bluuebunny/crossref_metadata_2025 huggingface dataset:
An Age-Dependent Branching Process with Correlations Among Sister Cells
Authors: Crump Kenny S. , Mode J. Charles
Published: April 2006

In this note we consider an age-dependent branching process in which the life-spans of sister cells are correlated as well as the numbers of offspring of sister cells, but otherwise cells live and reproduce independently. One might surmise that in many populations there would be some positive correlation among siblings due to similar characteristics inherited from parents. Data of Powell (1955) seem to corroborate this conjecture. Powell's data indicate that in certain bacterial populations the life-spans of sister cells have significant positive correlations while the correlation between the life-spans of mother and daughter cells is negligible. More recently positive correlations have been observed in cell populations among the life-spans of first cousins and also among second cousins (Kubitschek (1967)). However, the model presented in this note permits correlations only among siblings.
The principle of the diffusion of arbitrary constants
Authors: Barbour Andrew D.
Published: April 2006

Equations are derived describing a central limit type large population approximation for continuous time Markov lattice processes in one or more dimensions, such as are commonly encountered in biological models. A method of solving the equations using only the deterministic solution of the process is explained, and it is extended by the use of a martingale argument to provide more detailed information about the process.
Stochastic approximation for the general epidemic
Authors: Ludwig Donald
Published: April 2006

A system of equations is introduced whose solutions are remarkably close to corresponding solutions of the “general stochastic epidemic”. If N is the population size, then there are approximately equations to be solved for the general stochastic epidemic while the number of equations in the approximating system is proportional to N. An asymptotic approximation to the general stochastic epidemic is also introduced. Numerical comparisons of the stochastic and asymptotic approximations with the exact solution are presented.
On a recurrence of Steck
Authors: Breth M.
Published: April 2006

This paper contains a simple proof of Steck's recurrence equation for determining the power of the standard one-sided Kolmogorov test for a distribution function.
Un théorème d'unicité pour les hyperplans poissoniens
Authors: Matheron G.
Published: April 2006

A stationary Poisson process of hyperplanes in Rn is characterized (up to an equivalence) by the function θ such that θ(s) is the density of the Poisson point process induced on the straight lines with direction s. The set of these functions θ is a convex cone ℛ1, a basis of which is a simplex Θ, and a given function θ belongs to ℛ1 if and only if it is the supporting function of a symmetrical compact convex set which is a finite Minkowski sum of line segments or the limit of such finite sums. Another application is given concerning the tangential cone at h = 0 of a coveriance function.
The inverse problem in reducible Markov chains
Authors: Ray W. D. , Margo F.
Published: April 2006

The equilibrium probability distribution over the set of absorbing states of a reducible Markov chain is specified a priori and it is required to obtain the constrained sub-space or feasible region for all possible initial probability distributions over the set of transient states. This is called the inverse problem. It is shown that a feasible region exists for the choice of equilibrium distribution. Two different cases are studied: Case I, where the number of transient states exceeds that of the absorbing states and Case II, the converse. The approach is via the use of generalised inverses and numerical examples are given.
Extinction of non-homogeneous Galton-Watson processes
Authors: Jirina Miloslav
Published: April 2006

In the paper the problem of the extinction of non-homogeneous Galton-Watson processes with one type of particle is studied. It is proved that the process becomes extinct if the expectations of the process do not converge to a limit (finite or infinite). If the expectations have a finite limit, then simple necessary and sufficient conditions for the extinction are proved. The general case remains open; however two more sufficient conditions which are also necessary under some restrictions are given.
A modified random walk in the presence of partially reflecting barriers
Authors: Dua Saroj , Khadilkar Shobha , Sen Kanwar
Published: April 2006

The paper deals with the one-dimensional modified random walk in the presence of partially reflecting barriers at a and –b (a, b > 0). The simple one-dimensional random walk on a line is the motion-record of a particle which may extend over (–∞, + ∞) or be restricted to a portion of it by absorbing and/or reflecting barriers. Here we introduce the possibility of a particle staying put along with its moving a unit step to the right or to the left and find the bivariate generating functions of the probabilities of a particle reaching m (0 <m <a) under different conditions.
A model for interaction of a Poisson and a renewal process and its relation with queuing theory
Authors: Råde Lennart
Published: April 2006

