a process of continuous intravascular coagulation has been postulated to be present in hyperlipidemic patients. In order to determine whether these derivatives result from thrombin circulation in vivo, we studied the chromatographic profiles of fibrinogen and fibrinopeptide A (FPA) in plasma of type II hyperlipidemic patients and normal subjects. Fresh hyperlipidemic plasmas exhibited normal chromatograms. Freezing greatly enhanced the formation of HMWFD in comparison with normal. FPA levels were normal in all cases and did not correlate with HMWFD content of plasma. On the other hand a good correlation was observed between plasma cholesterol concentration and HMWFD in freezethawed samples. Our findings suggest that thrombin circulation in vivo is not likely to be responsible for the presence of HMWFD in hyperlipidemia but that, alternatively, LDL and/or other cholesterol transport proteins may play a significant role in the production of these derivatives in vitro when hyperlipidemic plasma is exposed to the cold.
What software engineering can learn from soccer

We've talked about software quality for a long time, developing numerous software quality assurance approaches in the hope of making our software increasingly better. Charles Mann, contributing editor of MIT's Technology Review, points out that other technologies-televisions, cars, airplanes, bridges-have improved over time as their engineering matured; he asks why software has not. In the February 2001 issue of Communications of the ACM, Edsger Dijkstra said that software's biggest challenge is "how not to make a mess of it." So, where have we gone wrong? To answer this question, we can look at how other disciplines learn and grow. Software development is as much an art as a science, and we learn lessons from both perspectives. Many of us think of ourselves as engineers: we train in engineering departments and rely on engineering tools, techniques, and quantitative methods to guide us. But our work's artistic side-which those who promote agile methods often emphasize-plays an important role, too. As good software developers, we are grounded in artistic engineering activities such as modeling and design. Our good people skills enable us to work with customers and on teams. And we need good instincts to select the best approaches and products to use.
Erythropoiesis stimulating agents approaches to modulate activity

Recombinant human erythropoietin (rHuEPO), such as the approved agents epoetin alfa and epoetin beta, has been used successfully for over 20 years to treat anemia in millions of patients. However, due to the relatively short half-life of the molecule (approximately 8 hours), frequent dosing may be required to achieve required hemoglobin levels. Therefore, a need was identified in some anemic patient populations for erythropoiesis stimulating agents with longer half-lives that required less frequent dosing. This need led to the development of second generation molecules which are modified versions of rHuEPO with improved pharma-cokinetic and pharmacodynamic properties such as darbepoetin alfa, a hyperglycosylated analog of rHuEPO, and pegzyrepoetin, a pegylated rHuEPO. Third generation molecules, such as peginesatide, which are peptide mimetics that have no sequence homology to rHuEPO have also recently been developed. The various molecular, pharmacokinetic, and pharmacodynamic properties of these and other erythropoiesis stimulating agents will be discussed in this review.
Genetic diversity-independent neutralization of pandemic viruses (e.g. HIV), potentially pandemic (e.g. H5N1 strain of influenza) and carcinogenic (e.g. HBV and HCV) viruses and possible agents of bioterrorism (variola) by enveloped virus neutralizing compounds (EVNCs)

Genetic diversity and hypermutation contribute to difficulties in developing a vaccine against viruses like HIV and influenza. There are currently no known immune correlates of protection against HIV. This has made the development of a vaccine against HIV that would provide sterilizing immunity in the near future an impossible task. The abandonment of a recent AIDS vaccine human trial due to a failure to elicit a protective sterilising immune response confirms that empirical attempts to develop a vaccine may result in failures. Also the difficulty in predicting the next pandemic strain of influenza may make it difficult to respond rapidly should there be an outbreak. Therefore, it is time to explore broad spectrum agents that can target either the lipid portion of the envelope or the sugar moieties of the glycoproteins or the rafts (regions within viral and cell envelopes where a higher concentration of the glycoproteins exist). Broad spectrum agents that can serve as disrafters or neutralize the viral infectivity by binding to the envelope lipid or sugar moieties will not be affected by the vagaries of hypermutation of surface antigens. This is because the post-translation modification is a host function. Presented here is a review of recently reported agents present in pomegranate juice (polyphenols, beta-sitosterol, sugars and ellagic acid) and fulvic acid, described here as the envelope virus neutralising compounds (EVNCs) and complex molecules like lectins and mucins. Pomegranate juice was previously reported to inactivate HIV and further shown by our group to inactivate influenza, herpes viruses and poxviruses. A formulation consisting of fulvic acid, a complex mixture of compounds was previously reported to render vaccinia virus, HIV and SARS virus non-infectious. Recently, both fulvic acid and pomegranate juice have been shown to inactivate genetically diverse strains of influenza including H5N1, further confirming the broad spectrum nature of these agents. How EVNCs will be used in developing a vaccine achieving sterilizing immunity or prophylaxis needs to be researched.
Grounding the cognitive neuroscience of semantics in linguistic theory

