cssi/SciSciGPT-SciSciNet huggingface dataset:
Exploiting rate-related hysteresis in repolarization alternans to improve risk stratification for ventricular tachycardia☆

Abstract OBJECTIVES We sought to study the effect of heart rate acceleration and deceleration on the ability of repolarization alternans (RPA) to stratify ventricular tachycardia (VT) risk. BACKGROUND Heart rate fluctuations alter arrhythmic propensity, yet it is unclear whether fluctuations, as well as absolute rate, dynamically increase VT risk. We hypothesized that repolarization heterogeneity reflected by RPA would exhibit hysteresis during rising and falling heart rate, which may reflect arrhythmic propensity. METHODS The RPA magnitude (absolute voltage of alternation [V alt ] and T-wave alternans ratio [TWAR]) and temporal distribution were determined from the electrocardiogram (ECG) in 60 patients during paced heart rate acceleration from 100 to 150 beats/min, then deceleration to 100 beats/min at electrophysiologic study (EPS). The V alt and TWAR thresholds were varied prospectively to generate receiver-operating characteristics (ROC) for the prediction of inducible VT at EPS. RESULTS Thirty-six patients were induced into VT and 24 were not. Hysteresis of RPA was seen. The V alt reached steady-state within 60 beats of each rate transition and was higher in deceleration than in acceleration at matched heart rates. In induced patients, V alt rose then fell with heart rate. In noninduced patients, V alt was insensitive to acceleration, but rose on initial deceleration. The RPA distributed later within repolarization in induced patients but, on deceleration, moved earlier in both groups. By ROC analysis, V alt = 2.6 μV in late repolarization at 120 beats/min provided optimal sensitivity and specificity for VT in acceleration (87.5% and 88.7%, respectively) versus deceleration (80% and 62.5%, respectively; p = 0.004, chi-square test). CONCLUSIONS 1) Physiologic fluctuations in heart rate may affect the clinical utility of RPA for VT risk stratification; and 2) repolarization dispersion measured by RPA is more exaggerated during deceleration than acceleration at matched heart rates (rate hysteresis).
Quasi-Classical Trajectory Modeling of OH Production in Direct Simulation Monte Carlo

The quasi-classical trajectory method enables one to obtain reaction probabilities and cross sections for fundamental reactions and to simulate strongly nonequilibrium flows. The formation of vibrationally hot OH for a rarefied flow about a sphere at 80- and 100-km altitudes are examined with the direct simulation Monte Carlo (DSMC) method. The main objective is to apply new chemistry models in the DSMC simulations of OH formation mechanisms in hypersonic flows at high altitudes. Using a numerically efficient parallel molecular dynamics (MD) code, we calculate the reaction cross sections and OH product rotational and vibrational distributions for two exchange reactions, H + O2 → → OH + O and O + H2 → OH + H. The reaction probabilities are then used in a DSMC computational tool to study OH production at 80- and 100-km altitudes. It is found that at 100 km the H + O2 exchange reaction is the main production mechanism of OH. Approximately an order of magnitude difference is observed for the MD and total collision energy rates, and differences in the predicted vibrational OH temperature were also obtained.
The Mask of Anarchy: The Destruction of Liberia and the Religious Dimension of an African Civil War, by Stephen Ellis (New York: New York University Press, 1999); Expectations of Modernity: Myths and Meanings of Urban Life on the Zambian Copperbelt, by James Ferguson (Berkeley and Los Angeles, University of California Press, 1999).

African studies, at least in its northern versions, has historically been about mediating Africa to the rest of the world. Those of us who teach in the United States are still stalked by battles from the 1960s about whether or not the study of Africa is intellectually viable; many of us claim that the real struggle is against stereotypes and correcting racist myths about Africa. Indeed, the syllabus for my undergraduate African history survey has in its introduction a few lines about how the stereotypes about nineteenth-century Africa—tribal warfare, superstition, poverty and disease—have hindered our ability to understand Africa's past and present. In their research, scholars have grappled—in varying degrees of course—with the question of how to represent Africa, and how to translate experience there to the rest of the world. Over the last forty years, this has meant some impressive apologies for repressive regimes and some imaginative accounts of social and economic conditions. If only one looked closely enough, many argued, one could see civil society/creative outpourings/new social arrangements emerging amidst growing poverty and disappointment. Such statements are anything but cynical, however: they are as much a part of the struggle against the older stereotypes as my upper division survey course claims to be. We are wary of showing an Africa that others might think awash with odd beliefs, or the site of meaningless violence, or as having politics that are more corrupt than consensual. Besides, what we study in Africa has been the subject of much criticism within the field, and many scholars also struggle against claims that we are exoticizing Africa, or, as in a famous critique of a Rhodes-Livingstone Institute anthropologist (see Ferguson, 28–29), that we study what is irrelevant to African lives—like leisure—instead of the colonial oppression under which Africans toiled. Many scholars have taken this critique quite seriously, and have approached the study of African songs, gossip, and sexuality with some defensiveness; others have focused on colonialism and its myriad evils to the point that independent Africa (i.e., the last thirty to forty years) is rarely an object of study in and of itself, but instead is the direct result of colonialism (i.e., the colonial legacy). The result has been at best linear, and at worst paternalistic. How Africans understand their own contemporary dilemmas has rarely been an object of enquiry.
An examination of the effects of self-rated and objective indicators of health condition and economic condition on the loneliness of older persons