This paper discusses the response process when a Poisson process interacts with a renewal process in such a way that one or more points of the Poisson process eliminate a random number of consecutive points of the renewal process. A queuing situation is devised such that the c.d.f. of the length of the busy period is the same as the c.d.f. of the length of time intervals of the renewal response process. The Laplace-Stieltjes transform is obtained and from this the expectation of the time intervals of the response process is derived. For a special case necessary and sufficient conditions for the response process to be a Poisson process are found.
A branching process showing a phase transition
Authors: Moore T. , Snell J. L.
Published: April 2006

It is shown that a phase transition for the Ising model on a tree graph can be detected by the limiting behavior of the magnetization. The relevant limit theorems are special cases of limit theorems for multitype branching processes.
Exponential ergodicity in Markovian queueing and dam models
Authors: Tuominen Pekka , Tweedie Richard L.
Published: April 2006

We investigate conditions under which the transition probabilities of various Markovian storage processes approach a stationary limiting distribution π at an exponential rate. The models considered include the waiting time of the M/G/1 queue, and models for dams with additive input and state-dependent release rule satisfying a ‘negative mean drift' condition. A typical result is that this exponential ergodicity holds provided the input process is ‘exponentially bounded'; for example, in the case of a compound Poisson input, a sufficient condition is an exponential bound on the tail of the input size distribution. The results are proved by comparing the discrete-time skeletons of the Markov process with the behaviour of a random walk, and then showing that the continuous process inherits the exponential ergodicity of any of its skeletons.
Further results of replacement problem of a parallel system in random environment
Authors: Nakagawa Toshio
Published: April 2006

We have recently discussed the replacement problem of a parallel system in a random environment. This paper extends the same replacement problem for the following two cases which are more plausible: (i) The probability that an operating component fails by the j th shock depends on the number j. (ii) The replacement cost is a linear function of failed components. The expected cost of the above model is obtained. A numerical example is finally presented when the probability of failure time of a component is a negative binomial distribution.
Dynamic investment strategies for a risky R and D project
Authors: Deshmukh S. D. , Chikte S. D.
Published: April 2006

During the course of an R and D project, it is often meaningful and possible to evaluate its status, so that this information may be used for making better financing decisions over time. The project status changes stochastically due to the internal (technological) and the external (market) uncertainties, the former being partially controlled by expenditure of resources. In addition to the resource expenditure strategy, the manager must also decide when to terminate the project. Once the project is terminated, a terminal return is collected, whose value depends on the final project status. It is shown that the project should be terminated if the current status is either too low or too high to make further expenditure worthwhile. Otherwise, for an intermediate (promising) status of the project, an aggressive investment strategy is shown to be optimal. Thus, the model unifies the problems of optimally undertaking, financing and terminating an R and D project in face of various uncertainties.
Another look at the finite mean supercritical Bienaymé–Galton–Watson process
Authors: Cohn Harry
Published: April 2006

Let {Zn} be a finite mean supercritical Bienaymé– Galton–Watson process. It is known that there exist norming constants {Cn} such that {Zn/Cn} converges almost surely to a limit W. Also there is a whole literature concerning properties of {Cn} and W. We attempt a new approach to the limit theory of {Zn} by relating it to the theory of sums of independent and identically distributed random variables.
Polygons formed by random lines in a plane: some further results
Authors: Tanner J. C.
Published: April 2006

Expressions are derived for the third and fourth moments of the distribution of the numbers of sides of the polygons formed by random lines in a plane. These are evaluated numerically; it seems unlikely that they can be expressed simply in terms of elementary functions or constants. Using these results, the third and fourth moments of the distribution of the perimeters of the polygons are derived.
Partial balance and insensitivity
Authors: Whittle P.
Published: April 2006

A direct and general proof is given of the equivalence of partial balance and insensitivity.
The slow server problem
Authors: Rubinovitch Michael
Published: April 2006

The problem is what to do with a slow server in a service facility which has fast and slow servers. Should the slow server be used to render service, or is it better not to use it at all? Simple models for answering this question are formulated and studied.
On non-singular Markov renewal processes with an application to a growth–catastrophe model
Authors: Niemi Seppo
Published: April 2006

The paper is concerned with Markov renewal processes satisfying a certain non-singularity condition. The relation of this condition to irreducibility, Harris recurrence and regularity of the associated forward Markov process is studied. This enables one to prove limit theorems of a total variation type for Markov renewal processes and semi-regenerative processes by applying Orey's theorem to the forward process. The results are applied to a GI/G/1 queue and a growth-catastrophe population model.
A limiting distribution for Bernoulli trials with second-order Markov dependence
Authors: Brainerd Barron
Published: April 2006

