cssi/SciSciGPT-SciSciNet huggingface dataset:
Genetic Factors in Aging

Publisher Summary This chapter reviews that aging has two rather distinct components: The “nuisance” factor and the mortality factor, resulting from the development of degenerative diseases. Diseases, such as arthritis, obviously have components of each. Both result at least in part from mutations in somatic cells. The “nuisance” symptoms of aging can be explained as due to cell loss in postmitotic somatic cells, which is probably caused by lethal mutations in single genes. The degenerative diseases are initiated by very rare cellular events, each disease probably requiring about six such events for initiation, only one or two of which are mutations. The nature of the other steps is largely unknown. Probably some of the steps take place in cells and not in the target organ. Cells in the immune recognition system must also be altered to allow the development of aberrant cells in the target organ. The chapter highlights that all somatic cells undergo spontaneous mutation, and once a cell has suffered a mutation, which may eventually lead to a degenerative disease, it is not eliminated from the cell pool by cell selection. It may take a very long time before the mutation manifests because a number of other quite improbable events must also take place.
Quadrupolar NMR of Superconductors

NMR has played a central role in the study of superconductivity, providing detailed microscopic information about the superconducting order. In many of the recently discovered unconventional superconductors, the quadrupolar nature of the nuclei under investigation has yielded new information that would have been unavailable for spin I = 1/2 nuclei. In this article, we review some of the key discoveries enabled by quadrupolar NMR and discuss the basic science of the superconductivity in these materials. Keywords: NQR; superconductivity; magnetism; high-Tc; iron pnictides; heavy fermions
Three-dimensional flow simulations for supersonic mixed-compression inlets at incidence

An analysis is presented for calculating the steady three-dimensional flow field in supersonic mixedcompression inlets at incidence. A zonal modeling approach is employed to obtain the solution. The supersonic core flow is computed using a second-order pentahedral bicharacteristic algorithm. The bow shock wave and the reflected internal shock train are determined using a three-dimensio nal discrete shock-fitting procedure. The boundary-layer flow adjacent to both the centerbody and the cowl is computed using a second-order implicit finite difference method. The flow in a shock-wave/boundary-layer interaction region is computed using an integral formulation. The culmination of this research effort is the development of a production-type computer program capable of analyzing the flow in a variety of mixed-compres sion aircraft inlets. Numerical results and correlations with experiment are presented to illustrate application of the analysis.
Paracrine mechanisms of mouse mammary ductal growth.

Ductal growth during puberty is stimulated by estrogens, which elicit their effects via specific estrogen receptors, ERα and ERβ. Analysis of mice with targeted disruption of ERa or ERb has emphasized the importance of ERa in mammary gland development. In the mouse mammary gland, ERα are expressed in both epithelial and stromal cells (Kurita and Cunha, unpublished), which raises the possibility that the growth and morphogenetic effects of estrogen could be mediated via either epithelial or stromal ER. The aim of this paper is to review the role of epithelial versus stromal ER in mammary ductal-alveolar growth to assess the importance of paracrine mechanisms.
Performance of Organizational Design Models and Their Impact on Organization Learning

The performance of various organizational structures is an essential parameter in the reengineering of organizations, particularly in the current rapidly changing, competitive and information technology-dependent environment. This situation has generally resulted in a smaller workforce confronted with voluminous information-processing requirements. Naturally, the focus has been on the design of organzations that will support effective and efficient learning processes. This specific study is on the contingency modely by Ouksel et al. (1997) on the impact of organizational structure on organizational learning and performance. It expands the empirical evaluation of the model to test its robustness. This is done by conducting extensive simulations with (a) a larger number of variables in the decision tasks, and (b) a larger set of numbers for each of the numeric variables, than has been used in the past. Overall, the validity of previous results achieved has been confirmed, but the selection of the most appropriate design, that which will indeed improve learning, is even more nuanced than past studies have concluded.
Updating the Argument for Permitting and Federally Funding Stem Cell Research

Stem cell technology has advanced in recent years, raising the question of whether we might be able to bypass those concerns which traditionally have troubled opponents of stem cell research the most. In this light, we examine the major new techniques for the creation of human stem cell lines (HSCs), including induced pluripotent stem cells (iPS) and somatic cell nuclear transfer (SCNT) in order to assess whether either of these two alternatives are practically or ethically more advantageous than a reliance on the use of embryos procured in excess from in vitro fertilization (IVF). We conclude that these more recent techniques provide neither functionally comparable alternatives nor a straightforward escape from the moral difficulties involved in embryonic destruction. We then address anew the question of permissibility of stem cell research in comparison with two other biomedical ethical issues, namely, abortion and euthanasia. Finally, availing ourselves of the doctrine of double effect, we advocate for a permissive policy regarding the use of embryos in stem cell research and additionally provide fresh grounds for allocating federal funds for this research within a pluralistic society.
Politics After Television: Hindu nationalism and the cultural forms of Indian politics