Examined is the experience of loneliness as it relates to selected health conditions and selected economic conditions. The effects on loneliness of age, gender, marital status, number of sons, number of daughters, number of male friends, and number of female friends also were examined and controlled. Results are based on a sample from the Senior Citizens Nutrition and Activities Program in Hillsborough County, Florida. An analysis of covariance showed that greater loneliness was expressed by those older persons who were male, had fewer female friends, and had fewer male friends. Among the main effects, poorer self-rated health, less adequate self-rated economic condition, and being in poverty were related to greater loneliness. The interactions between the main effects variable were unrelated to loneliness. The research sheds new light on the influence on loneliness of older persons' health and economic condition, and of selected demographic and interpersonal relationship variables.
Polyglactin 910 suture in urinary tract

Cystotomies in guinea pigs and ureteral anastomoses in dogs were sutured with polyglactin 910. Silk and chromic catgut were used as control sutures in the bladders and chromic catgut in the ureters. Three months postoperatively in bladders sutured with polyglactin 910 small epithelial cysts were noted, which increased in size with time. In ureters sutured with polyglactin 910 cystic diverticula were observed eight months postoperatively. Because of the difference of tissue reaction to polyglactin 910 compared with catgut, further long-term studies are urged in different species of animals, prior to the clinical use of polyglactin 910 in the urinary tract.
The Dynamics of International Legal Regime Formation: The Sino-British Joint Declaration on the Question of Hong Kong Revisited

The academic literature on the systems that govern relations between states is rich but not without gaps. The subject of international legal regime formation is one that may benefit from further exploration. The protracted and unnerving process leading to the signing of a path-breaking agreement between China and the United Kingdom regarding the future of Hong Kong, a topic which has fascinated historians but has not galvanized socio-legal researchers into action on a meaningful scale, may offer considerable insights pertaining to the development of governance systems that regulate complex interaction between states.
Ketamine relaxes rabbit femoral arteries by reducing [Ca2+]i and phospholipase C activity

The effects of the short-acting anesthetic, ketamine, on intracellular free Ca2+ concentrations, ([Ca2+]i), inositol phosphate levels and force produced by contractile agonists were investigated in strips of rabbit femoral artery. In concentration-response curves, ketamine produced an insurmountable inhibition of contractions produced by KCl and the L-type Ca2+ channel agonist, Bay k 8644. However, in K(+)-depolarized tissues, high concentrations of CaCl2 could overcome the inhibition produced by ketamine, suggesting that ketamine may have competed with Ca2+ in activated L-type Ca2+ channels. In support of the contention that it inhibits L-type Ca2+ channels, ketamine was found to concomitantly reduce the levels of force and [Ca2+]i produced by 50 mM KCl. Ketamine reduced the potency, but not the maximum force, produced by phenylephrine. However, this surmountable inhibition may have been due to activation of 'spare' alpha-adrenoceptors rather than to competition of receptor binding because, after phenoxybenzamine pretreatment to reduce alpha-adrenoceptor numbers, phenylephrine concentration-response curves in the presence of ketamine were insurmountable. Ketamine at 0.32 mM reduced the transient contractions produced in a Ca(2+)-free solution and the increase in phospholipase C activity (estimated by measuring inositol phosphate production in the presence of Li+) produced by 1 but not 10 microM phenylephrine. These data suggest that ketamine inhibited contractions produced in rabbit femoral artery by decreasing Ca2+ channel activity and by reducing phospholipase C activation.
Gender as a context for interpreting the self‐directed learning experiences of prostate and breast cancer patients

This article reports the findings from a secondary analysis of the data from two qualitative studies conducted by the researcher regarding the self‐directed learning experiences of prostate and breast cancer patients. Of interest were possible differences in the descriptions of the participants’ experiences that appear to relate to gender. Semi‐structured interviews were conducted with 12 prostate cancer patients and 13 breast cancer patients. The resulting transcripts were analyzed using the constant comparative method. The same research process, geographic location and interview protocol were used for both studies. Differences that appear to relate to gender were found in regard to privacy, seeking connections, handling emotions, and perspectives on the personal impact of their self‐directed and cancer experiences.
The Developmental Role of warthog, the Notch Modifier Encoding Drab6

The warthog (wrt) gene, recovered as a modifier for Notch signaling, was found to encode the Drosophila homologue of rab6, Drab6. Vertebrate and yeast homologues of this protein have been shown to regulate Golgi network to TGN trafficking. To study the function of this protein in the development of a multicellular organism, we analyzed three different warthog mutants. The first was an R62C point mutation, the second a genomic null, and the third was an engineered GTP-bound form. Our studies show, contrary to yeast, that the Drosophila homologue of rab6 is an essential gene. However, it has limited effects on development beyond the larval stage. Only the mechanosensory bristles on the head, notum, and scutellum are affected by warthog mutations. We present models for the modifying effect of Drab6 on Notch signaling.
Diffusion of ladder-type innovations: a study of computer and communications convergence