Let ℰ be an event governed by a homogeneous second-order two-state Markov chain. Assume the steady state has been achieved. Consider Nm the number of times that ℰ occurs in m successive trials. The limiting distribution of P(Nm = k) is obtained under the condition that mP(ℰ)=λ.
Limit theorems for some sequential occupancy problems
Authors: Janson Svante
Published: April 2006

Consider n cells into which balls are thrown at random until all but m cells contain at least l + 1 balls each. Asymptotic results when n →∞, m and l held fixed, are given for the number of cells containing exactly k balls and for related random variables.
Sampling random polygons
Authors: George Edward I.
Published: April 2006

Every realization of a Poisson line process is a set of lines which subdivides the plane into a population of non-overlapping convex polygons. To explore the unknown statistical features of this population, an alternative stochastic construction of random polygons is developed. This construction, which is based on an alternating sequence of random angles and side lengths, provides a fast simulation method for obtaining a random sample from the polygon population. For the isotropic case, this construction is used to obtain a random sample of 2500000 polygons, providing the most precise estimates to date of some of the unknown distributional characteristics.
Parameter estimation for finite-parameter stationary random fields
Authors: Rosenblatt M.
Published: April 2006

The concept of strong mixing is used to obtain a generalization of results on the asymptotic distribution of finite-parameter estimates of linear processes and extend them for stationary sequences and random fields.
Networks of non-homogeneous M/G/∞ systems
Authors: Keilson J. , Servi L. D.
Published: April 2006

For a network of G/∞ service facilities, the transient joint distribution of the facility populations is shown by new simple methods to have a simple Poisson product form with simple explicit formulas for the means. In the network it is assumed that: (a) each facility has an infinite number of servers; (b) the service time distributions are general; (c) external traffic is non-homogeneous in time; (d) arrivals have random or deterministic routes through the network possibly returning to the same facility more than once; (e) arrivals use the facilities on their route sequentially or in parallel (as in the case of a circuitswitched telecommunication network). The results have relevance to communication networks and manufacturing systems.
Rate modulation in dams and ruin problems
Authors: Asmussen Søren , Kella Offer
Published: April 2006

We consider a dam in which the release rate depends both on the state and some modulating process. Conditions for the existence of a limiting distribution are established in terms of an associated risk process. The case where the release rate is a product of the state and the modulating process is given special attention, and in particular explicit formulas are obtained for a finite state space Markov modulation.
An extended class of time-continuous branching processes
Authors: Chen Rong-Rong
Published: April 2006

This paper is devoted to studying an extended class of time-continuous branching processes, motivated by the study of stochastic control theory and interacting particle systems. The uniqueness, extinction, recurrence and positive recurrence criteria for the processes are presented. The main new point in our proofs is the use of several different comparison methods. The resulting picture shows that the methods are effective and hence should also be meaningful in other situations.
A correspondence between product-form batch-movement queueing networks and single-movement networks
Authors: Coleman J. L. , Henderson W. , Pearce C. E. M. , Taylor P. G.
Published: April 2006

A number of recent papers have exhibited classes of queueing networks, with batches of customers served and routed through the network, which have generalised product-form equilibrium distributions. In this paper we look at these from a new viewpoint. In particular we show that, under standard assumptions, for a network to possess an equilibrium distribution that factorises into a product form over the nodes of the network for all possible transition rates, it is necessary and sufficient that it be equivalent to a suitably-defined single-movement network. We consider also the form of the state space for such networks.
Optimal software release policy based on a two-person game of timing
Authors: Zeephongsekul P. , Chiera C.
Published: April 2006

This paper presents a software release policy based on a two-person game of timing. Existing release policies depend solely on cost factors and ignore the element of competition between rival producers, whereas in our policy both of these factors are taken into consideration. Through a series of preliminary results, it is shown that an optimal release policy exists as a Nash equilibrium point in the space of mixed strategies. We also present numerical examples of this optimal policy applied to software reliability growth models which are based on the non-homogeneous Poisson process.
Evaluation of β-Cell Replication in Mice Transgenic for Hepatocyte Growth Factor and Placental Lactogen
Authors: Cozar-Castellano Irene , Weinstock Matthew , Haught Marcia , Velázquez-Garcia Silvia , Sipula Darinka , Stewart Andrew F.
Published: April 2006

