bluuebunny/crossref_metadata_2025 huggingface dataset:
Statistical Process Control and Condition‐Based Maintenance: A Meaningful Relationship through Data Sharing
Authors: Panagiotidou Sofia , Tagaras George
Published: October 2009

This paper focuses on the close relationship between statistical process control and preventive maintenance (PM) of manufacturing equipment. The context is very general: a production process that is characterized by multiple distinct operational states and a failure state. The operational states differ in terms of operational/quality costs and/or the proneness to complete failure. The times of shift from the normal operational state to an inferior one and the times to failure are random variables, not necessarily exponentially distributed. The process is monitored with a control chart with the purpose of quickly detecting shifts to an inferior operational state due to the occurrence of some unobservable assignable cause. At the same time, the information collected from the process may be used to re‐schedule the planned PM, if there is evidence that a failure is imminent. The two mechanisms are obviously related, especially if they are based on measurements of the same critical process characteristic. Yet, they are typically treated independently. We develop a fairly general mathematical model for the joint optimization of the control chart parameters and the maintenance times. Numerical investigation using this model shows that ignoring the close relationship between process control and maintenance results in inefficiencies that may be substantial. It also provides practical insights about the effects of some key problem characteristics on the optimal joint design of process control and maintenance.
Single‐Period Two‐Product Assemble‐to‐Order Systems with a Common Component and Uncertain Demand Patterns
Authors: Xiao Yongbo , Chen Jian , Lee Chung‐Yee
Published: October 2009

We consider a single‐period assemble‐to‐order system that produces two types of end products to satisfy two independent and stochastic customer orders. Each type of product is used to fulfill a particular customer order and these two products share a common component. Furthermore, one customer may confirm her order before the other one, and the manufacturer needs to make a commitment immediately upon the receipt of each customer order on how many products to be delivered. We propose a model for optimizing the inventory and production decisions under the above ATO environment. We also extend our model to the situation where the manufacturer can fulfill the unsatisfied low‐priority demand using the left‐over inventories after fulfilling the high‐priority demand, in case the low‐priority customer arrives first. Numerical experiments are conducted, which provide some interesting insights on the impact of uncertain demand pattern.
Dynamic Assignment of Flexible Service Resources
Authors: Akçay Yalçιn , Balakrishnan Anant , Xu Susan H.
Published: October 2009

Resource flexibility is an important tool for firms to better match capacity with demand so as to increase revenues and improve service levels. However, in service contexts that require dynamically deciding whether to accept incoming jobs and what resource to assign to each accepted job, harnessing the benefits of flexibility requires using effective methods for making these operational decisions. Motivated by the resource deployment decisions facing a professional service firm in the workplace training industry, we address the dynamic job acceptance and resource assignment problem for systems with general resource flexibility structure, i.e., with multiple resource types that can each perform different overlapping subsets of job types. We first show that, for systems containing specialized resources for individual job types and a versatile resource type that can perform all job types, the exact policy uses a threshold rule. With more general flexibility structures, since the associated stochastic dynamic program is intractable, we develop and test three optimization‐based approximate policies. Our extensive computational tests show that one of the methods, which we call the Bottleneck Capacity Reservation policy, is remarkably effective in generating near‐optimal solutions over a wide range of problem scenarios. We also consider a model variant that requires dynamic job acceptance decisions but permits deferring resource assignment decisions until the end of the horizon. For this model, we discuss an adaptation of our approximate policy, establish the effectiveness of this policy, and assess the value of postponing assignment decisions.
When and why amino acids?
Authors: Krnjević Krešimir
Published: October 2009

This article reviews especially the early history of glutamate and GABA as neurotransmitters in vertebrates. The proposal that some amino acids could mediate synaptic transmission in the CNS initially met with much resistance. Both GABA and its parent glutamate are abundant in the brain; but, unlike glutamate, GABA had no obvious metabolic function. By the late 1950s, the switch of interest from electrical to chemical transmission invigorated the search for central transmitters. Its identification with Factor I, a brain extract that inhibited crustacean muscle, focused interest on GABA as a possible inhibitory transmitter. In the first microiontophoretic tests, though GABA strongly inhibited spinal neurons, these effects were considered ‘non‐specific’. Strong excitation by glutamate (and other acidic amino acids) led to the same conclusion. However, their great potency and rapid actions on cortical neurons convinced other authors that these endogenous amino acids are probably synaptic transmitters. This was partly confirmed by showing that both IPSPs and GABA greatly increased Cl−conductance, their effects having similar reversal potentials. Many anticonvulsants proving to be GABA antagonists, by the 1970s GABA became widely accepted as a mediator of IPSPs. Progress was much slower for glutamate. Being generated on distant dendrites, EPSPs could not be easily compared with glutamate‐induced excitation, and the search for specific antagonists was long hampered by the lack of blockers and the variety of glutamate receptors. These difficulties were gradually overcome by the application of powerful techniques, such as single channel recording, cloning receptors, as well as new pharmacological tools.
Chronic high fat feeding attenuates load‐induced hypertrophy in mice
Authors: Sitnick Mitchell , Bodine Sue C. , Rutledge John C.
Published: October 2009