The Ramayan epic was serialized on national television in India from January 1987 to August 1989. During the broadcast, the Ram Janmabhumi (Birthplace of Ram) movement, which aimed to demolish a mosque, Babri Masjid (Babur's mosque) in Ayodhya and build a Ram temple in its place, grew in importance. The Ramayan serial overlapped with the most crucial phase of the Janmabhumi movement, when it changed from an ominous but still relatively obscure campaign into the dominant issue before the country, one that made and unmade prime ministers and ruling parties. The Ramayan achieved record viewership in virtually every part of the country (something no serial before it had done), and made Sunday mornings “belong” to it; any public event scheduled for that time courted disaster. With such publicity given to its pre-eminent symbol, the god-king Ram, the Hindu nationalist Bharatiya Janata Party was emboldened to declare, by the middle of 1989, that the Ayodhya movement “had reached a state and status in Indian public life when it was no more possible to ignore its effect in politics, including electoral politics.” The issue was officially declared to be political, with the BJP making it their number one priority that “a grand temple to Lord Ram” would be built at the site of the mosque.
Albinism: Update on Ocular Features

Oculocutaneous albinism (OCA) and ocular albinism (OA) are disorders of abnormal melanogenesis. The ocular features of these hypopigmentation disorders and how they affect the visual function and ocular structure are becoming more defined. A hallmark of OCA and OA is the variability in phenotypic expression. Recent advances in genetic analysis and theories on the interaction of genes that alter expression in albinism have helped our understanding of this variable expression. Molecular genetics has also advanced the understanding of the interactions at the biochemical and cellular level that alter normal function and development. Additionally, major strides have been made in defining the anatomic structural deficits in the macula, retina, optic nerve, and optic pathway. Although our understanding of albinism has greatly advanced, the treatment of the functional visual deficit remains primarily supportive in nature. The promise for effective treatment paradigms is on the horizon.
Accuracy of multiecho magnitude‐based MRI (M‐MRI) for estimation of hepatic proton density fat fraction (PDFF) in children

Author(s): Zand, Kevin A; Shah, Amol; Heba, Elhamy; Wolfson, Tanya; Hamilton, Gavin; Lam, Jessica; Chen, Joshua; Hooker, Jonathan C; Gamst, Anthony C; Middleton, Michael S; Schwimmer, Jeffrey B; Sirlin, Claude B | Abstract: PurposeTo assess accuracy of magnitude-based magnetic resonance imaging (M-MRI) in children to estimate hepatic proton density fat fraction (PDFF) using two to six echoes, with magnetic resonance spectroscopy (MRS) -measured PDFF as a reference standard.MethodsThis was an IRB-approved, HIPAA-compliant, single-center, cross-sectional, retrospective analysis of data collected prospectively between 2008 and 2013 in children with known or suspected nonalcoholic fatty liver disease (NAFLD). Two hundred eighty-six children (8-20 [mean 14.2 ± 2.5] years; 182 boys) underwent same-day MRS and M-MRI. Unenhanced two-dimensional axial spoiled gradient-recalled-echo images at six echo times were obtained at 3T after a single low-flip-angle (10°) excitation with ≥ 120-ms recovery time. Hepatic PDFF was estimated using the first two, three, four, five, and all six echoes. For each number of echoes, accuracy of M-MRI to estimate PDFF was assessed by linear regression with MRS-PDFF as reference standard. Accuracy metrics were regression intercept, slope, average bias, and R(2) .ResultsMRS-PDFF ranged from 0.2-40.4% (mean 13.1 ± 9.8%). Using three to six echoes, regression intercept, slope, and average bias were 0.46-0.96%, 0.99-1.01, and 0.57-0.89%, respectively. Using two echoes, these values were 2.98%, 0.97, and 2.72%, respectively. R(2) ranged 0.98-0.99 for all methods.ConclusionUsing three to six echoes, M-MRI has high accuracy for hepatic PDFF estimation in children.
Chapter IX Methods for Studying the Microbial Division Cycle

Publisher Summary This chapter provides the methods for studying the microbial division cycle. Studies on the course of biochemical events during the microbial division cycle generally require techniques for identifying or isolating large numbers of cells of the same age. The choice of technique for an investigation on the cell cycle is dictated by the organism and type of experiment. In general, however, classification techniques are preferable to synchronization techniques. The fundamental difference between these two approaches to cell-cycle studies is that with synchronization techniques the age of the cells to be analyzed is known, but their physiological state is somewhat uncertain. In the classification techniques, the age is somewhat uncertain, but the physiological state of the cells is predetermined. In the latter case the precise age of the cells to be analyzed may be uncertain, but it can usually be determined within certain experimental limits. On the other hand, the extent to which a synchronization treatment causes a change in state is difficult to estimate without reference to an untreated control. In either case, the centrifugation and membrane-elution techniques are recommended for most experiments, since they combine minimum distortion with reasonably good resolution. The chapter classifies the techniques—by size, age, and specialized techniques.
Generating artificial neural networks for value function approximation in a domain requiring a shifting strategy

Artificial neural networks have been successfully used as approximating value functions for tasks involving decision making. In domains where a shift in judgment for decisions is necessary as the overall state changes, it is hypothesized that multiple neural networks are likely be beneficial as an approximation of a value function over those that employ a single network. For our experiments, the card game Dominion was chosen as the domain. This work compares neural networks generated by various machine learning methods successfully applied to other games (such as in TD-Gammon) to a genetic algorithm method for generating two neural networks for different phases of the game along with evolving a transition point. The results demonstrate a greater success ratio with the method hypothesized. This suggests future work examining more complex multiple neural network configurations could apply to this game domain as well as being applicable to other problems.
Governance and CEO Turnover: Do Something or Do the Right Thing?