We hypothesized that combined transgenic overexpression of hepatocyte growth factor (HGF) and placental lactogen in islets would lead to even greater increases in β-cell mass and replication than either growth factor alone. This did not occur, suggesting that β-cell replication is saturable or subject to molecular restraint. We therefore performed the first comprehensive G1/S cell cycle survey in islets, cataloguing the broad range of kinases, cyclins, and kinase inhibitors that control the G1/S transition in islets from normal, HGF, placental lactogen, and doubly transgenic mice. Many of the G1/S checkpoint regulators (E2Fs; pRb; p107; p130; cyclins D1,2,3, A, and E; cdk-2; cdk-4; p15; p16; p18; p19; p21; p27; MDM2; p53; c-Myc; and Egr-1) are present in the murine islet. Most of these proteins were unaltered by overexpression of HGF or placental lactogen, either alone or in combination. In contrast, p21cip was uniquely, dramatically, and reproducibly upregulated in placental lactogen and HGF islets. p21cip was also present in, and upregulated in, proliferating human islets, localizing specifically in β-cells and translocating to the nucleus on mitogenic stimulation. Homozygous p21cip loss releases islets from growth inhibition, markedly enhancing proliferation in response to HGF and placental lactogen.
Noninvasive Diagnosis of Focal Hyperinsulinism of Infancy With [18F]-DOPA Positron Emission Tomography
Authors: Otonkoski Timo , Näntö-Salonen Kirsti , Seppänen Marko , Veijola Riitta , Huopio Hanna , Hussain Khalid , Tapanainen Päivi , Eskola Olli , Parkkola Riitta , Ekström Klas , Guiot Yves , Rahier Jacques , Laakso Markku , Rintala Risto , Nuutila Pirjo , Minn Heikki
Published: April 2006

Congenital hyperinsulinism of infancy (CHI) is characterized by severe hypoglycemia due to dysregulated insulin secretion, associated with either focal or diffuse pathology of the endocrine pancreas. The focal condition is caused by a paternally inherited mutation in one of the genes encoding the subunits of the β-cell ATP-sensitive potassium channel (SUR1/ABCC8 or Kir6.2/KCNJ11) and somatic loss of maternal 11p15 alleles within the affected area. Until now, preoperative diagnostics have relied on technically demanding and invasive catheterization techniques. We evaluated the utility of fluorine-18 l-3,4-dihydroxyphenylalanine ([18F]-DOPA) positron emission tomography (PET) to identify focal pancreatic lesions in 14 CHI patients, 11 of which carried mutations in the ABCC8 gene (age 1–42 months). To reduce bias in PET image interpretation, quantitative means for evaluation of pancreatic [18F]-DOPA uptake were established. Five patients had a visually apparent focal accumulation of [18F]-DOPA and standardized uptake value (SUV) >50% higher (mean 1.8-fold) than the maximum SUV of the unaffected part of the pancreas. When these patients were operated on, a focus of 4–5 × 5–8 mm matching with the PET scan was found, and all were normoglycemic after resection of the focus. The remaining nine patients had diffuse accumulation of [18F]-DOPA in the pancreas (SUV ratio <1.5). Diffuse histology was verified in four of these, and pancreatic catheterization was consistent with diffuse pathology in four cases. In conclusion, [18F]-DOPA PET is a promising noninvasive method for the identification and localization of the focal form of CHI.
Evidence for metabolic and reproductive phenotypes in mothers of women with polycystic ovary syndrome
Authors: Sam Susan , Legro Richard S. , Essah Paulina A. , Apridonidze Teimuraz , Dunaif Andrea
Published: April 2006

Dyslipidemia is a feature of polycystic ovary syndrome (PCOS), but its pathogenesis remains controversial. We performed this study of mothers of women with PCOS to test the hypothesis that dyslipidemia is a heritable trait in families of women with PCOS and to investigate the impact of age on reproductive and metabolic phenotypes. Fasting blood was obtained in 215 non-Hispanic white mothers of women with PCOS and 62 control women. The prevalence of metabolic syndrome was compared with that in non-Hispanic white women of comparable age from the National Health and Nutrition Examination Survey III. Mothers had higher total (
P
< 0.001) and low-density lipoprotein (LDL) cholesterol levels (
P
= 0.007), whereas high-density lipoprotein and triglyceride levels did not differ compared with control women. The only predictors of LDL levels in mothers were their daughters’ LDL levels (
r
2
= 0.11,
P
< 0.001) and their own unbound testosterone levels (
r
2
= 0.04,
P
= 0.03). The prevalence of metabolic syndrome was increased in obese (body mass index ≥ 30 kg/m
2
) mothers compared with obese non-Hispanic white women from the National Health and Nutrition Examination Survey III (
P
= 0.04). Thirty-one percent of mothers reported a history of menstrual irregularity. These mothers had higher androgen levels, markers of insulin resistance, and LDL levels than mothers with regular menses. LDL levels are increased in mothers of women with PCOS, suggestive of a heritable trait. A history of menstrual irregularity identifies mothers with features of PCOS. Obese mothers have a very high prevalence of metabolic syndrome. These findings suggest that both the reproductive and metabolic abnormalities persist with age in PCOS.
Regulating Antarctic Tourism and the Precautionary Principle
Authors: Bastmeijer Kees , Roma Ricardo
Published: April 2006