The incidence of obesity and obesity‐related conditions, such as metabolic syndrome and insulin resistance, is on the increase. The effect of obesity on skeletal muscle function, especially the regulation of muscle mass, is poorly understood. In this study we investigated the effect of diet‐induced obesity on the ability of skeletal muscle to respond to an imposed growth stimulus, such as increased load. Male C57BL/6 mice were randomized into two diet groups: a low fat, high carbohydrate diet (LFD) and a high fat, low carbohydrate diet (HFD) fedad libitumfor 14 weeks. Mice from each diet group were divided into two treatment groups: sedentary control or bilateral functional overload (FO) of the plantaris muscle. Mice were evaluated at 3, 7, 14 or 30 days following FO. By 14 days of FO, there was a 10% reduction (P< 0.05) in absolute growth of the plantaris in response to overload in HFD micevs.LFD mice. By 30 days the attenuation in growth increased to 16% in HFD mice compared to LFD mice. Following FO, there was a reduction in the formation of polysomes in the HFD mice relative to the LFD mice, suggesting a decrease in protein translation. Further, activation of Akt and S6K1, in response to increased mechanical loading, was significantly attenuated in the HFD mice relative to the LFD mice. In conclusion, chronic high fat feeding impairs the ability of skeletal muscle to hypertrophy in response to increased mechanical load. This failure coincided with a failure to activate key members of the Akt/mTOR signalling pathway and increase protein translation.
Dehydration‐induced modulation of κ‐opioid inhibition of vasopressin neurone activity
Authors: Scott Victoria , Bishop Valerie R. , Leng Gareth , Brown Colin H.
Published: October 2009

Dehydration increases vasopressin (antidiuretic hormone) secretion from the posterior pituitary gland to reduce water loss in the urine. Vasopressin secretion is determined by action potential firing in vasopressin neurones, which can exhibit continuous, phasic (alternating periods of activity and silence), or irregular activity. Autocrine κ‐opioid inhibition contributes to the generation of activity patterning of vasopressin neurones under basal conditions and so we used in vivo extracellular single unit recording to test the hypothesis that changes in autocrine κ‐opioid inhibition drive changes in activity patterning of vasopressin neurones during dehydration. Dehydration increased the firing rate of rat vasopressin neurones displaying continuous activity (from 7.1 ± 0.5 to 9.0 ± 0.6 spikes s−1) and phasic activity (from 4.2 ± 0.7 to 7.8 ± 0.9 spikes s−1), but not those displaying irregular activity. The dehydration‐induced increase in phasic activity was via an increase in intraburst firing rate. The selective κ‐opioid receptor antagonist nor‐binaltorphimine increased the firing rate of phasic neurones in non‐dehydrated rats (from 3.4 ± 0.8 to 5.3 ± 0.6 spikes s−1) and dehydrated rats (from 6.4 ± 0.5 to 9.1 ± 1.2 spikes s−1), indicating that κ‐opioid feedback inhibition of phasic bursts is maintained during dehydration. In a separate series of experiments, prodynorphin mRNA expression was increased in vasopressin neurones of hyperosmotic rats, compared to hypo‐osmotic rats. Hence, it appears that dynorphin expression in vasopressin neurones undergoes dynamic changes in proportion to the required secretion of vasopressin so that, even under stimulated conditions, autocrine feedback inhibition of vasopressin neurones prevents over‐excitation.
Effects of short interval intracortical inhibition and intracortical facilitation on short interval intracortical facilitation in human primary motor cortex
Authors: Wagle‐Shukla Aparna , Ni Zhen , Gunraj Carolyn A. , Bahl Nina , Chen Robert
Published: October 2009

Short interval intracortical facilitation (SICF) can be elicited by transcranial magnetic stimulation (TMS) of the motor cortex (M1) with a suprathreshold first stimulus (S1) followed by a subthreshold second stimulus (S2). SICF occurs at three distinct phases and is likely to be related to the generation of indirect (I) waves. Short interval intracortical inhibition (SICI) is an inhibitory phenomenon and intracortical facilitation (ICF) is an excitatory phenomenon occurring in the M1 that can be studied with TMS. We studied the interactions between SICI/ICF and SICF in 17 healthy subjects. Six experiments were conducted. The first experiment examined the effects of different S1 intensities on SICI, ICF and SICF at three peaks. The effects of SICI on SICF were tested by a triple‐pulse TMS protocol in the second experiment. We performed Experiments 3–5 to further test the interactions between SICI and SICF with various strengths of SICI, at SICF peaks and troughs, and with SICF generated by different current direction which preferentially generates late I waves. The effects of ICF on SICF were examined in Experiment 6. The results showed that ICF and SICF decreased whereas SICI increased with higher S1 intensities. SICI facilitated SICF mediated by late I waves both at the peaks and the troughs of SICF. The increase of SICF in the presence of SICI correlated to the strength of SICI. ICF decreased the third peak of SICF. We conclude that SICI facilitates SICF at neuronal circuits responsible for generating late I waves through disinhibition, while ICF may have the opposite effects.
Differences in Transmural Pressure and Axial Loading Ex Vivo Affect Arterial Remodeling and Material Properties
Authors: Lawrence Amanda R. , Gooch Keith J.
Published: October 2009