Abstract Computer technology, virtually non-existent five decades ago, has diffused rapidly since its inception and is now of major strategic importance. Since its introduction there has been a steady acceleration of the innovation process in the computer industry and this has significantly impacted the market adoption of computer systems. An important innovation in the computer industry is its fusion with the communications technology. This convergence of telecommunications and computers is considered a major revolution which has helped to create new market segments for the computer industry. In this study we model this convergence as a ladder-type innovation and develop a diffusion model to study its impact on the market demand by the computer user community. The empirical analysis suggests significant impact of communications technology on the demand for computer systems. © 1997 Elsevier Science Ltd
Initial Treatment of Glaucoma: Surgery or Medications

Should surgery or medications be the initial therapy for primary open angle glaucoma? In this set of articles, Drs. Sherwood, Migdal, and Hitchings present evidence suggesting that filtration surgery provides better intraocular pressure control than does medical treatment, good (or better) visual field preservation, and visual acuity as good as that in medically treated fellow eyes. They also cite cost effectiveness, quality of life, and possible adverse effects of medical treatment on future surgery. Drs. Sharir and Zimmerman, on the other hand, favor initial medical therapy, questioning the validity of some reports on surgical results, citing the risks of complications, and noting recent and current progress in the development of antiglaucoma medications. Dr. Schultz' editorial evaluates both points of view, concluding that additional prospective randomized tests may be useful and that either approach may be a viable option, as long as it is individualized to each particular patient.
Tetralogy of fallot with left ventricular hypertrophy

Summary 1. A case is presented of tetralogyof Fallot with left ventricular hypertrophy. 2. Several exceptional cases are presented of anomalies in the cyanotic group, other than tricuspid atresia, which show left ventricular hypertrophy. 3. The importance of unipolar electrocardiographyis stresed.
Piezoelectric Damping of Resistively Shunted Beams and Optimal Parameters for Maximum Damping

This paper studies the piezoelectric damping of resistively shunted beams induced by the conversion of the vibration energy into electrical energy that is dissipated in the resistor through Joule heating. Significant contributions have been made in the modeling and development of the resistive shunt damping technique; however, many approaches involve complex models that require the use of numerical methods to determine system parameters and predict damping. This paper develops a closed-form solution for the optimal parameter of a resistive shunt damping system. The model is validated through experimental testing and provides a simple yet accurate method to predict the induced damping in a smart structure.
The distribution of acteoside among angiosperms

Abstract The distribution of the phenylpropanoid glycoside acteoside is restricted to a constellation of families which may constitute a natural ordinal grouping. This distribution of acteoside contains many families traditionally clustered in a Scrophulariales-Lamiales complex. It includes Retziaceae, Oleaceae, Stilbaceae, and Hippuridaceae, but excludes Hydrostachyaceae.
Leukapheresis in the treatment of Sézary syndrome

Abstract Five patients received leukapheresis therapy for Sezary syndrome. All patients had erythroderma, lymphocytic band infiltration of the skin, and a normal white blood cell count with an absolute Sezary cell count of more than 1,000/mm 3 . Improvement in 3 to 6 months occurred, usually with the addition of a combined regimen of prednisone and low-dose chlorambucil therapy. One patient had sustained improvement with repeated leukapheresis for more than 2 years. The two patients who showed a major response were the youngest patients, who had normal karyotypes, normal delayed-hypersensitivity skin tests, and a quantitative response of the Sezary cells and the T and B cells to leukapheresis. These preliminary results suggest that there may be selected patients for whom leukapheresis is useful therapy and that it is possible to perform the procedure safely in patients with normal white blood cell counts.
Improved kernel security through memory layout randomization

The vast majority of hosts on the Internet, including mobile clients, are running on one of three major operating system families. Malicious operating system kernel software, such as the code introduced by a kernel rootkit, is strongly dependent on the organization of the victim operating system. Due to the lack of diversity of operating systems, attackers can craft a single kernel exploit that has the potential to infect millions of hosts. If the underlying structure of vulnerable operating system components has been changed, in an unpredictable manner, then attackers must create many unique variations of their exploit to attack vulnerable systems en masse. If enough variants of the vulnerable software exist, then mass exploitation is much more difficult to achieve. Many forms of automatic software diversification have been explored and found to be useful for preventing malware infection. Forrest et. al. make a strong case for software diversity and describe a few possible techniques including: adding or removing nonfunctional code, reordering code, and reordering memory layouts. Our techniques build on the latter. We describe two different ways to mutate an operating system kernel using memory layout randomization to resist kernel-based attacks. We introduce a new method for randomizing the stack layout of function arguments. Additionally, we refine a previous technique for record layout randomization by introducing a static analysis technique for determining the randomizability of a record. We developed prototypes of our techniques using the plugin architecture offered by GCC. To test the security benefits our techniques, we randomized multiple Linux kernels using our compiler plugins. We attacked the randomized kernels using multiple kernel rootkits. We show that by strategically selecting just a few components for randomization, our techniques prevent kernel rootkit infection.
Extrinsic origins of the somatostatin and neuropeptide Y innervation of the rat basolateral amygdala.