Shareholder delegation of the power to fire the CEO to the board of directors is central to corporate governance. While the board ideally acts as desired by shareholders, board entrenchment may insulate a poorly performing manager from shareholders agitating for her removal. The conventional 'costly firing' model of managerial entrenchment views this protection from shareholders as purely negative. Yet recent anecdotal evidence on managerial turnover suggests an alternative view of entrenchment: If shareholders misattribute poor performance to the CEO rather than to circumstance, then insulating management from the whims of shareholders may lead to better firing decisions. We propose that entrenchment has an inherent trade-off. We present a model that directly incorporates both sides of this trade-off, and generates a set of empirical predictions that we explore using recently collected data on governance statutes and on the dismissals of CEOs of large U.S. corporations. Our results demonstrate that governance is a very important mediating factor in the relationship between performance and firing. Furthermore, we find support for the 'misguided shareholder' view of entrenchment. Fundamentally this paper explores whether, in caving in to shareholder demands, boards act in the best interests of shareholders or simply respond to their whims: Do they do just do something, or do they do the right thing?
Simultaneous liver and colorectal resections are safe for synchronous colorectal liver metastasis.

Abstract Background The optimal surgical strategy for the treatment of synchronous resectable colorectal liver metastasis has not been defined. The aims of this study were to review our experience with synchronous colorectal metastasis and to define the safety of simultaneous versus staged resection of the colon and liver. Study design From September 1984 through November 2001, 240 patients were treated surgically for primary adenocarcinoma of the large bowel and synchronous hepatic metastasis. Clinicopathologic, operative, and perioperative data were reviewed to evaluate selection criteria, operative methods, and perioperative outcomes. Results One hundred thirty-four patients underwent simultaneous resection of a colorectal primary and hepatic metastasis in a single operation (Group I), and 106 patients underwent staged operations (Group II). Simultaneous resections tend to be performed for right colon primaries (p Conclusions Simultaneous colon and liver resection is safe and efficient in the treatment of patients with colorectal cancer and synchronous liver metastasis. By avoiding a second laparotomy, the overall complication rate is reduced, with no change in operative mortality. Given its reduced morbidity, shorter treatment time, and similar cancer outcomes, simultaneous resection should be considered a safe option in patients with resectable synchronous colorectal metastasis.
Trading monitoring cockpit: conceptual architecture

We are witnessing the rise of robots in the finance industry in which human capabilities are largely surpassed by the capabilities of trading robots, and where solutions to several conundrums should be explored and sought. We describe this domain, explore some fundamental questions and suggest the Trading Monitoring Cockpit as a possible aide to human traders. This is work in progress, and we base our claims on assumptions and theoretical concepts and not on any practical experiments, nor real-world data collections.
Recruitment of mast cells to muscle after mild damage

We followed the response of muscle following mild intentional injury to determine a temporal sequence of cellular events involved in muscle repair. We found that intramuscular saline injection induced mild damage to muscle which resulted in the gradual recruitment of mast cells. Around the needle track, mast cells appear around 8 h post-injection. Mast cell accumulation were most dramatic immediately neighboring the posterior tibial vessels supplying the injured muscle. Dystrophin-deficient mdx muscle showed mast cell accumulations 3-fold higher than normal muscle, and this number did not change after saline injection. Additionally, we show that stem cell factor (SCF), a known mast cell chemoattractant, is expressed in both normal and mdx muscle at high levels. This steady-state level did not appear to be influenced by injury or dystrophin status. The implications of these findings are discussed as they relate to the repair of injured muscle and to their possible significance in the pathophysiology of Duchenne muscular dystrophy.
A Study of Contactor Servomechanisms with Positive Hysteresis

A contactor servomechanism is analyzed and constructed. The system is compensated by using positive hysteresis characteristics. It is shown that stability and dynamic, or transient, response are greatly improved by compensation in this manner. From an analytical study, it is shown that this type of compensation can achieve stability in cases where normal phase-lead compensation might fail. As a practical application of positive hysteresis compensation, a laboratory model is constructed and tested. The experimental results verify the analytical study.
Fine particle formation and transport in the Colstrip, Montana, powerplant plume