Arterial axial strains, present in the in vivo environment, often become reduced due to either bypass grafting or the normal aging process. Since the prevalence of hypertension increases with aging, arteries are often exposed to both decreased axial stretch and increased transmural pressure. The combined effects of these mechanical stimuli on the mechanical properties of vessels have not previously been determined. Porcine carotid arteries were cultured for 9 days at normal and reduced axial stretch ratios in the presence of normotensive and hypertensive transmural pressures using ex vivo perfusion techniques. Measurements of the amount of axial stress were obtained through longitudinal tension tests while inflation-deflation test results were used to determine circumferential stresses and incremental moduli. Macroscopic changes in artery geometry and zero-stress state opening angles were measured. Arteries cultured ex vivo remodeled in response to the mechanical environment, resulting in changes in arterial dimensions of up to ∼25% and changes in zero-stress opening angles of up to ∼55°. While pressure primarily affected circumferential remodeling and axial stretch primarily affected axial remodeling, there were clear examples of interactions between these mechanical stimuli. Culture with hypertensive pressure, especially when coupled with reduced axial loading, resulted in a rightward shift in the pressure-diameter relationship relative to arteries cultured with normotensive pressure. The observed differences in the pressure-diameter curves for cultured arteries were due to changes in artery geometry and, in some cases, changes in the arteries’ intrinsic mechanical properties. Relative to freshly isolated arteries, arteries cultured under mechanical conditions similar to in vivo conditions were stiffer, suggesting that aspects of the ex vivo culture other than the mechanical environment also influenced changes in the arteries’ mechanical properties. These results confirm the well-known importance of transmural pressure with regard to arterial wall mechanics while highlighting additional roles for axial stretch in determining mechanical behavior.
Unified Topological Representation Models of Planar Kinematic Chains
Authors: Ding Huafeng , Zhao Jing , Huang Zhen
Published: October 2009

This paper attempts to establish unified topological models and corresponding mathematical representations for planar simple joint, multiple joint, and geared (cam) kinematic chains. First, the conventional topological representation models of kinematic chains are introduced. Then, new topological models of multiple joint and geared (cam) kinematic chains, which are derived from the topological model of simple joint kinematic chains, are presented. The characteristics of the new topological graphs and their associations with the topological graph of simple joint kinematic chains are also addressed. The most important merit of the new topological graphs is that it makes it much easier to undertake unified structure synthesis and further to establish conceptual design platform for various planar mechanisms. Synthesis examples of both multiple joint and geared chains are given, which show the effectiveness of the unified topological models.
Zn-doped CuAlS2 transparent p-type conductive thin films deposited by pulsed plasma deposition
Authors: Yang Ming , Wang Yinghua , Li Guifeng , Shi Zhan , Zhang Qun
Published: October 2009

CuAl 0.90 Zn 0.10 S 2 thin films were deposited by pulsed plasma deposition. The dependence of structural, surface morphology, electrical, and optical properties of the films on substrate temperature was investigated. X-ray diffraction patterns reveal that the film be amorphous structure. The electrical properties are sensitive to the substrate temperature. A typical sample with conductivity of 50.9 S cm−1, carrier mobility of 3.13 cm2 V−1 s−1, carrier concentration of 1.41×1019 cm−3, and average transmission of 74% in visible range of 400–700 nm was obtained. A transparent p-CuAlS2:Zn/n-In2O3:W heterogeneous diode was also fabricated and exhibits rectifying current-voltage characteristics. The ratio of forward current to the reverse current exceeds 80 within the range of applied voltages of −3.0–+3.0 V and the turn-on voltage is approximately 0.5–0.8 V.
Dopamine Gene Therapy for Parkinson’s Disease in a Nonhuman Primate Without Associated Dyskinesia
Authors: Jarraya Béchir , Boulet Sabrina , Scott Ralph G. , Jan Caroline , Bonvento Gilles , Azzouz Mimoun , Miskin James E. , Shin Masahiro , Delzescaux Thierry , Drouot Xavier , Hérard Anne-Sophie , Day Denise M. , Brouillet Emmanuel , Kingsman Susan M. , Hantraye Philippe , Mitrophanous Kyriacos A. , Mazarakis Nicholas D. , Palfi Stéphane
Published: October 2009

A gene therapy approach for the treatment of Parkinson’s disease.
Gene Therapy for Dopamine Replacement in Parkinson´s Disease
Authors: Björklund Anders , Björklund Tomas , Kirik Deniz
Published: October 2009

The introduction of
l
-dopa (
l
-3,4-dihydroxyphenylalanine) therapy 40 years ago was a revolution in the treatment of patients with Parkinson´s disease (PD). With time, however, the shortcomings of oral
l
-dopa medication became apparent, in particular the appearance of troublesome side effects, expressed as involuntary movements (dyskinesias) that developed over time in many patients. A gene therapy approach, aimed at restoring dopamine synthesis in the affected brain by viral vector delivery of genes that encode the dopamine-synthesizing enzymes, may offer a solution to this problem. Now, a team of French and UK researchers reports promising results in a nonhuman primate model of PD, paving the way for clinical trials of this enzyme-replacement approach.
Monitoring Methylation
Authors: McDonald Heather B.
Published: October 2009