The amygdalar basolateral nuclear complex (BLC) is a cortex-like structure that receives inputs from many cortical areas. It has long been assumed that cortico-amygdalar projections, as well as inter-areal intracortical connections, arise from cortical pyramidal cells. However, recent studies have shown that GABAergic long-range nonpyramidal neurons (LRNP neurons) in the cortex also contribute to inter-areal connections. The present study combined Fluorogold (FG) retrograde tract tracing with immunohistochemistry for cortical nonpyramidal neuronal markers to determine if cortical LRNP neurons project to the BLC in the rat. Injections of FG into the BLC produced widespread retrograde labeling in the cerebral hemispheres and diencephalon. Triple-labeling for FG, somatostatin (SOM), and neuropeptide Y (NPY) revealed a small number of FG+/SOM+/NPY+ neurons and FG+/SOM+/NPY− neurons in the lateral entorhinal area, amygdalopiriform transition area, and piriform cortex, but not in the prefrontal and insular cortices, or in the diencephalon. In addition, FG+/SOM+/NPY+ neurons were observed in the amygdalostriatal transition area and in a zone surrounding the intercalated nuclei. About half of the SOM+ neurons in the lateral entorhinal area labeled by FG were GABA+. FG+ neurons containing parvalbumin were only seen in the basal forebrain, and no FG+ neurons containing vasoactive intestinal peptide were observed in any brain region. Since LRNP neurons involved in corticocortical connections are critical for synchronous oscillations that allow temporal coordination between distant cortical regions, the LRNP neurons identified in this study may play a role in the synchronous oscillations of the BLC and hippocampal region that are involved in the retrieval of fear memories.
Pharmacologic options for aggressive low-density lipoprotein cholesterol lowering: benefits versus risks.

Lessons from recent end point trials of lipid-lowering drugs indicate that patients at very high risk for coronary artery disease (CAD) benefit from treatment that lowers low-density lipoprotein (LDL) cholesterol plasma levels to ≤1.81 mmol/L (≤70 mg/dL), that patients with ≥2 risk factors benefit from treatment that lowers plasma LDL cholesterol to
Measuring the interestingness of articles in a limited user environment

Search engines, such as Google, assign scores to news articles based on their relevance to a query. However, not all relevant articles for the query may be interesting to a user. For example, if the article is old or yields little new information, the article would be uninteresting. Relevance scores do not take into account what makes an article interesting, which would vary from user to user. Although methods such as collaborative filtering have been shown to be effective in recommendation systems, in a limited user environment, there are not enough users that would make collaborative filtering effective. A general framework, called iScore, is presented for defining and measuring the ''interestingness'' of articles, incorporating user-feedback. iScore addresses the various aspects of what makes an article interesting, such as topic relevance, uniqueness, freshness, source reputation, and writing style. It employs various methods, such as multiple topic tracking, online parameter selection, language models, clustering, sentiment analysis, and phrase extraction to measure these features. Due to varying reasons that users hold about why an article is interesting, an online feature selection method in nai@?ve Bayes is also used to improve recommendation results. iScore can outperform traditional IR techniques by as much as 50.7%. iScore and its components are evaluated in the news recommendation task using three datasets from Yahoo! News, actual users, and Digg.
Colonic pseudo-obstruction in surgical patients.

Summary Colonic pseudo-obstruction (Ogilvie's syndrome) may occur in surgical patients, particularly those who have had orthopedic or blunt trauma, have uremia or diabetes, have complex metabolic or cardiac failure, have metastatic cancer involving the lymph nodes and neural tissue, or are addicted to narcotics. Although a single true cause has not been identified by fulfilling Koch's postulates, the clinical pattern has been recognized in a variety of surgical patients, and this pattern must be distinguished from true obstruction of the colon. Tumor or internal hernia may constitute an obstruction, but the important differential diagnosis of cecal volvulus must be excluded. Ischemic colitis may be confused with Ogilvie's syndrome or may follow it. Gangrene, infarction, and perforation may ensue as colon diameter increases and particularly if cecal distention reaches above 14 cm. This arbitrary number for cecal dilatation should not be awaited before treatment is instituted if signs of devitalization of the gut or peritoneal signs have developed in the patient. Treatment has changed recently with the wide-spread application of colonoscopy. Endoscopy is helpful in relieving distention but may also be dangerous in the patient with a massively distended colon, particularly at the level of the thin-walled cecum. Colonoscopy also appears to be associated with a high rate of treatment failure and recurrence. Surgical decompression may take the form of cecostomy or may require exteriorization or resection of the colon if infarction has occurred. A series of 12 patients has been presented. The patients were all referred to a single surgeon in a university medical center over a 4½ year period with clinical patterns not suggestive of a common cause but a similar clinical evolution of Ogilvie's syndrome. The prognosis for such patients in whom the complication is recognized early and in whom decompression is performed endoscopically or surgically is encouraging. If recognition is late and particularly if perforation and gangrene result, mortality is nearly 50 percent.
Head-mounted electrode platform: Construction and error analysis