Antarctic tourism is a rapidly growing industry. From 1958 until 1987, an average of fewer than 1000 tourists visited Antarctica each season. In the 1993-1994 season, the tourists visiting Antarctica outnumbered the scientists for the first time. In recent years (1999-2003), between 13,000 and 15,000 tourists made landings in Antarctica, and during the last season (2003-2004) this number increased by 45 percent to more than 19,500 (see figure 1, p. 764). The estimate of total passengers for the 2003-2004 season, including those not landing, is over 27,000.
The ICJ Advisory Opinion on the Israeli Security Fence and the Limits of Self-Defense
Authors: Wedgwood Ruth
Published: April 2006

On December 8, 2003, the International Court of Justice was requested by the United Nations General Assembly to give an advisory opinion on the “legal consequences” of the security fence under construction by Israel in the West Bank, also variously called “security barrier” and “wall.” The General Assembly sought referral to the Court by a vote of 90 states—but another 74 states abstained, and 8 states voted in opposition. Careful consideration of the case was rendered especially difficult by the decision of the Court to set a truncated briefing schedule, permitting only six weeks for written submissions on jurisdiction and the merits. An even greater concern was the danger, perhaps realized, that the Court’s opinion might be read as prejudging issues central to negotiations in the “Roadmap” political process seeking peace in the Middle East. The hope for some coherence in the approach of the international community to the resolution of a difficult and violent conflict is not otiose, especially where a stable settlement will require ongoing diplomatic, economic, and security support. For that very reason, two of the road map’s sponsors—the United States and the Russian Federation—urged the Court to take account of the impact that any decision might have on the negotiating process. The European Union, as a third member of the “Quartet” sponsoring the road map, together with the ten acceding states to the European Union and fifteen other states, urged the Court to decline to render any advisor)’ opinion at all because of the “compelling” circumstances of the peacemaking process.
Interleukin-7 Is a Survival Factor for CD4+ CD25+ T-Cells and Is Expressed by Diabetes-Suppressive Dendritic Cells
Authors: Harnaha Jo , Machen Jennifer , Wright Marietta , Lakomy Robert , Styche Alexis , Trucco Massimo , Makaroun Sami , Giannoukakis Nick
Published: April 2006

Dendritic cells can facilitate allograft survival and prevent autoimmunity via direct and indirect cell-mediated mechanisms. Recent studies demonstrate that immunoregulatory dendritic cells (iDCs) confer immune hyporesponsiveness in part through CD4+ CD25+ T regulatory cells (Tregs). Herein, we provide evidence to support the hypothesis that dendritic cells derived from NOD mice and engineered ex vivo to exhibit suppressed expression of the CD40, CD80, and CD86 costimulatory molecules motivate an increase in the prevalence of regulatory CD4+ CD25+ T-cells via interleukin (IL)-7. Unlike control dendritic cells, these dendritic cells expressed significant levels of IL-7. Exogenous addition of IL-7 to NOD T-cells did not promote expansion or proliferation, but instead selectively maintained the number of CD4+ CD25+ T-cells by inhibiting activation of apoptosis in these cells. In vitro, IL-7 receptor α-chain (IL-7Rα) was expressed at significantly higher levels on CD4+ CD25+ T-cells compared with CD4+ CD25− T-cells irrespective of resting or stimulated state. In vivo, CD4+ CD25+ T-cells obtained from NOD-scid mice reconstituted with ex vivo engineered iDCs and NOD splenocytes expressed significantly higher levels of IL-7Rα compared with levels in the CD4+ CD25− subset, especially in diabetes-suppressive dendritic cell–administered NOD-scid recipients. Taken together, our data suggest a novel mechanism by which iDCs delay autoimmunity through the CD4+ CD25+ Treg pathway and suggest IL-7 as a survival factor for these putative Tregs, which express the α-chain of its receptor at considerably higher levels than CD4+ CD25− T-cells.
Seasonal variation in trawl codend selection of northern North Sea haddock
Authors: Özbilgin H. , Ferro R.S.T. , Robertson J.H.B. , Holtrop G. , Kynoch R.J.
Published: April 2006