A new technique allows digital quantification of rare methylation events, which could serve as cancer biomarkers in clinical samples.
Bacteriophage Cocktail for the Prevention of Biofilm Formation by
Pseudomonas aeruginosa
on Catheters in an
In Vitro
Model System
Authors: Fu Weiling , Forster Terri , Mayer Oren , Curtin John J. , Lehman Susan M. , Donlan Rodney M.
Published: October 2009

Microorganisms develop biofilms on indwelling medical devices and are associated with device-related infections, resulting in substantial morbidity and mortality. This study investigated the effect of pretreating hydrogel-coated catheters with
Pseudomonas aeruginosa
bacteriophages on biofilm formation by
P. aeruginosa
in an
in vitro
model. Hydrogel-coated catheters were exposed to a 10 log
10
PFU ml
−1
lysate of
P. aeruginosa
phage M4 for 2 h at 37°C prior to bacterial inoculation. The mean viable biofilm count on untreated catheters was 6.87 log
10
CFU cm
−2
after 24 h. The pretreatment of catheters with phage reduced this value to 4.03 log
10
CFU cm
−2
(
P
< 0.001). Phage treatment immediately following bacterial inoculation also reduced biofilm viable counts (4.37 log
10
CFU cm
−2
reduction;
P
< 0.001). The regrowth of biofilms on phage-treated catheters occurred between 24 and 48 h, but supplemental treatment with phage at 24 h significantly reduced biofilm regrowth (
P
< 0.001). Biofilm isolates resistant to phage M4 were recovered from catheters pretreated with phage. The phage susceptibility profiles of these isolates were used to guide the development of a five-phage cocktail from a larger library of
P. aeruginosa
phages. The pretreatment of catheters with this cocktail reduced the 48-h mean biofilm cell density by 99.9% (from 7.13 to 4.13 log
10
CFU cm
−2
;
P
< 0.001), but fewer biofilm isolates were resistant to these phages. These results suggest the potential of applying phages, especially phage cocktails, to the surfaces of indwelling medical devices for mitigating biofilm formation by clinically relevant bacteria.
Immune Restoration Diseases Reflect Diverse Immunopathological Mechanisms
Authors: Price Patricia , Murdoch David M. , Agarwal Upasna , Lewin Sharon R. , Elliott Julian H. , French Martyn A.
Published: October 2009

Up to one in four patients infected with human immunodeficiency virus type 1 and given antiretroviral therapy (ART) experiences inflammatory or cellular proliferative disease associated with a preexisting opportunistic infection, which may be subclinical. These immune restoration diseases (IRD) appear to result from the restoration of immunocompetence. IRD associated with intracellular pathogens are characterized by cellular immune responses and/or granulomatous inflammation. Mycobacterial and cryptococcal IRD are attributed to a pathological overproduction of Th1 cytokines. Clinicopathological characteristics of IRD associated with viral infections suggest different pathogenic mechanisms. For example, IRD associated with varicella-zoster virus or JC polyomavirus infection correlate with a CD8 T-cell response in the central nervous system. Exacerbations or de novo presentations of hepatitis associated with hepatitis C virus (HCV) infection following ART may also reflect restoration of pathogen-specific immune responses as titers of HCV-reactive antibodies rise in parallel with liver enzymes and plasma markers of T-cell activation. Correlations between immunological parameters assessed in longitudinal sample sets and clinical presentations are required to illuminate the diverse immunological scenarios described collectively as IRD. Here we present salient clinical features and review progress toward understanding their pathogeneses.
Modern Uses of Electron Microscopy for Detection of Viruses
Authors: Goldsmith Cynthia S. , Miller Sara E.
Published: October 2009

Electron microscopy, considered by some to be an old technique, is still on the forefront of both clinical viral diagnoses and viral ultrastructure and pathogenesis studies. In the diagnostic setting, it is particularly valuable in the surveillance of emerging diseases and potential bioterrorism viruses. In the research arena, modalities such as immunoelectron microscopy, cryo-electron microscopy, and electron tomography have demonstrated how viral structural components fit together, attach to cells, assimilate during replication, and associate with the cellular machinery during replication and egression. These studies provide information for treatment and vaccine strategies.
Towards evidence-based classification in Paralympic athletics: evaluating the validity of activity limitation tests for use in classification of Paralympic running events
Authors: Beckman E M , Tweedy S M
Published: October 2009

Objective:

To classify Paralympic athletes, classifiers use test batteries to obtain an objective, pre-competition estimate of an athlete’s training level. Five tests were evaluated to determine which combination explained the maximum variance in running performance in a non-disabled population. A non-disabled sample was required to permit psychometric evaluation of the tests without the confounding influence of impairment, and to provide an indication of normative performance.

Design:

Sixty-seven non-disabled participants (male and female; mean (SD) age 24.78 (6.53) years) completed a six-test battery comprising a 30 m sprint (criterion activity limitation test) and five supplementary activity limitation tests: standing broad jump, four bounds, 10 m skip, running in place and split jumps.

Results:

Test reliability was high for all tests (intraclass correlations  =  0.80–0.99). Pearson correlations with the 30 m sprint were moderate to strong for standing broad jump (−0.82), four bounds (−0.80) and 10 m skip (0.67), but weaker for split jumps (0.35) and running in place (0.19). Multiple regression indicated that standing broad jump, four bounds and 10 m skip explained 75% of the variance in running performance.