Abstract A technique is described for constructing an electrode guidance platform which is mounted on the animal's head. An analysis of error for 246 electrodes in 14 animals is described and indicates use of the technique does not degrade stereotactic accuracy.
Georg Simmel and the Aesthetics of Social Reality

Georg Simmel's sociology is shown to be grounded on his aesthetics. Isomorphisms between his sociological and aesthetic approaches to their respective subject matters are found in their similar stress on (1) the visual modality, (2) the separation of the product from the process which created it, and (3) the method of generalization through particularization. Although Simmel's sociology is usually said to be disorganized, considering his sociology to be modeled after his aesthetics reveals that it is actually more unified in conception than is commonly thought. Arthur Salz (1959) once said he learned from his teacher Georg Simmel, the following about society: "[Simmel] conceives of sociology as the study of the forms of sociation. But whoever speaks of forms moves in the field of aesthetics. Society, in the last analysis, is a
Post-robotic prostatectomy urinary continence: characterization of perfect continence versus occasional dribbling in pad-free men.

Objectives To review and characterize two groups of men who report being pad-free after robot-assisted laparoscopic prostatectomy (RLRP): those with occasional incontinence and those with complete control. Methods The study included 106 out of a total of 195 men who underwent RLRP. Inclusion requirements were adequate follow-up and no-pad continence status. All patients completed self-administered American Urological Association symptom score (AUAss) and continence questionnaires and underwent measurement of peak urinary flow rates, postvoid residual volumes, and voided volumes (VV) before and 3 months after surgery. All data and standard clinical characteristics were entered prospectively into an electronic database. Results Two distinct groups reported wearing no pads: the “perfect” group (n = 32) reported never leaking, and the “imperfect” group (n = 74) reported occasional leakage but did not wear pads. Preoperatively, the “imperfect” group was older (62.2 versus 59 years) and had more urinary symptoms (all P <0.05). Postoperatively, the “imperfect” group took longer to achieve a pad-free status (median 39.8 versus 19.3 days), had larger prostates (mean 50.9 versus 43.2 g), had lower VV (324 versus 405 mL), and more urinary symptoms (AUAss 7.4 versus 4.3; all P <0.05). Conclusions Sixty-nine percent of men who attain “pad-free continence” after RLRP have occasional urinary leakage. Preoperatively, these men are characteristically older and have larger prostates, AUAss, and bother scores. Postoperatively, the “imperfect” group takes longer to achieve pad-free status and has smaller bladder capacities and more urinary symptoms. These results suggest that an overactive detrusor is the likely contributing etiology.
ASSESSING THE IMPACT OF READING GOALS AND TEXT STRUCTURES ON COMPREHENSION

The present study examined the unique contributions of readers' goal and text structure on comprehension. In Experiment 1, participants read procedural and descriptive passages to perform the procedures, summarize the passages, or to answer questions. The perform goal showed highest comprehension, with no difference due to text type. In Experiment 2, participants read either a narrative-like or a list-like procedural text. The narrative-like text led to better comprehension than the list-like text for the perform condition, but this finding was reversed for the other conditions. The results indicate that past differences on text type were based on differences on local coherence.
Promoting a Consumer Orientation to Health Care and Health Promotion

There is a compelling need to establish a consumer orientation to health care to address the troubling imbalance of power between providers and consumers in the modem health-care system. This power imbalance has systematically disenfranchised and marginalized health-care consumers. Adoption of a consumer orientation that focuses institutional attention and resources specifically on fulfilling the physical and psychological needs of the consumer, equalizing influence and control between health-care providers and consumers, and empowering consumers to make informed decisions about their health care will help promote social justice within the modem health-care system. Strategies are suggested to help providers and consumers develop and promote a consumer orientation in modem health care.
Interplay of C1 and C2 Domains of Protein Kinase C-α in Its Membrane Binding and Activation

The regulatory domain of conventional protein kinase C (PKC) contains two membrane-targeting modules, the C2 domain that is responsible for Ca2+-dependent membrane binding of protein, and the C1 domain composed of two cysteine-rich zinc fingers (C1a and C1b) that bind diacylglycerols and phorbol esters. To understand the individual roles and the interplay of the C1 and C2 domains in the membrane binding and activation of PKC, we functionally expressed isolated C1 and C2 domains of PKC-α and measured their vesicle binding and monolayer penetration. Results indicate that the C2 domain of PKC-α is responsible for the initial Ca2+- and phosphatidylserine-dependent electrostatic membrane binding of PKC-α, whereas the C1 domain is involved in subsequent membrane penetration and diacylglycerol binding, which eventually lead to enzyme activation. To determine the roles of individual zinc fingers in the C1 domain, we also mutated hydrophobic residues in the C1a (Trp58 and Phe60) and C1b (Tyr123 and Leu125) domains of the native PKC-α molecule and measured the effects of mutations on vesicle binding, enzyme activity and monolayer penetration. Results show that the hydrophobic residues in the C1a domain are essential for the membrane penetration and activation of PKC-α, whereas those in the C1b domain are not directly involved in these processes. Based on these results in conjunction with our previous structure-function studies of the C2 domain (Medkova, M., and Cho, W. (1998) J. Biol. Chem. 273, 17544–17552), we propose a mechanism for the in vitro membrane binding and activation of conventional PKC that accounts for the temporal and spatial sequences of PKC activation.
F and F+ luminescence in thermochemically reduced MgO crystals☆

