Rapid Metabolic Recovery Following Vigorous Exercise in Burrow-Dwelling Larval Sea Lampreys (\u3cem\u3ePetromyzon marinus\u3c/em\u3e)

Although the majority of the sea lamprey’s (Petromyzon marinus) life cycle is spent as a burrow-dwelling larva, or ammocoete, surprisingly little is known about intermediary metabolism in this stage of the lamprey’s life history. In this study, larval sea lampreys (ammocoetes) were vigorously exercised for 5 min, and their patterns of metabolic fuel depletion and replenishment and oxygen consumption, along with measurements of net whole-body acid and ion movements, were followed during a 4–24-h postexercise recovery period. Exercise led to initial five- to sixfold increases in postexercise oxygen consumption, which remained significantly elevated by 1.5–2.0 times for the next 3 h. Exercise also led to initial 55% drops in whole-body phosphocreatine, which was restored by 0.5 h, but no significant changes in whole-body adenosine triphosphate were observed. Whole-body glycogen concentrations dropped by 70% immediately following exercise and were accompanied by a simultaneous ninefold increase in lactate. Glycogen and lactate were quickly restored to resting levels after 0.5 and 2.0 h, respectively. The presence of an associated metabolic acidosis was supported by very high rates of metabolic acid excretion, which approached 1,000 nmol g-1 during the first 2 h of postexercise recovery. Exercise-induced ion imbalances were also rapidly alleviated, as initially high rates of net Na+ and Cl- loss (—1,200 nmol g-1h-1 and —1,800 nmol g-1h-1 respectively) were corrected within 1–2 h. Although larval sea lampreys spend most of their time burrowed, they are adept at performing and recovering from vigorous anaerobic exercise. Such attributes could be important when these animals are vigorously swimming or burrowing as they evade predators or forage

SUSTAINING A COMMUNITY OF SCHOLARS AT A TRANSNATIONAL UNIVERSITY: A SELF-STUDY

In this article we report on a self-study at a transnational researchintensive university in Qatar. We trace the shared perceptions of four emerging scholars, from two disciplines, coming together to build a sustainable community of scholars as an interdisciplinary team. We explore our initial thoughts in developing our group and illustrate the themes of collegiality, mentorship and conflict in sustaining a successful community of scholars. We conclude with lessons learned illustrating how the concept of support played a significant factor in sustaining our community and adjusting to both a transnational education setting and expatriate life. The findings may serve useful to others working in such a setting, and most expressively, provide an opportunity to broaden the continued scholarly discourses of scholarship, community of scholars, and interdisciplinary teams within the context of transnational education

SUSTAINING A COMMUNITY OF SCHOLARS AT A TRANSNATIONAL UNIVERSITY: A SELF-STUDY

In this article we report on a self-study at a transnational researchintensive university in Qatar. We trace the shared perceptions of four emerging scholars, from two disciplines, coming together to build a sustainable community of scholars as an interdisciplinary team. We explore our initial thoughts in developing our group and illustrate the themes of collegiality, mentorship and conflict in sustaining a successful community of scholars. We conclude with lessons learned illustrating how the concept of support played a significant factor in sustaining our community and adjusting to both a transnational education setting and expatriate life. The findings may serve useful to others working in such a setting, and most expressively, provide an opportunity to broaden the continued scholarly discourses of scholarship, community of scholars, and interdisciplinary teams within the context of transnational education

Polytope Representations for Linear-Programming Decoding of Non-Binary Linear Codes

In previous work, we demonstrated how decoding of a non-binary linear code could be formulated as a linear-programming problem. In this paper, we study different polytopes for use with linear-programming decoding, and show that for many classes of codes these polytopes yield a complexity advantage for decoding. These representations lead to polynomial-time decoders for a wide variety of classical non-binary linear codes.Comment: 5 pages, to appear in 2008 IEEE International Symposium on Information Theor

Irritable bowel syndrome

This issue of eMedRef provides information to clinicians on the pathophysiology, diagnosis, and therapeutics of irritable bowel syndrome

Computation of the entropy of polynomials orthogonal on an interval.

We give an effective method to compute the entropy for polynomials orthogonal on a segment of the real axis that uses as input data only the coefficients of the recurrence relation satisfied by these polynomials. This algorithm is based on a series expression for the mutual energy of two probability measures naturally connected with the polynomials. The particular case of Gegenbauer polynomials is analyzed in detail. These results are applied also to the computation of the entropy of spherical harmonics, important for the study of the entropic uncertainty relations as well as the spatial complexity of physical systems in central potentials

Towards a Definitive Measure of Repetitiveness

Unlike in statistical compression, where Shannon’s entropy is a definitive lower bound, no such clear measure exists for the compressibility of repetitive sequences. Since statistical entropy does not capture repetitiveness, ad-hoc measures like the size z of the Lempel–Ziv parse are frequently used to estimate repetitiveness. Recently, a more principled measure, the size γ of the smallest string attractor, was introduced. The measure γ lower bounds all the previous relevant ones (including z), yet length-n strings can be represented and efficiently indexed within space O(γlognγ), which also upper bounds most measures (including z). While γ is certainly a better measure of repetitiveness than z, it is NP-complete to compute, and no o(γlog n) -space representation of strings is known. In this paper, we study a smaller measure, δ≤ γ, which can be computed in linear time. We show that δ better captures the compressibility of repetitive strings. For every length n and every value δ≥ 2, we construct a string such that γ=Ω(δlognδ). Still, we show a representation of any string S in O(δlognδ) space that supports direct access to any character S[i] in time O(lognδ) and finds the occ occurrences of any pattern P[1.m] in time O(mlog n+ occlogεn) for any constant ε> 0. Further, we prove that no o(δlog n) -space representation exists: for every length n and every value 2 ≤ δ≤ n1-ε, we exhibit a string family whose elements can only be encoded in Ω(δlognδ) space. We complete our characterization of δ by showing that, although γ, z, and other repetitiveness measures are always O(δlognδ), for strings of any length n, the smallest context-free grammar can be of size Ω(δlog2n/ log log n). No such separation is known for γ

Caribbean Corals in Crisis: Record Thermal Stress, Bleaching, and Mortality in 2005

BACKGROUND The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. METHODOLOGY/PRINCIPAL FINDINGS Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. CONCLUSIONS/SIGNIFICANCE Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate.This work was partially supported by salaries from the NOAA Coral Reef Conservation Program to the NOAA Coral Reef Conservation Program authors. NOAA provided funding to Caribbean ReefCheck investigators to undertake surveys of bleaching and mortality. Otherwise, no funding from outside authors' institutions was necessary for the undertaking of this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Motivación y estimación del tiempo en el uso de herramientas internet informacionales y dialógicas

Se analiza la relación existente entre el grado de interés o motivación y estimación del tiempo (aspectos psicológicos) en la realización de tareas informacionales y dialógicas (aspectos comunicacionales) mediadas por internet en adolescentes chilenos. Se empleó una muestra estratificada de 120 estudiantes de 7 liceos de Chile con una media de edad de 15 años. Todos los participantes debían realizar de forma sucesiva dos tareas por internet: una primera tarea de comunicación vertical (búsqueda de información con el empleo del Google) y una segunda tarea de comunicación horizontal (diálogo por mensajería). Para cada una de las tareas se medía el tiempo percibido y el grado de interés. Los resultados muestran un interés significativamente mayor y un tiempo estimado significativamente menor en la tarea de comunicación horizontal. Desde aquí se pueden proyectar usos informacionales y educativos de interne