Conclusions:

The test battery is reliable and valid in the non-disabled population and therefore has potential utility in Paralympic classification. Test results were normally distributed, a necessary prerequisite for meaningful interpretation of future studies in athletes with impairments. Further studies evaluating the battery in populations of athletes with impairments of coordination, strength and range of movement are now warranted.
Spawning time variation in Icelandic summer-spawning herring (Clupea harengus)
Authors: Óskarsson Guðmundur J. , Taggart Christopher T.
Published: October 2009

Different fish stocks of the same species are defined by spatial and temporal differences in spawning, though spawning time can vary within and among stocks. Here we address spawning time variation in Icelandic summer-spawning (ISS) Atlantic herring ( Clupea harengus ). We do so by examining influencing factors that include variation in stock size structure, spawning experience (recruit vs. repeat spawners), spawning stock biomass (SSB), sea temperature, and combinations thereof. Our results, based on temporal variation in ovary weight (OW), relative ovary weight (RG), and maturation stage, across a time series of nearly 50 years and eight length classes of ISS herring, show that spawning occurs over a relatively invariant 30-day period defined by day-of-the-year. Logistic regression analyses and temporal development in OW and RG show that maximum spawning invariably occurs on day-of-the-year 200 ± 15 days, and seasonal variation in mesenteric fat content is physiologically consistent with the timing. We show that the smaller recruit spawners tend to spawn ~17 days later, on average, than the larger repeat spawners. Spawning occurs ~7 days later when SSB is greater than the long-term average, and spawning may be delayed by as much as 10 days during periods of colder than average ocean temperature.
Otolith chemistry analyses indicate that water Sr:Ca is the primary factor influencing otolith Sr:Ca for freshwater and diadromous fish but not for marine fish
Authors: Brown Randy J. , Severin Kenneth P.
Published: October 2009

Water chemistry is thought to be the primary factor influencing fish otolith chemistry. Experimental results with freshwater and diadromous fish have been consistent with this paradigm, but with marine fish, they have often been ambiguous or contradictory. A review of water chemistry data indicated that Sr:Ca (mmol:mol) levels were higher in marine water than in most freshwater systems and that Sr:Ca variability was lower in marine water than in most freshwater systems. We therefore hypothesized that lifetime otolith Sr:Ca profiles of freshwater fish would exhibit low levels of Sr:Ca with moderate variability, of diadromous fish would exhibit highly variable Sr:Ca levels, and of marine fish would exhibit high levels of Sr:Ca with low variability. Otolith Sr:Ca profiles from 81 species of freshwater, diadromous, and marine fish revealed that freshwater fish had low levels of Sr:Ca and lower variability than expected relative to marine fish, diadromous fish had Sr:Ca levels and variability that were consistent with expectations, and marine fish had high maximum Sr:Ca levels, as expected, and high Sr:Ca variability, similar in magnitude to diadromous fish, which was not expected. These findings indicate that water Sr:Ca is the primary factor influencing otolith Sr:Ca variation for freshwater and diadromous fish but not for marine fish.
Modelling the distribution of fish accounting for spatial correlation and overdispersion
Authors: Lewy Peter , Kristensen Kasper
Published: October 2009

The spatial distribution of cod ( Gadus morhua ) in the North Sea and the Skagerrak was analysed over a 24-year period using the Log Gaussian Cox Process (LGCP). In contrast to other spatial models of the distribution of fish, LGCP avoids problems with zero observations and includes the spatial correlation between observations. It is therefore possible to predict and interpolate unobserved densities at any location in the area. This is important for obtaining unbiased estimates of stock concentration and other measures depending on the distribution in the entire area. Results show that the spatial correlation and dispersion of cod catches remained unchanged during winter throughout the period, in spite of a drastic decline in stock abundance and a movement of the centre of gravity of the distribution towards the northeast in the same period. For the age groups considered, the concentration of the stock was found to be constant or declining in the period. This means that cod does not follow the theory of density-dependent habitat selection, as the concentration of the stock does not increase when stock abundance decreases.
Hierarchical Bayesian analysis to incorporate age uncertainty in growth curve analysis and estimates of age from length: Florida manatee (Trichechus manatus) carcasses
Authors: Schwarz Lisa K. , Runge Michael C.
Published: October 2009

Age estimation of individuals is often an integral part of species management research, and a number of age-estimation techniques are commonly employed. Often, the error in these techniques is not quantified or accounted for in other analyses, particularly in growth curve models used to describe physiological responses to environment and human impacts. Also, noninvasive, quick, and inexpensive methods to estimate age are needed. This research aims to provide two Bayesian methods to (i) incorporate age uncertainty into an age–length Schnute growth model and (ii) produce a method from the growth model to estimate age from length. The methods are then employed for Florida manatee ( Trichechus manatus ) carcasses. After quantifying the uncertainty in the aging technique (counts of ear bone growth layers), we fit age–length data to the Schnute growth model separately by sex and season. Independent prior information about population age structure and the results of the Schnute model are then combined to estimate age from length. Results describing the age–length relationship agree with our understanding of manatee biology. The new methods allow us to estimate age, with quantified uncertainty, for 98% of collected carcasses: 36% from ear bones, 62% from length.
Temporal trends in probabilistic maturation reaction norms and growth of Atlantic cod (Gadus morhua) on the Icelandic shelf
Authors: Pardoe Heidi , Vainikka Anssi , Thórdarson Gudmundur , Marteinsdóttir Gudrun , Heino Mikko
Published: October 2009