The predominance of F over F+ luminescence in thermochemically reduced MgO crystals is caused by H-ions. The electron traps responsible for the thermoluminescence peaks 100 and 260 K are discussed.
Evolutionary palaeoecology of early epifaunal echinoderms: Response to increasing bioturbation levels during the Cambrian radiation

Abstract Increasing bioturbation depth and intensity during the Cambrian radiation created a transition in dominant subtidal soft substrates from firm Proterozoic-style soft substrates without a well-developed mixed layer to soupier Phanerozoic-style soft substrates with a well-developed mixed layer. Microbial mats were also relegated to settings with inhibited metazoan activity but made resurgences during later ecological crises. Previous work suggests that this substrate change strongly influenced the evolution of Cambrian benthic suspension-feeding echinoderms. In order to test this previous work and reveal longer-term evolutionary patterns, the substrate adaptations of 93 genera in the three classes of benthic suspension-feeding echinoderms with definitive Cambrian origins (edrioasteroids, eocrinoids, and helicoplacoids) were examined throughout their fossil records. This examination reveals that genera adapted to typical Proterozoic-style soft substrates were taxonomically dominant during, and were almost entirely restricted to, the Early and Middle Cambrian. Thereafter, from the Late Cambrian through the Carboniferous, genera adapted to typical Phanerozoic-style soft substrates were taxonomically dominant. This trend supports previous studies and defines a fundamental evolutionary shift in echinoderm substrate interactions in response to increased mixed layer development during the Cambrian radiation. A notable exception to this trend is the Late Devonian edrioasteroid Cooperidiscus , which is morphologically convergent with the Early and Middle Cambrian sediment-attaching edrioasteroid Stromatocystites . This convergence is likely the result of Cooperidiscus adapting as a sediment attacher to typical Proterozoic-style soft substrates that developed during or shortly after the Late Devonian mass extinction. This study indicates for the first time that adaptation to non-actualistic substrates during ecological crises can result in morphological convergence with forms adapted to similar substrates common during the Cambrian radiation.
A dynamic-flow carbon-cycle box model and high-latitude sensitivity

Most of the hypotheses put forward to explain glacial–interglacial cycles in atmospheric pCO 2 are centred on Southern-Ocean-based mechanisms. This is in large part because: (1) timing constraints rule out changes in the North Atlantic as the trigger; (2) the concept of “high-latitude sensitivity” eliminates changes in the non-polar oceans as likely contenders. Many of the Southern-Ocean-based mechanisms for changing atmospheric pCO 2 on glacial–interglacial time-scales are based on results from highly simplified box models with prescribed flow fields and fixed particulate flux. It has been argued that box models are significantly more “high-latitude sensitive” than General Circulation Models. In light of this, it is important to understand whether this high-latitude sensitivity is a feature common to all box models, and whether the apparent degree of sensitivity changes for different tracers and parameters. We introduce a new metric for assessing how “high-latitude sensitive” a particular solution is to perturbations. With this metric, we demonstrate that a given model may be high-latitude sensitive to certain parameters but not to others. We find that the incorporation of a dynamic-based flow field and a Michaelis–Menten type nutrient feedback can have a significant impact on the apparent sensitivity of the model to perturbations. The implications of this for current box-model-based estimates of atmospheric pCO 2 drawdown are discussed. DOI: 10.1111/j.1600-0889.2006.00192.x
Quadratic semigroups on affine spaces

Abstract As a generalization of some aspects of the theories of algebraic groups and finite dimensional algebras one can study polynomially defined, associative operations on affine spaces. In this paper we study the quadratic case—i.e., the case when the polynomials are of degree at most two. We call the resulting semigroup a quadratic semigroup. We obtain the complete structure for one class of quadratic semigroups and a representation theorem for another class.
CLEISTOGAMY IN SALPIGLOSSIS SINUATA