We investigate the variation in three separate months of trawl codend size selection for haddock, paying attention to changes in the length/girth relationship, and size of the total catch in the codend. Three cruises were conducted on the same fishing grounds using the same fishing gear on board the same commercial trawler in April 1995, September 1995, and February 1996. The periods coincided with postspawning in April, post-summer feeding in September, and prespawning in February. The seawater temperature at the seabed on the fishing grounds was near its annual maximum in September (12.2°C) and annual minimum in February (7.2°C) and in April (7°C). There was significant variation in selectivity of haddock with month and total catch in the codend. Fish length and, for two of the three cruises, fish maximum girth were used as variables in selectivity analysis. The probability of being retained was lowest in September, when the fish were in good condition and water temperature was highest, but girth was also largest (50% retention length L50 = 33.5 cm; girth at L50 = 172 mm). The retention probability was intermediate in February when the water was cold and the fish were prespawning, again with relatively large girths (L50 = 31.3 cm; girth at L50 = 158 mm). The retention probability was highest in April when the fish were postspawning, the water was cold, and the fish had the smallest girth (L50 = 27.3 cm; girth at L50 = 129 mm). Although care was taken to maintain similar conditions during all trips, there were some differences between April and the other months. Overall, retention was not related simply to girth and length. In September and February, at constant girth, codend retention increased with length, suggesting that within a given month, fish condition has an effect on selectivity. However, at constant length an increase in girth in February led to an increase in retention, but in September to a decrease in retention. A possible explanation is that, in February, the girth of a fish increases owing to its sexual maturity, whereas in September, increased girth is due to maximum volume of somatic tissue. Water temperature and volume of fish muscle affect the maximum rate and power of swimming. Swimming ability may be a significant factor in determining selectivity.
Power line harmonic radiation (PLHR) observed by the DEMETER spacecraft
Authors: Němec F. , Santolík O. , Parrot M. , Berthelier J. J.
Published: April 2006

Results of a systematic survey of Power Line Harmonic Radiation (PLHR) observed by a recently (June 2004) launched French spacecraft DEMETER are presented. In order to obtain a statistically significant number of events, an automatic identification procedure has been developed and all the available high‐resolution data have been processed. Altogether, 58 events have been found in 865 hours of data recorded during the first year of operation. These events form three different classes: with frequency spacing of spectral lines of 50/100 Hz (10 events), with frequency spacing of 60/120 Hz (13 events), with other spacings/not clear cases (35 events). The first two classes of events are discussed in detail, showing that their origin is most probably connected with the radiation from the electric power systems which are magnetically conjugated with the place of observation. Additionally, in more than one half of the cases, the frequencies of PLHR lines well corresponded to the multiples of the power system frequency. The frequency drift of all the observed events was very slow, if observable. The events occurred without any significant preference for low or high geomagnetic activity, although more intense events were observed during disturbed times. Simultaneous observations of electric and magnetic components of PLHR suggest that the waves propagate in the electromagnetic right‐hand polarized whistler mode.
Large-Scale Analysis of mRNA Translation States during Sucrose Starvation in Arabidopsis Cells Identifies Cell Proliferation and Chromatin Structure as Targets of Translational Control
Authors: Nicolaï M. , Roncato M.A. , Canoy A.S. , Rouquié D. , Sarda X. , Freyssinet G. , Robaglia C.
Published: April 2006

Sucrose starvation of Arabidopsis (Arabidopsis thaliana) cell culture was used to identify translationally regulated genes by DNA microarray analysis. Cells were starved by subculture without sucrose, and total and polysomal RNA was extracted between 6 and 48 h. Probes were derived from both RNA populations and used to screen oligonucleotide microarrays. Out of 25,607 screened genes, 224 were found to be differentially accumulated in polysomal RNA following starvation and 21 were found to be invariant in polysomal RNA while their total RNA abundance was modified. Most of the mRNA appears to be translationally repressed (183/245 genes), which is consistent with a general decrease in metabolic activities during starvation. The parallel transcriptional analysis identifies 268 regulated genes. Comparison of transcriptional and translational gene lists highlights the importance of translational regulation (mostly repression) affecting genes involved in cell cycle and cell growth, these being overrepresented in translationally regulated genes, providing a molecular framework for the arrest of cell proliferation following starvation. Starvation-induced translational control also affects chromatin regulation genes, such as the HD1 histone deacetylase, and the level of histone H4 acetylation was found to increase during starvation. This suggests that regulation of the global nuclear transcriptional activity might be linked to cytoplasmic translational regulations.
Effects of Ferric Hydroxide on Methanogenesis from Lipids and Long‐Chain Fatty Acids in Anaerobic Digestion
Authors: Li Zhengkai , Wrenn Brian A. , Venosa Albert D.
Published: April 2006