Abstract Smoke plumes of greater width but lesser thickness than predicted by Gaussian diffusion models have been documented by measurements from aircraft of the Colstrip, Montana, powerplant plume at downwind distances of 4–25 km. The plume has also been shown to be deflected as much as 20° away from the prevailing wind direction by the terrain. A particle formation rate of ~ 1016 s−1 in the plume over down-wind distances of 25–30 km has been estimated by using the plume profile measurements.
Katechon: Carl Schmitt's Imperial Theology and the Ruins of the Future

ABSTRACT The author proposes an imperial genealogy of Schmitt's concept of the katechon. Engaging debates about the role of the concept in Schmitt's political theology, the author reads the katechon as a scenario of imperial ruin gazing, tracing its emergence in essays about World War II, which focused on the theme of imperial rise and decline. With the katechon, Schmitt re-conceptualized Reich/empire/nomos as the inextricable link between beginning and end.
A trajectory for homeland ballistic missile defense

The Ground-based Midcourse Defense system is intended to protect the US homeland against limited attacks from intermediate- and long-range ballistic missiles. It has succeeded in intercepting target missiles and can engage a threat launched from North Korea or the Middle East, targeting any point in the USA. Nevertheless, high-profile struggles and program changes related to homeland ballistic missile defense (BMD) continue to make headlines. The most significant struggle has been a string of three straight intercept test failures over five years, followed by the recent successful intercept test in June 2014. This article first briefly reviews the current threats of concern. It then examines homeland BMD policy objectives, followed by the current major technical issues in supporting these objectives and, then, the likelihood of negating a warhead. Finally, it highlights major considerations that should be part of the trajectory the US government takes moving forward.
Association algebras for finite projective planes

The plane 71 is a finite plane when the set of points is finite and it is an elementary consequence of the above axioms that finite planes have n* + n + 1 lines and the same number of points. Such a plane is said to be of order n [4]. In this paper, we study projective planes of order n and show how to associate a commutative algebra of matrices with each plane. This algebra is the Bose-Mesner algebra which exists whenever there exists an association scheme on some set X. In Section 2 we are able to give necessary and suflicient conditions for the existence of a plane of order n.
Is peroxisome proliferation an obligatory precursor step in the carcinogenicity of di(2-ethylhexyl)phthalate (DEHP)?

Di(2-ethylhexyl)phthalate (DEHP), a peroxisome proliferator, has been listed by the International Agency for Research on Cancer (IARC) and by the National Toxicology Program as a possible or reason...
Results of irradiation in the squamous cell carcinomas of the anterior faucial pillar-retromolar trigone

Abstract Between January 1966 and August 1981, 159 patients with previously untreated squamous cell carcinomas of the anterior faucial pillar or retromolar trigone received definitive radiation therapy at The University of Texas M.D.Anderson Hospital and Tumor Institute. All except 11 patients were treated by external radiation including combination of electron beams with high-energy photons or 60 to doses raging from 60 Gy to 75 Gy. In the NO patients, as a rule, only the ipsilateral subdigastric nodes were treated electively to a dose of 50 Gy. The 5-year determinate survival rate for the overall group was 83%. The cumulative recurrence rate showed that 92% of the patients had recurrence by 2 years. Therefore, all patients except those who died with no evidence of local disease less than 2 years after treatment were evaluated for local control. The failure rate for the evaluable patients was 29% for T 1 lesions, 30% for T 2 lesions, 24% for T 3 lesions, and 40% for T 4 lesions. After salvage surgery, which consisted of intraoral resection in one-third of the patients and of a composite operation in the other two-thirds, the ultimate failure rate was 0% for T 1 lesions, 6% for T 2 lesions, 8% for T 3 lesions, and 20% for T 4 lesions. Whereas stage was a poor indicator for treatment outcome, there was a significantly higher failure rate for infiltrative and/or ulcerated lesions (35%) than for exophytic or superficial lesions (15%). Histologic grade was of no prognostic significance, nor was there any significant difference in the failure rate for lesions originating on the anterior faucial pillar versus that for lesions on the retromolar trigone. Following radiotherapy, 30% of the patients developed some degree of bone exposure but only 5.6% (9 patients) required a segmental mandibular resection. The probability of bone exposure was not dose related and more likely reflected tumor location on the mucoperiosteum. Of the whole group, 16 patients (10%) experienced a neck failure with 8 ultimate failures after salvage surgery. Among the 16 patients who had neck failures, 13 were originally staged NO; 6 of these patients had failures that occurred in the electively treated ipsilateral subdigastric area, but the field was too small to cover the nodes adequately. Aspects of the radiotherapy techniques with combined electron and photon beams that may influence the treatment outcome are discussed.
Factors predictive of outcome after surgery for faecal incontinence