Cleistogamy in Salpiglossis sinuata L. (Solanaceae) involves a series of developmental events that includes germination of pollen tetrads en masse inside the anther, penetration of pollen tubes through the anther wall toward the stigma which is in contact with the anther, growth of pollen tubes down the style, and, finally, fertilization. This occurs within 6 days from the first appearance of the flower as compared to 10-12 days for normal anthesis of chasmogamous flowers. Coincident with these events in cleistogamous flowers are lack of corolla development and reduced size of androecium and gynoecium. SALPIGLOSSIS SINUATA (common name: velvet flower or painted tongue) is an annual plant cultivated as an ornamental. The genus Salpiglossis (Solanaceae) contains 10 species from South America (Werderman, 1928); S. sinuata is the only cultivated species. Cleistogamy in S. sinuata was first reported by Vilmorin (1894) who described such flowers without corolla, with short pistil, and with the capability of producing numerous seeds. Savelli later noticed (1927) that the expression of cleistogamy in Salpiglossis species was unstable and referred to this condition as "pseudo-cleistogamy."
Response of the interatrial septum to transatrial pressure gradients and its potential for predicting pulmonary capillary wedge pressure: An intraoperative study using transesophageal echocardiography in patients during mechanical ventilation

Abstract Objectives . We hypothesized that the directional movement of the interatrial septum and its curvature may reflect the pressure relations between the left and right atria. Background . Interventricular septal shape is primarily dependent on the pressure gradient between the left and the right ventricle. No analogous study has carefully evaluated the determinants of interatrial septum shape and motion. Methods . Patients (n = 52) undergoing cardiac or vascular surgery were studied intraoperatively at multiple intervals with transesophageal echocardiography and simultaneous measurement of central venous pressure, pulmonary capillary wedge pressure and airway pressure. Results . Overall interatrial septum shape, which usually curved toward the right atrium, changed concordantly with the interatrial pressure gradient (pulmonary capillary wedge pressure-central venous pressure difference). The degree of interatrial septum curvature was also primarily dependent on the interatrial pressure gradient and, to a lesser extent, was affected by changes in left atrial size (F = 130.4 vs. F = 14.1). During passive mechanical expiration, the interatrial pressure gradient, usually positive, often reverses transiently and the interatrial septum momentarily bows toward the left atrium. Midsystolic reversal was seen in 64 of 72 episodes when the pulmonary capillary wedge pressure was ≤15 mm Hg but in only 2 of 40 episodes when it was >15 mm Hg (sensitivity = 0.89, specificity = 0.95, positive predictive value = 0.97). Conclusions . These findings suggest that overall interatrial septum shape depends on the pressure gradient between the left and right atria. Midsystolic reversal of the interatrial septum, which probably reflects the increased venous return in the right relative to the left atrium during mechanical expiration, may be a useful indicator of the pulmonary capillary wedge pressure.
Computed Tomography of the Heart and Great Vessels: Present and Future

Computed tomography (CT) has emerged as a new imaging method for the diagnosis and evaluation of cardiovascular disease. With CT body scanners and contrast enhancement, evaluation of aortic dissections and aneurysms, coronary bypass graft patency, cardiovascular thrombus, cardiac tumors, and pericardial disease is possible. On occasion, this technique provides clinically useful information that is not available with other imaging methods. Electrocardiographic gating retrospectively or prospectively improves the image resolution of CT scans, but a new ultrafast CT scanner with a scan time of 30 to 50 milliseconds offers the greatest promise for expanding the application of the technology for cardiovascular diagnosis. Accurate measurement of cardiac chamber volume, mass, wall motion, and wall thickening will be feasible. Ultrafast CT scanning also shows great promise for the measurement of myocardial infarct size and regional myocardial blood flow.
Studies on the metabolism of ATP by isolated bacterial membranes: role of succinyl CoA synthetase in diglyceride kinase activity.

Abstract The diglyceride kinase activity of isolated E. coli membrane vesicles appears to be mediated in part by succinyl CoA synthetase. Upon incubation of vesicles with [γ- 32 P]ATP, or with 32 P i and succinyl CoA, radioactivity appears in membrane-bound phosphatidic acid. CoA inhibits incorporation of radioactivity from [γ- 32 P]ATP. Succinate lowers the concentration of CoA required to inhibit this incorporation, although succinate alone stimulates incorporation. At high [γ- 32 P]ATP concentrations, inhibition by succinate and CoA is overcome. The results suggest that diglyceride kinase can use either ATP or the phosphorylated form of succinyl CoA synthetase as phosphate donor for the phosphorylation of diglyceride.
A Comparison of Fast Neutron Irradiation Effects in Photoconductive and Photovoltaic InSb Infrared Detectors

The relative neutron irradiation hardness of photoconductive and photovoltaic InSb infrared detectors is examined for various operating modes and conditions. It is found that photoconductors are much less vulnerable to fast neutrons at 78K than are photovoltaic detectors. The damage mechanisms for photovoltaic detectors are increased leakage currents coupled with a decrease of minority carrier lifetime in the bulk region with a damage constant of 1.5 × 10-14 ?m-2 n-1 cm2, while a carrier removal rate of 1.1 cm-1 is established for 14 MeV neutron-irradiated p-type InSb with an initial carrier concentration of ~3 × 1014 cm-3. It is shown that these changes in material parameters can be used to predict fast neutron damage under all realistic operating conditions. The effects of neutron irradiations on signal, noise, current-voltage characteristics and spectral response are discussed in detail.
Projecting Agricultural Productivity and Its Economic Impact

Public investment in U.S. agricultural research and extension (R&E) programs, mostly by the USDA and state agriculture experiment, stations, increased rapidly in recent decades. Expenditures oriented to increasing agricultural production increased from $149 million in 1939 to $377 million in 1972 (1958 dollars). But with such visible signs as Proposition 13 in California to zero-based budgeting at the national level, both public and private decision makers are demanding greater accountability for, and productivity from, burdensome tax dollars.
Enantioselective synthesis of (-)-pentalenene.