Decreasing temporal trends in probabilistic maturation reaction norm (PMRN) midpoints, symptomatic of earlier maturation despite environmentally induced variation in growth, have been observed in many exploited fish stocks. Here, we studied the growth and maturation trends of female and male Icelandic cod ( Gadus morhua ) by estimating PMRN midpoints for cohorts 1964–1999 and found evidence that a shift towards maturation at smaller sizes and younger ages has occurred independently of changes in growth, condition, and temperature. Weighting the data with regional survey abundance estimates to account for spatial heterogeneity in maturity status and sampling intensity did not qualitatively affect the temporal trends. Length-at-age also decreased through the study period, which, through simulations, could be attributed to the energetic costs of earlier maturity at maturing age groups but not at younger ages. These findings support the hypothesis that such changes in maturation schedules are not caused by environmental factors alone but could also reflect a genetic change, potentially in response to intensive fishing.
Evaluating the demographic significance of genetic homogeneity using a coalescent-based simulation: a case study with gag (Mycteroperca microlepis)
Authors: Cushman Elizabeth L. , Jue Nathaniel K. , Strand Allan E. , Sotka Erik E.
Published: October 2009

Gag ( Mycteroperca microlepis ) from the eastern Gulf of Mexico and northwestern Atlantic are managed as separate stocks, although evidence for their demographic isolation remains equivocal. Several hundred individuals were genotyped at 11 microsatellite loci and it was found that gag across these regions were genetically indistinguishable (FST < 0.001). A coalescent-based computer simulation was employed to quantitatively assess the relative importance of dispersal rate, population size, and time since divergence on gag genetic homogeneity. Using empirical estimates of long-term effective population size (16 500), a range of dispersal rates and divergence times (500 to 500 000 generations) was modeled, and it was concluded that present-day genetic homogeneity must be maintained by dispersal rates of at least 20–30 migrants per generation and up to hundreds or thousands per generation. This study also documents the absence of significant temporal genetic structure and inbreeding in the Atlantic when comparing cohorts separated in time from weeks to 20 years. This suggests that the long-standing practice of overfishing gag has yet to manifest as an inbreeding effect. Overall, gag dispersal rates remain uncertain, and consequently, this study can neither support nor refute management schemes that independently regulate gag in the eastern Gulf of Mexico and northwestern Atlantic.
Production of amylase by soil fungi and partial biochemical characterization of amylase of a selected strain (Aspergillus fumigatus Fresenius)
Authors: Domingues Claudia M. , Peralta Rosane M.
Published: October 2009

Filamentous fungi from soil were screened for their ability to produce amylases in semisolid and liquid media with wheat bran. A selected strain identified as Aspergillus fumigatus Fresenius showed high enzymatic activity for α-amylase and glucoamylase. The maximal yield of these amylases was obtained when lignocellulosic materials were the carbon sources. The optimal pH and temperature were 6.0 and 50 °C, respectively, for both enzymes. α-Amylase activity was more thermostable than glucoamylase activity.Key words: amylolitic fungi, α-amylase, glucoamylase, Aspergillus fumigatus.
Physiological studies with the fungus Entomophaga aulicae during morphogenesis in three different media under fermentation conditions
Authors: Nolan Richard A.
Published: October 2009

The effects of three different media on amino acid uptake and production and glucose and oxygen utilization during protoplast growth and hyphal body production by the fungus Entomophaga aulicae under fermentation conditions were studied. The three media consisted of a basal medium plus either (i) 2.8% fetal calf serum, (ii) 0.8% tryptic soy broth plus 0.4% bovine serum albumin, or (iii) 0.8% tryptic soy broth plus 0.4% calcium caseinate. The protoplasts grew most rapidly (initial peaks on days 2 and 3) and hyphal bodies were detected first (day 3) in the media containing albumin and caseinate. The day 9 hyphal body yields were 3.1 × 107, 7.5 × 108, and 3.1 × 109/10 L in media containing the serum, albumin, and caseinate, respectively. Growth in the albumin and caseinate media also gave the first detectable glucose utilization (days 2 and 3, respectively) and this rapidly increased to 94.9 and 90.6% utilization, respectively, on day 4. Oxygen and glucose utilization were closely related. During protoplast growth prior to hyphal body production, the only common pattern detected was the initial utilization of glutamine in serum- and caseinate-containing media. During the initial period of hyphal body production, cysteic acid, threonine, serine, asparagine, leucine, tyrosine, phenylalanine, and arginine were first utilized and glycine, alanine, and ammonia were first produced in the albumin and caseinate media. At this time (days 3–5), glutamine, proline, cystine, and tryptophan were first utilized and valine and histidine were produced in the albumin medium, and methionine was first utilized and cystathionine produced in the caseinate medium. Four main patterns of overall amino acid utilization and production were identified. The delay in major protoplast growth in the basal medium plus fetal calf serum is felt to result from inhibition by free fatty acids in the serum. Protein utilization was not detected and its main function is considered to be enhancement of protoplast stability against fermentation shear forces.Key words: Entomophaga aulicae, physiology, fermentation growth, protoplasts, hyphal bodies.
Substrate specificity of the high-affinity glucose transport system of Pseudomonas aeruginosa
Authors: Wylie John L. , Worobec Elizabeth A.
Published: October 2009