The mission of cognitive neuroscience is to represent the interaction of cognitive science and neuroscience: cognitive models of the mind guide a neuroscientific investigation of the brain bases of mental processes. In this endeavour, a cognitive model is crucial as without it, the cognitive neuroscientist does not know what to look for in the brain, what the nature of the relevant representations might be, or how the different components of a process might interact with each other. In the cognitive neuroscience of language, the interaction of theoretical models and brain research has, however, been far from ideal, especially when it comes to the study of meaning at the sentence level. Although theoretical semantics has a long history in linguistics and thus offers detailed and comprehensive models of the nature of semantic representations, these theories have had minimal impact on the brain investigation of semantic processing. In this article, we outline what a theoretically grounded cognitive neuroscie...
Effect of substrate temperature on the growth and luminescence properties of ZnO nanostructures

ZnO nanowires, nanorods and nanoribbons have been prepared by heating a mixture of ZnO/graphite powders using the thermal evaporation and vapor transport on Si(1 0 0) substrates without any catalyst. The nanostructures are grown as a function of substrate temperature ranging from 900 to 1300 K. These nanostructures are of the size 100–300 nm in diameter or width and several tens of micrometers in length. We studied the influence of the substrate temperature on the luminescent properties of these nanostructures. We observed a strong relationship between the substrate temperature and the green emission band in ZnO, i.e., the photoluminescence study revealed that the green emission peak of the ZnO nanostructures is suppressed relative to the band edge emission when the substrate temperature is decreased from 1300 to 900 K.
Light-induced disappearance of nitrite in the presence of iron (III).

Understanding of rapid disappearance of nitrite in natural waters and its impact on nitrogen natural cycling has remained limited. We found that NO−2 disappeared rapidly in pH 3.2 aqueous Fe(III) solutions both in sunlight and in 356 nm light. Quantum yields of the NO−2 loss at 356 nm were 0.049–0.14 for initial levels of 10–80 μm NO−2 and 200 μm Fe(III). The NO−2 loss (at 356 nm) followed apparent first-order kinetics. The rate constants were 1.3 × 10–3 (40 μm NO−2) and 4.1 × 10–4 s–1 (80 μm NO−2) for 100 μm Fe(III), and 2.3 × 10–3 (40 μm NO−2) and 7.5 × 10–4 s–1 (80 μm NO−12) for 200 μm Fe(III) (t1/2=8.7, 27.9, 5.1, and 15.3 min, respectively). The rate constants were directly proportional to [Fe(III)]0 and inversely proportional to [NO−2]0. Agreement between the rate constants obtained experimentally and those calculated mechanistically supports the hypothesis that NO−2 was oxidized to NO2 by radicals from photolysis of FeOH2+ complexes, and at high [NO−2]0 (e.g., 80 μm) relative to [Fe(III)]0, hydrolysis of NO2 or N2O4 to form NO−3 and NO−2 could be significant. This study showed that light and Fe(III)-induced oxidation of NO−2 (rate=∼10–1–10–2 μm s–1) was more rapid than its direct photolysis (rate= ∼10–4 μm s–1), and the photolysis could be a significant source of radicals only in cases where the Fe(III) level is much lower than the NO−2 level ([Fe(III)]/[NO−2] < 1/80). This study suggests that the light and Fe(III)-induced oxidation of NO−2 would be one potential important pathway responsible for the rapid transformation of NO−2 in acidic surface waters, especially those affected by acid-mine drainage or volcanic activities. This study also may be of interest for modeling certain acidic atmospheric water environments.
Optical residue arithmetic: a correlation approach

A numerical optical processor is described that performs operations in residue arithmetic. The position coding used to represent decimal and residue numbers allows one to describe the various conversions and operations in a correlation formulation. This description of residue arithmetic leads directly to novel residue adder and decimal/residue/decimal converter designs, which are described and experimentally demonstrated. The accuracy, dynamic range and space bandwidth of an optical residue arithmetic processor are also discussed.
The relationship between plateau burning behavior and ammonium perchlorate particle size in HTPB-AP composite propellants

Abstract The burning rates of series of bi- and trimodal AP-HTPB propellants have been incorporated into an empirical statistical model which describes a hypothetical pentamodal polydisperse AP pseudopropellant. This pseudopropellant is the linear summation of five unimodal polydisperse AP pseudopropellants. The five AP particle size distributions cover the range from 400 to 20 μm weight median diameter). The experimental propellants have been further subdivided into plateau burning and nonplateau burning propellants. The statistical model has been used to generate a plateau burning and a nonplateau burning pentamodal AP pseudopropellant. Plateau burning behavior in this propellant system (when compared to nonplateau burning behavior) appears to result from an enhanced burning rate at low pressures and a reduced burning rate at high pressures for the unimodal 20 μm AP pseudopropellant. It is speculated that such behavior is consistent with the presence of a binder melt on the burning surface. The larger AP unimodal pseudopropellants also show low burning rates and plateau burning behavior. Such behavior appears to be the result of variations in the importance of the AP monopropellant flame as a function of pressure and AP particle size. A melt layer on the AP particle surface during combustion may be the cause of the plateau burning behavior in the larger AP unimodal pseudopropellants. The temperature sensitivity of the unimodal pseudopropellants increases as a function of the AP particle size. Plateau burning behavior is maintained over the temperature range from 0° to 55°C.