Background Surgical treatment of faecal incontinence may be categorized into procedures that either repair or augment the native sphincter mechanism or, alternatively, require construction of a neosphincter using either autologous tissue or an artificial device. Methods This article reviews the currently available surgical options for the treatment of faecal incontinence, discusses factors predictive of outcome, and includes an algorithm for treatment. Results and conclusion Procedures such as postanal repair, direct sphincter repair and reefing are seldom used. Overlapping repair has become the operation of choice in incontinent patients with isolated anterior defects in the external anal sphincter muscle, particularly in postobstetric trauma. Pudendal neuropathy seems to be a predictive factor of success, although this is not universally accepted. Total pelvic floor repair has been offered as a recent alternative. Neosphincter procedures include a gluteoplasty, non-stimulated and stimulated unilateral or bilateral graciloplasty and artificial bowel sphincter. The success and morbidity rates with the stimulated graciloplasty and artificial bowel sphincter appear similar. The newest alternative, sacral nerve stimulation, seems promising. In the final analysis, case selection and surgical judgement are probably the most important factors influencing the success of surgery for faecal incontinence. Presented as the Edinburgh Royal College of Surgeons invited lecture to the Association of Coloproctology of Great Britain and Ireland, Southport, UK, June 1999
Deglacial abrupt climate change in the Atlantic Warm Pool: A Gulf of Mexico perspective

[1] During the last deglaciation, Greenland ice core and North Atlantic sediment records exhibit multiple abrupt climate events including the Younger Dryas cold episode (12.9–11.7 ka). However, evidence for the presence of the Younger Dryas in the Gulf of Mexico (GOM) and the relationship between GOM sea surface temperature (SST) and high-latitude climate change is less clear. We present new Mg/Ca-SST records from two varieties of the planktonic foraminifer Globigerinoides ruber (white and pink) to assess northern GOM SST history from approximately 18.4–10.8 ka. Thirty-five accelerator mass spectrometry (AMS) 14C dates from Orca Basin core MD02-2550 provide excellent age control and document high sedimentation rates (∼40 cm/kyr). G. ruber (white and pink) Mg/Ca-SST data exhibit increases (∼4.6 ± 0.6°C and ∼2.2 ± 0.5°C, respectively) from at least 17.8–16.6 ka, with nearly decadal resolution that are early relative to the onset of the Bolling-Allerod interstadial. Moreover, G. ruber (white) SST decreases at 16.0–14.7 ka (∼1.0 ± 0.5°C) and 12.8–11.6 ka (∼2.4 ± 0.6°C) correlate to the Oldest and Younger Dryas in Greenland and Cariaco Basin. The G. ruber (pink) SST record, which reflects differences in seasonality and/or depth habitat, is often not in phase with G. ruber (white) and closely resembles Antarctic air temperature records. Overall, it appears that Orca Basin SST records follow Antarctic air temperature early in the deglacial sequence and exhibit enhanced seasonality during Greenland stadials.
Invariant Subspaces of the Ring of Functions on a Vector Space over a Finite Field

Abstract IfFqis the finite field of characteristicpand orderq = ps, let F (q) be the category whose objects are functors from finite dimensionalFq-vector spaces toFq-vector spaces, and with morphisms the natural transformations between such functors. A fundamental object in F (q) is the injectiveIFqdefined by I F q (V) = F q V* = S*(V)/(x q − x). We determine the lattice of subobjects ofIFq. It is the distributive lattice associated to a certain combinatorially defined poset I (p, s) whoseqconnected components are all infinite (with one trivial exception). An analysis of I (p, s) reveals that every proper subobject of an indecomposable summand ofIFqis finite. ThusIFqis Artinian. FilteringIFqand I (p, s) in various ways yields various finite posets, and we recover the main results of papers by Doty, Kovacs, and Krop on the structure ofS*(V)/(xq) overFq, andS*(V) over F p .
Reliability for systems of degrading components with distinct component shock sets

Abstract This paper studies reliability for multi-component systems subject to dependent competing risks of degradation wear and random shocks, with distinct shock sets. In practice, many systems are exposed to distinct and different types of shocks that can be categorized according to their sizes, function, affected components, etc. Previous research primarily focuses on simple systems with independent failure processes, systems with independent component time-to-failure, or components that share the same shock set or type of shocks. In our new model, we classify random shocks into different sets based on their sizes or function. Shocks with specific sizes or function can selectively affect one or more components in the system but not necessarily all components. Additionally the shocks from the different shock sets can arrive at different rates and have different relative magnitudes. Preventive maintenance (PM) optimization is conducted for the system with different component shock sets. Decision variables for two different maintenance scheduling problems, the PM replacement time interval, and the PM inspection time interval, are determined by minimizing a defined system cost rate. Sensitivity analysis is performed to provide insight into the behavior of the proposed maintenance policies. These models can be applied directly or customized for many complex systems that experience dependent competing failure processes with different component shock sets. A MEMS (Micro-electro mechanical systems) oscillator is a typical system subject to dependent and competing failure processes, and it is used as a numerical example to illustrate our new reliability and maintenance models.
Ecology, metabolism, and genetics of ruminal Selenomonads