The addition of ferric hydroxide to sludge from a municipal anaerobic digester stimulated the rate of methanogenesis from canola oil when the initial oil concentration was high (4600 mg/L; P < 0.002), but not when it was low (920 mg/L; P > 0.05). Similar trends were observed when oleic acid, a fatty acid that is a major component of canola oil triglycerides, was provided, but the effects were statistically significant only when the initial concentration of ferric hydroxide was also high (18 g/L; P = 0.015). Iron reduction occurred when ferric hydroxide was added to microcosms containing anaerobic digester sludge, but the extent of ferrous iron production was much less in acetate‐amended microcosms than in those that were provided with canola oil or oleic acid. Methanogenesis and acetate consumption were completely inhibited when the initial acetate concentration was approximately 5000 mg/L, regardless of the initial ferric hydroxide concentration. The main effect of ferric hydroxide in this system appears to have been a result of stimulation of the rate of fatty acid oxidation.
Beneficial and perverse effects of isoniazid preventive therapy for latent tuberculosis infection in HIV–tuberculosis coinfected populations
Authors: Cohen Ted , Lipsitch Marc , Walensky Rochelle P. , Murray Megan
Published: April 2006

In sub-Saharan Africa, where the emergence of HIV has caused dramatic increases in tuberculosis (TB) case notifications, new strategies for TB control are necessary. Isoniazid preventive therapy (IPT) for HIV–TB coinfected individuals reduces the reactivation of latent
Mycobacterium tuberculosis
infections and is being evaluated as a potential community-wide strategy for improving TB control. We developed a mathematical model of TB/HIV coepidemics to examine the impact of community-wide implementation of IPT for TB–HIV coinfected individuals on the dynamics of drug-sensitive and -resistant TB epidemics. We found that community-wide IPT will reduce the incidence of TB in the short-term but may also speed the emergence of drug-resistant TB. We conclude that community-wide IPT in areas of emerging HIV and drug-resistant TB should be coupled with diagnostic and treatment policies designed to identify and effectively treat the increasing proportion of patients with drug-resistant TB.
Virus-Induced Gene Silencing of Argonaute Genes in Nicotiana benthamiana Demonstrates That Extensive Systemic Silencing Requires Argonaute1-Like and Argonaute4-Like Genes
Authors: Jones Louise , Keining Teresa , Eamens Andrew , Vaistij Fabián E.
Published: April 2006

Several distinct pathways of RNA silencing operate in plants with roles including the suppression of virus accumulation, control of endogenous gene expression, and direction of DNA and chromatin modifications. Proteins of the Dicer-Like and Argonaute (AGO) families have key roles within these silencing pathways and have distinct biochemical properties. We are interested in the relationships between different silencing pathways and have used Nicotiana benthamiana as a model system. While not being an amenable plant for traditional genetics, N. benthamiana is extensively used for RNA-silencing studies. Using virus-induced gene silencing technology we demonstrate that both NbAGO1- and NbAGO4-like genes are required for full systemic silencing but not for silencing directed by an inverted repeat transgene. Phenotypic differences between the virus-induced gene silencing plants indicate that NbAGO1 and NbAGO4 like act at different stages of the silencing pathways. Suppression of NbAGO1 expression recapitulated the hypomorphic mutant phenotype of certain Arabidopsis (Arabidopsis thaliana) ago1 alleles, however, suppression of NbAgo4 like resulted in phenotypes differing in some respects from those reported for Arabidopsis ago4. We suggest that the small interfering RNA amplification step required for full systemic silencing is dependent upon a nuclear event requiring the activity of NbAGO4 like.
Evidence for K+-Dependent HCO3− Utilization in the Marine Diatom Phaeodactylum tricornutum
Authors: Chen Xiongwen , Qiu C.E. , Shao J.Z.
Published: April 2006