Specificity of the high-affinity glucose transport system of Pseudomonas aeruginosa was examined. At a concentration of [14C]glucose near the Vmax of the system, inhibition by maltose, galactose, and xylose was detected. This inhibition is similar to that detected in earlier in vivo studies and correlates with the known specificity of OprB, a glucose-specific porin of P. aeruginosa. At a level of [14C]glucose 100 times lower, only unlabelled glucose inhibited uptake to any extent. This matches the known in vitro specificity of the periplasmic glucose binding protein. These findings were used to explain the discrepancy between earlier in vivo and in vitro results reported in the literature.Key words: Pseudomonas aeruginosa, glucose transport, OprB, glucose binding protein.
MONOIDS PRESENTED BY REWRITING SYSTEMS AND AUTOMATIC STRUCTURES FOR THEIR SUBMONOIDS
Authors: CAIN ALAN J.
Published: October 2009

This paper studies rr-, ℓr-, rℓ-, and ℓℓ-automatic structures for finitely generated submonoids of monoids presented by confluent rewriting system that are either finite and special or regular and monadic. A new technique is developed that uses an automaton to "translate" between words in the original rewriting system and words over the generators for the submonoid. This is applied to show that the submonoid inherits any notion of automatism possessed by the original monoid. Generalizations of results of Otto and Ruškuc are thus obtained: every finitely generated submonoid of a monoid presented by a confluent finite special rewriting system admits an automatic structure that is simultaneously rr-, ℓr-, rℓ-, and ℓℓ-automatic; and every finitely generated submonoid of a monoid presented by a confluent regular monadic rewriting system admits an automatic structure that is simultaneously rr- and ℓℓ-automatic. These structures are shown to be effectively computable. An algorithm is given to decide whether the monoid presented by a confluent monadic finite rewriting system is ℓr- or rℓ-automatic. Finally, these results are applied to yield answers to some hitherto open questions and to recover and generalize established results.
Cretaceous felsic volcanism in New Zealand and Lord Howe Rise (Zealandia) as a precursor to final Gondwana break-up
Authors: Tulloch A. J. , Ramezani J. , Mortimer N. , Mortensen J. , van den Bogaard P. , Maas R.
Published: October 2009

We report new, highly precise, U–Pb and Ar/Ar ages for seven Cretaceous rhyolites, tuffs and granites from across Zealandia spanning a 30 Ma period from arc magmatism to continental break-up. Combined with previously published data, these reveal a strong episodicity in Cretaceous silicic magmatism outside the Median Batholith. 112 Ma tuffs are known only from the Eastern Province in association with a Cretaceous normal fault system. Both 101 and 97 Ma groups of rhyolites and tuffs occur across the entire width and half the length of Zealandia from near the palaeotrench to the continental interior, indicating widespread and effectively instantaneous extension. We attribute an increase in A-type character with time (112–101–97–88–82 Ma) to the progressive thinning of the Zealandia continental crust whereby, with time, there is less opportunity for crustal contamination. Extension directions associated with 101, 97 and 82 Ma magmatism and associated core complex exhumation across Zealandia are all oriented
c.
30° oblique to the margin. These observations suggest Zealandia rifting was controlled by either >83 Ma capture of Zealandia by the Pacific Plate and/or <83 Ma Zealandia–West Antarctica spreading, rather than by laterally migrating triple junctions, slab windows or plume heads.
Frugal path mechanisms
Authors: Archer Aaron , Tardos Éva
Published: October 2009

We consider the problem of selecting a low-cost
s
-
t
path in a graph where the edge costs are a secret, known only to the various economic agents who own them. To solve this problem, Nisan and Ronen applied the celebrated Vickrey-Clarke-Groves (VCG) mechanism, which pays a premium to induce the edges so as to reveal their costs truthfully. We observe that this premium can be unacceptably high. There are simple instances where the mechanism pays Θ(
n
) times the actual cost of the path, even if there is an alternate path available that costs only (1 + ϵ) times as much. This inspires the
frugal path
problem, which is to design a mechanism that selects a path and induces truthful cost revelation, without paying such a high premium.

This article contributes negative results on the frugal path problem. On two large classes of graphs, including those having three node-disjoint
s
-
t
paths, we prove that
no
reasonable mechanism can always avoid paying a high premium to induce truthtelling. In particular, we introduce a general class of
min function
mechanisms, and show that all min function mechanisms can be forced to overpay just as badly as VCG. Meanwhile, we prove that
every
truthful mechanism satisfying some reasonable properties is a min function mechanism.

Our results generalize to the problem of hiring a team to complete a task, where the analog of a path in the graph is a subset of the agents constituting a team capable of completing the task.
Entropy-based bounds for online algorithms
Authors: Pandurangan Gopal , Upfal Eli
Published: October 2009

We focus in this work on an aspect of online computation that is not addressed by standard competitive analysis, namely, identifying request sequences for which nontrivial online algorithms are useful versus request sequences for which all algorithms perform equally poorly. The motivations for this work are advanced system and architecture designs which allow the operating system to dynamically allocate resources to online protocols such as prefetching and caching. To utilize these features, the operating system needs to identify data streams that can benefit from more resources.