AbstractSelenomonas ruminantium is one of the more prominent and functionally diverse bacteria present in the rumen and can survive under a wide range of nutritional fluctuations. Selenomonas is not a degrader of complex polysaccharides associated with dietary plant cell wall components, but is important in die utilization of soluble carbohydrates released from initial hydrolysis of these polymers by other ruminal bacteria. Selenomonads have multiple carbon flow routes for carbohydrate catabolism and ATP generation, and subspecies differ in dieir ability to use lactate. Some soluble carbohydrates (glucose, sucrose) appear to be transported via the phosphoenolpyruvate phosphotransferase system, while arabinose and xylose are transported by proton symport. High cell yields and the presence of electron transport components in Selenomonas strains has been documented repeatedly and this may partially account for the energy partitioning observed between energy consumed for growth and maintenance functions. Most...
The discontinuous glacio-eustatic fall in tertiary sea level

Abstract In eastern Antarctica at latitude 86° S and 3,000 m elevation, a solifluxion layer and overlying drifts from temperature glaciers are older than the East Antarctic Ice Sheet, which built up after the glacier tongues had reached low ground. The glacial-eustatic drop in sea level eventually amounted to about 60 m by the time this ice sheet had an equilibrium profile. Land ice also covered the western Antarctic archipelago, but no more could accumulate in Antarctica until further cooling allowed “cold” shelf ice to spread, thicken, and come to ground in the former strait between eastern Antarctica and the western Antarctic archipelago. The West Antarctic Ice Sheet then built up, causing an additional drop in sea level of about 5 m. Intensely glaciated landscapes in the Horlick Mountains, now partially buried by this ice sheet, indicate a long interval of glacial erosion in eastern Antarctica before the West Antarctic Ice Sheet existed. The Greenland Ice Sheet, with less critical temperature requirements, may have formed either during this interval, causing a further drop in sea level of about 6 m, or contemporaneously with the West Antarctic Ice Sheet, resulting in a total fall at that time of about 11 m. The crucial spread of Antarctic shelf ice preceded the formation of the first North American and European ice sheets, for until then temperatures were higher than they are today. It probably marks the Pliocene-Pleistocene transition, if this is defined as the point when falling temperatures first reached today's level.
Supracerebellar infratentorial approach to cavernous malformations of the brainstem: surgical variants and clinical experience with 45 patients.

OBJECTIVE: The supracerebellar infratentorial (SCIT) approach can be performed at the midline (median variant), lateral to the midline (paramedian variant), or at the level of the angle formed by the transverse and sigmoid sinuses (extreme lateral variant). We analyzed our experience with SCIT approaches for the surgical treatment of cavernous malformations of the brainstem (CMBs). METHODS: Demographic, clinical, radiologic, and surgical data from 45 patients (20 males and 25 females; mean age, 36.2 years) with CMBs surgically removed through SCIT approaches were reviewed retrospectively. Anatomic information was explored using cadaver head dissection. RESULTS: Twenty-three lesions were in the midbrain, 3 were at the midbrain and extended to the thalamus, 9 were at the pontomesencephalic junction, and 10 were in the upper pons. All patients presented with hemorrhage. The median variant was used in 13 patients, the paramedian variant in 9, and the extreme lateral variant in 23. Intraoperatively, all CMBs were associated with a developmental venous anomaly. At last follow-up, 88% of the patients were the same or better. After a mean follow-up of 20 months, their mean Glasgow Outcome Scale score was 4.1. CONCLUSION: SCIT approaches provide excellent exposure to CMBs located at the posterior incisural space, not only in the midline but also in the posterolateral surface of the upper pons and midbrain. Careful preoperative planning and neuronavigational assistance are needed to determine the best angle of attack and trajectory for SCIT approaches. Refined microsurgical techniques are paramount to achieve safe surgical removal of CMBs with good outcomes.
Dual models of pore spaces

We present a model for pore spaces that consists of two parts related by duality: (1) a decomposition of an open polyhedral pore space into open contractible pore bodies separated by relatively open interfaces and (2) a pore network that is homotopy equivalent to the pore space. The dual model is unique and free of parameters, but it relies on regularity conditions for the pore space. We show how to approximate any pore space by the interior of a polyhedral complex such that the regularity conditions are fulfilled. Thus, we are able to calculate the dual model from synthetic porous media and images of real porous media. The pore bodies are unions of relatively open Delaunay cells with respect to the corners of the pore boundary, and the pore network consists of certain at most two-dimensional (2D) Voronoi cells with respect to the corners of the pore boundary. The pore network describes the neighborhood relations between the pore bodies. In particular, any relatively open 2D Delaunay face f separating two pore bodies has a unique (relatively open) dual network edge. In our model, f is a pore throat only if it is hit by its dual network edge. Thus, as opposed to widespread intuition, any pore throat is convex, and adjacent pore bodies are not necessarily separated by pore throats. Due to the duality between the pore network and the decomposition of the pore space into pore bodies it is straightforward to store the geometrical properties of the pore bodies [pore throats] as attributes of the dual network vertices [edges]. Such an attributed network is used to perform 2D drainage simulations. The results agree very well with those from a pore-morphology based modeling approach performed directly on the digital image of a porous medium. Contractibility of the pore bodies and homotopy equivalence of the pore space and the pore network is proven using discrete Morse theory and the nerve theorem from combinatorial topology.
Dynamic Analysis of Rectilinear Motion of a Self-Propelling Disk With Unbalance Masses