A short, enantioselective synthesis of (−)-pentalenene is described. Catalytic enantioselective cyclopropenation with (R,R)-Rh2(OAc)(DPTI)3 was used to set the absolute stereochemistry, and an intramolecular Pauson−Khand reaction of the resulting cyclopropenyne was used to establish the quaternary center.
User acceptance of information technology: system characteristics, user perceptions and behavioral impacts

Abstract Lack of user acceptance has long been an impediment to the success of new information systems. The present research addresses why users accept or reject information systems and how user acceptance is affected by system design features. The technology acceptance model (TAM) specifies the causal relationships between system design features, perceived usefulness, perceived ease of use, attitude toward using, and actual usage behavior. Attitude theory from psychology provides the rationale for hypothesized model relationships, and validated measures were used to operationalize model variables. A field study of 112 users regarding two end-user systems was conducted to test the hypothesized model. TAM fully mediated the effects of system characteristics on usage behavior, accounting for 36% of the variance in usage. Perhaps the most striking finding was that perceived usefulness was 50% more influential than ease of use in determining usage, underscoring the importance of incorporating the appropriate functional capabilities in new systems. Overall, TAM provides an informative representation of the mechanisms by which design choices influence user acceptance, and should therefore be helpful in applied contexts for forecasting and evaluating user acceptance of information technology. Implications for future research and practice are discussed.
Solution conformation of maltose from optical rotation: A procedure for evaluating carbohydrate force fields

As one means of evaluating the various force fields that are being developed for the molecular modeling of carbohydrate structures, the statistically averaged optical rotation of β-maltose can be calculated using the energy surface to be tested in combination with the detailed conformation dependence of β-maltose optical rotation presented here. Comparison with the observed rotation will indicate the quality of the force field, especially with respect to the parameterization of solvent effects. © 1992 John Wiley & Sons, Inc.
Biological considerations in assessing exposures to genotoxic and carcinogenic agents.

This analysis of the relationship between long-term exposure to carcinogens and the risk of cancer relies upon a model which depicts exposure, burden and genetic damage as time series. It is shown that the dose of the carcinogen and the resulting damage to susceptible tissues can be related to cumulative exposure provided that linear kinetics are maintained and the exposure series remains stationary. Since saturable processes can lead to nonlinear behavior, the role of metabolism is investigated. It is argued that by maintaining the mean burden below 1/8 of the value of KM the contribution of nonlinear kinetics to the dose should be minimal, at least in occupational settings where saturable metabolism is most likely. Under this conjecture an expression is derived for the maximum mean air concentration, designated Xmax, which should maintain linear kinetics. By comparing values of Xmax, estimated for five genotoxic and/or carcinogenic substances (benzene, styrene, tetrachloroethylene, trichloroethylene, and vinyl chloride) with the corresponding U.S. occupational exposure limits, it is shown that saturable metabolism is unlikely to occur in some situations but is likely in others. This suggests that biological monitoring can play an important role in defining dose-response relationships for some, but not all, carcinogenic substances.
K-ras activation generates an inflammatory response in lung tumors

Activating mutations in K-ras are one of the most common genetic alterations in human lung cancer. To dissect the role of K-ras activation in bronchial epithelial cells during lung tumorigenesis, we created a model of lung adenocarcinoma by generating a conditional mutant mouse with both Clara cell secretory protein (CC10)-Cre recombinase and the Lox-Stop-Lox K-rasG12D alleles. The activation of K-ras mutant allele in CC10 positive cells resulted in a progressive phenotype characterized by cellular atypia, adenoma and ultimately adenocarcinoma. Surprisingly, K-ras activation in the bronchiolar epithelium is associated with a robust inflammatory response characterized by an abundant infiltration of alveolar macrophages and neutrophils. These mice displayed early mortality in the setting of this pulmonary inflammatory response with a median survival of 8 weeks. Bronchoalveolar lavage fluid from these mutant mice contained the MIP-2, KC, MCP-1 and LIX chemokines that increased significantly with age. Cell lines derived from these tumors directly produced MIP-2, LIX and KC. This model demonstrates that K-ras activation in the lung induces the elaboration of inflammatory chemokines and provides an excellent means to further study the complex interactions between inflammatory cells, chemokines and tumor progression.
DRAINAGE OF THE THORACIC DUCT IN EXPERIMENTAL PERITONITIS

1. When care is taken to produce a peritonitis, which in itself is almost uniformly fatal, drainage of the thoracic duct in dogs has no favorable influence upon the course or result of the peritonitis. 2. Under the conditions of my experiments the thoracic duct did not serve in any important way as a drainage tract for bacterial contamination of the peritoneal cavity.