Our approach in this work is based on the relation between entropy, compression, and gambling, extensively studied in information theory. It has been shown that in some settings, entropy can either fully or at least partially characterize the expected outcome of an iterative gambling game. Our goal is to study the extent to which the entropy of the input characterizes the expected performance of online algorithms for problems that arise in computer applications. We study bounds based on entropy for three classical online problems---list accessing, prefetching, and caching. Our bounds relate the performance of the best online algorithm to the
entropy
, a parameter intrinsic to characteristics of the request sequence. This is in contrast to the
competitive ratio
parameter of competitive analysis, which quantifies the performance of the online algorithm with respect to an optimal offline algorithm. For the prefetching problem, we give explicit upper and lower bounds for the performance of the best prefetching algorithm in terms of the entropy of the request sequence. In contrast, we show that the entropy of the request sequence alone does not fully capture the performance of online list accessing and caching algorithms.
An improved algorithm for radio broadcast
Authors: Elkin Michael , Kortsarz Guy
Published: October 2009

We show that for every radio network
G
= (
V
,
E
) and source
s
∈
V
, there exists a radio broadcast schedule for
G
of length
Rad
(
G
,
s
) +
O
(√
Rad
(
G
,
s
) ⋅log
2
n
) =
O
(
Rad
(
G
,
s
) + log
4
n
), where
Rad
(
G
,
s
) is the radius of the radio network
G
with respect to the source
s
. This result improves the previously best-known upper bound of
O
(
Rad
(
G
,
s
) + log
5
n
) due to Gaber and Mansour [1995].

For graphs with small genus, particularly for
planar
graphs, we provide an even better upper bound of
Rad
(
G
,
S
) +
O
(√
Rad
(
G
,
s
) ⋅ log
n
+ log
3
n
) =
O
(
Rad
(
G
,
s
) + log
3
n
).
Querying priced information in databases
Authors: Carmo Renato , Feder Tomás , Kohayakawa Yoshiharu , Laber Eduardo , Motwani Rajeev , O'Callaghan Liadan , Panigrahy Rina , Thomas Dilys
Published: October 2009

Query optimization that involves expensive predicates has received considerable attention in the database community. Typically, the output to a database query is a set of tuples that satisfy certain conditions, and, with expensive predicates, these conditions may be computationally costly to verify. In the simplest case, when the query looks for the set of tuples that simultaneously satisfy
k
expensive predicates, the problem reduces to ordering the evaluation of the predicates so as to minimize the time to output the set of tuples comprising the answer to the query. We study different cases of the problem: the
sequential case
, in which a single processor is available to evaluate the predicates, and the
distributed case
, in which there are
k
processors available, each dedicated to a different attribute (column) of the database, and there is no communication cost between the processors.

For the sequential case, we give a simple and fast deterministic
k
-approximation algorithm, and prove that
k
is the best possible approximation ratio for a deterministic algorithm, even if exponential time algorithms are allowed. We also propose a randomized, polynomial time algorithm with expected approximation ratio 1 + √2/2 ≈ 1.707 for
k
= 2, and prove that 3/2 is the best possible expected approximation ratio for randomized algorithms. We also show that given 0 ≤ ε ≤ 1, no randomized algorithm achieves approximation ratio smaller than 1 + ε with probability larger than (1 + ε)/2.

For the distributed case, we consider two different models: the
preemptive model
, in which a processor is allowed to interrupt the evaluation of a predicate, and the
nonpreemptive model
, in which the evaluation of a predicate must be completed once started. We show that
k
is the best possible approximation ratio for a deterministic algorithm, even if exponential time algorithms are allowed. For the preemptive model, we introduce a polynomial time
k
-approximation algorithm. For the nonpreemptive model, we introduce a polynomial time
O
(
k
log
2
k
)-approximation algorithm.
The Role of Temporal Synchrony as a Binding Cue for Visual Persistence in Early Visual Areas: An fMRI Study
Authors: Wong Yvonne J. , Aldcroft Adrian J. , Large Mary-Ellen , Culham Jody C. , Vilis Tutis
Published: October 2009

We examined the role of temporal synchrony—the simultaneous appearance of visual features—in the perceptual and neural processes underlying object persistence. When a binding cue (such as color or motion) momentarily exposes an object from a background of similar elements, viewers remain aware of the object for several seconds before it perceptually fades into the background, a phenomenon known as object persistence. We showed that persistence from temporal stimulus synchrony, like that arising from motion and color, is associated with activation in the lateral occipital (LO) area, as measured by functional magnetic resonance imaging. We also compared the distribution of occipital cortex activity related to persistence to that of iconic visual memory. Although activation related to iconic memory was largely confined to LO, activation related to object persistence was present across V1 to LO, peaking in V3 and V4, regardless of the binding cue (temporal synchrony, motion, or color). Although persistence from motion cues was not associated with higher activation in the MT+ motion complex, persistence from color cues was associated with increased activation in V4. Taken together, these results demonstrate that although persistence is a form of visual memory, it relies on neural mechanisms different from those of iconic memory. That is, persistence not only activates LO in a cue-independent manner, it also recruits visual areas that may be necessary to maintain binding between object elements.