This paper investigates the dynamics of a rolling disk with three unbalance masses that can slide along radial spokes equispaced in angular orientation. The objective is to design trajectories for the masses that satisfy physical constraints and enable the disk to accelerate or move with constant velocity. The disk is designed to remain vertically upright and is constrained to move along a straight line. We design trajectories for constant acceleration, first using a static model, and then through detailed analysis using a dynamic model. The analysis based on the dynamic model considers two separate cases; one where the potential energy of the system is conserved, and the other where it continually varies. Whereas trajectories conserving potential energy are quite similar to those obtained from the static model, the variable potential energy trajectories are the most general. A number of observations related to the system center-of-mass are made with respect to both trajectories. Following the strategy for constant acceleration maneuvers, we give a simple approach to tracking an acceleration profile and provide some simulation results. @DOI: 10.1115/1.1344903#
A new method for multicomponent activity coefficients of electrolytes in aqueous atmospheric aerosols

[1] Three-dimensional models of atmospheric inorganic aerosols need accurate and computationally efficient parameterizations of activity coefficients of various electrolytes in multicomponent aqueous solutions. In this paper, we extend the Taylor's series expansion mixing rule used by C. Wagner in 1952 for estimating activity coefficients in dilute alloy solutions to aqueous electrolyte solutions at any concentration. The resulting method, called the multicomponent Taylor expansion method (MTEM), estimates the mean activity coefficient of an electrolyte in a multicomponent solution on the basis of its values in binary solutions of all the electrolytes present in the mixture at the solution water activity aw, assuming aw is equal to the ambient relative humidity. MTEM is applied here for atmospheric aerosol systems containing H+, NH4+, Na+, Ca2+, SO42−, HSO4−, NO3−, and Cl− ions. The aerosol water content is calculated using the Zdanovskii-Stokes-Robinson (ZSR) method. For self-consistency, most of the MTEM and ZSR parameters are derived using the comprehensive Pitzer-Simonson-Clegg model at 298.15 K and are valid for an aw range of 0.2–0.97. Because CaSO4 is sparingly soluble, it is treated as a solid in the model over the entire aw range. MTEM is evaluated for several multicomponent systems representing various continental and marine aerosols and is contrasted against the mixing rule of C. L. Kusik and H. P. Meissner and of L. A. Bromley and the newer approach of S. Metzger and colleagues. Predictions of MTEM are found to be generally within a factor of 0.8–1.25 of the comprehensive Pitzer-Simonson-Clegg model and are shown to be significantly more accurate than predictions of the other three methods. MTEM also yields a noniterative solution of the bisulfate ion dissociation in sulfate-rich systems: a major computational advantage over other ionic-strength-based methods that require an iterative solution. CPU time requirements of MTEM relative to other methods for sulfate-poor and sulfate-rich systems are also discussed.
Neural‐glial interaction in the spinal cord for the development and maintenance of nerve injury‐induced neuropathic pain

Damage to the nervous system often results in neuropathic pain. Current treatment for this disabling state is unsuccessful due to our incomplete understanding of cellular mechanisms causing this pain. Although glial cells were largely ignored in most textbooks of pain, accumulating evidence over the last decade indicates an important role of glial cells in the pathogenesis of pain. Both microglia and astroglia are activated in the spinal cord after peripheral nerve injury. Importantly, activated microglia and astroglia produce multiple inflammatory mediators and neuromodulators, acting on primary afferents or dorsal horn neurons and leading to an enhancement and maintenance of dorsal horn neuron sensitization and subsequent pain sensitization. This neural-glial interaction after peripheral nerve injury is likely to be triggered by signaling molecules released in the spinal cord from central terminals of damaged sensory neurons, stimulating surrounding glial cells. In addition, there is a microglial-astroglial interaction; microglia activation occurs before astroglial activation and is known to cause astroglial activation. Glial activation is further enhanced by microglial-microglial interaction and astroglial-astroglial interaction. Many signaling molecules (e.g., MAP kinases, ATP receptors, chemokine receptors) are exclusively activated in spinal microglia or astroglia after nerve injury, and an inhibition of these molecules can attenuate neuropathic pain. Since traditional pain-killers are designed against neuronal targets and are only partially effective to treat neuropathic pain, searching for signaling molecules that are induced in spinal glia in neuropathic pain conditions will identify novel targets for the management of this debilitating chronic pain. Drug Dev. Res. 67:331–338, 2006. © 2006 Wiley-Liss, Inc.
Extracting more than a few eigenvectors from a dense real symmetric matrix: Optimal algorithms versus the architectural constraints of the FPS-X64

Ten widely available sets of routines, including HQRII, QCPE GIVENS and EISPACK 3, were evaluated for reliability, robustness, accuracy, speed, compactness, portability and simplicity. All were found lacking in one or more areas. Modified versions of the EISPACK routines TRED3, TQLRAT, TINVIT and TRBAK3 performed somewhat better. Changes to TINVIT were especially important for improved speed, accuracy and reliability. To achieve the maximum capabilities of the FPS-X64 series of computers access to table memory is required, but since the FORTRAN compiler does not allow this and there is no library support for the required operations, it was necessary to write three routines in APAL. The standard algorithm needs to be modified before full efficiency can be achieved for the back transformation.
Use of respiratory syncytial virus surveillance data to optimize the timing of immunoprophylaxis.

OBJECTIVE: For children in the United States who are at high risk for severe respiratory syncytial virus (RSV) infection, the American Academy of Pediatrics (AAP) recommends administering immunoprophylaxis during the RSV season. We present an approach to using surveillance data to help guide application of AAP recommendations for immunoprophylaxis to local patterns of RSV outbreaks. METHODS: We analyzed data from laboratories that report consistently to the National Respiratory and Enteric Virus Surveillance System from 1992 to 2007. Local RSV seasons were defined and an immunoprophylaxis schedule was determined by using the median onset dates from each laboratory during 2002–2007. We applied these dates to 10 preceding years of RSV detection data. We compared how well the 5-year median-based method and a fixed date method were able to match the timing of immunoprophylaxis to the RSV season. RESULTS: Nineteen laboratories met our inclusion criteria and generally experienced only 1 RSV outbreak per season. Five years of data gave similar median onset/offset dates and season duration, as did 10 years and 15 years of data. The 5-year median schedule increased the number of seasons that children were protected at the season onset by 15% compared with a fixed start date of November 1 and identified communities that experienced RSV seasons with extended durations. CONCLUSIONS: The 5-year median method can be used to characterize timing of RSV seasons and optimally apply the current AAP recommendations for timing of palivizumab prophylaxis to the local community.
An autocorrelation-based method for improvement of sub-pixel displacement estimation in ultrasound strain imaging

In ultrasound strain and elasticity imaging, an accurate and cost-effective sub-pixel displacement estimator is required because strain/elasticity imaging quality relies on the displacement SNR, which can often be higher if more computational resources are provided. In this paper, we introduce an autocorrelation-based method to cost-effectively improve subpixel displacement estimation quality. To quantitatively evaluate the performance of the autocorrelation method, simulated and tissue-mimicking phantom experiments were performed. The computational cost of the autocorrelation method is also discussed. The results of our study suggest the autocorrelation method can be used for a real-time elasticity imaging system.
Market exit and barriers to exit: Theory and practice

This article examines market exit, barriers to exit, modes and strategies of exit, reasons for exit, and the consequences of exit through a literature review of the academic literature and the popular press. There is very little empirical research in this area. The article attempts to analyze the applications of market exit and barriers to exit theories, and consequences of exit with recent examples taken from newspapers and popular business magazines. Despite the fact that there are strong barriers to exit, companies are sometimes forced to exit markets. Market-exit or product-elimination decisions influence employees, distributors, suppliers, and customers. This influence is usually negative and is in the form of cognitive dissonance. © 2000 John Wiley & Sons, Inc.
A perturbation theory for Love waves in anelastic media

Summary. We give a systematic formulation and a rigorous justification of a perturbation technique for the computation of the eigenvalues and eigenfunctions of Love waves (and toroidal oscillations by an appropriate change for variables) in an anelastic medium with a constitutive law modelling geophysical media of current interest such as the Kelvin—Voigt Solid, the Maxwell Solid, the Standard Linear Solid, and the Standard Linear Solid with a continuous spectrum of relaxation times. We develop expressions relating the eigenvalues of eigenfunctions for Love waves in a continuously varying vertically stratified anelastic half-space to the corresponding elastic eigenvalues and eigenfunctions. Analytically, our correspondence principle has the form of a regular perturbation expansion in terms of a parameter for both the eigenvalues and eigenfunctions. The identification of ɛ is motivated by the dissipativity principle of viscoelasticity theory. Moreover, we show that our correspondence principle applies respectively only in the high and low frequency range for the Maxwell and Kelvin—Voigt Solids. Outside of the applicable range of frequencies, our correspondence principle yields no useful information. For the family of Standard Linear Solids it is uniformly applicable for all non-zero frequencies. We also derive an explicit formula to estimate the radius of convergence of our perturbation expansions. This estimate of the radius of convergence for each eigenvalue and eigenfunction is functionally defined by the constitutive model for the anelastic medium. The estimate is frequency dependent and depends on the separation distance between the eigenvalue and the remainder of the spectrum of the corresponding elastic problem.
Time-integrating correlator based on fiber-optic delay lines.

A time-integrating correlator based on techniques of fiber-optic delay-line signal processing is described. We show that the time-integrating architecture does not suffer from limitations associated with previously demonstrated space-integrating fiber-optic correlators. Experimental results from an eight-channel time-integrating correlator are presented, demonstrating real-time autocorrelation of a 5-MHz square wave. Limitations of the experimental correlator are discussed, and an alternative design is proposed, with a potential time–bandwidth product of the order of 108.