Photosynthetic utilization of inorganic carbon in the marine diatom Phaeodactylum tricornutum was investigated by the pH drift experiment, measurement of K1/2 values of dissolved inorganic carbon (DIC) with pH change, and comparison of the rate of photosynthesis with the rate of the theoretical CO2 formation from uncatalyzed HCO3− conversion in the medium. The higher pH compensation point (10.3) and insensitivity of the photosynthetic rate to acetazolamide indicate that the alga has good capacity for direct HCO3− utilization. The photosynthetic rate reached 150 times the theoretical CO2 supply rate at 100 μmol L−1 DIC (pH 9.0) in the presence of 10 mmol L−1 K+ and 46 times that in the absence of K+, indicating that for pH 9.4-grown P. tricornutum, HCO3− in the medium is taken up through K+-dependent and -independent HCO3− transporters. The K1/2 (CO2) values at pH 8.2 were about 4 times higher than those at pH 9.0, whereas the K1/2 (HCO3−) values at pH 8.2 were slightly lower than those at pH 9.0 whether without or with K+, providing further evidence for the presence of the two HCO3− transport patterns in this alga. Photosynthetic rate and affinity for HCO3− in the presence of K+, respectively, were about 2- and 7-fold higher than those in the absence of K+, indicating that K+-dependent HCO3− transport is a predominant pattern of HCO3− cellular uptake in low DIC concentration. However, as P. tricornutum was cultured at pH 7.2 or 8.0, photosynthetic affinities to HCO3− were not affected by K+, implying that K+-dependent HCO3− transport is induced when P. tricornutum is cultured at high alkaline pH.
Nonprosecutorial Sanctions for Grave Violations of International Humanitarian Law: Wartime Conduct of Bosnian Police Officials
Authors: Naarden Gregory L.
Published: April 2006

Addressing accountability for human rights atrocities takes on particular significance in postconflict situations. To the extent that mechanisms for accountability facilitate the pursuit of justice against individual perpetrators, the reform of institutions staffed by perpetrators, and the initiation of reconciliation processes, identifying those who committed atrocities is a fundamental aspect of a peacekeeping mission.

The international community has established tribunals to try those who committed atrocities and will not be tried in domestic courts. Such tribunals, however, limit the scope of prosecutions to high-ranking officials, and do not command sufficient resources to pursue the multitude of individuals who participated in atrocities. Domestic courts have jurisdiction to try individuals who participated in atrocities, but judicial systems in postconflict. countries find themselves in disarray and generally unable to cope with sensitive cases, because of both the subject matter and the potential number of cases.
The 2002 Judicial Activity of the International Court of Justice
Authors: Crook John R.
Published: April 2006

During 2002, countries from all regions, especially Africa, resorted to the International Court of Justice; only one of the Court's 2002 judgments involved an OECD countiy. The Court's work during the year also shows the continued importance of boundary issues for states and for the Court.

The Court again completed a substantial program of work, resolving three cases with final judgments. In February, it triggered substantial controversy by finding that a Belgian court's warrant for the arrest of the then foreign minister of the Democratic Republic of the Congo (“Congo”) violated international law. In October, it resolved a complex of boundary disputes between Cameroon and Nigeria, although by year-end Nigeria had not yet implemented the Court's key requirement—withdrawal from the Bakassi Peninsula. In December, comparing sparse effectivités, it concluded that Malaysia, and not Indonesia, had sovereignty over two small disputed islands.
Sovereignty-Modern: A New Approach to an Outdated Concept
Authors: Jackson John H.
Published: April 2006

Although much criticized, the concept of “sovereignty” is still central to most thinking about international relations and particularly international law. The old “Westphalian” concept in the context of a nation-state’s “right” to monopolize certain exercises of power with respect to its territory and citizens has been discredited in many ways (as discussed below), but it is still prized and harbored by those who maintain certain “realist” views or who otherwise wish to prevent (sometimes withjustification) foreign or international powers and authorities from interfering in a national government’s decisions and activities. Furthermore, when one begins to analyze and disaggregate the concept of sovereignty, it quickly becomes apparent that it has many dimensions. Often, however, the term “sovereignty” is invoked in a context or manner designed to avoid and prevent analysis, sometimes with an advocate’s intent to fend off criticism orjustifications for international “infringements” on the activities of a nation-state or its internal stakeholders and power operators.
International Law Immunities and the International Criminal Court
Authors: Akande Dapo
Published: April 2006

The tension between the protection of human rights and the demands of state sovereignty is reflected in the debate on whether state officials should be held responsible in external fora for international crimes committed while in office. This debate involves the interplay between two branches of international law. Firstly, there is the well-established law according immunities to the state and its agents from the jurisdiction of other states (state and diplomatic immunities). This law proceeds from notions of sovereign equality and is aimed at ensuring that states do not unduly interfere with other states and their agents. On the other hand, there are those newer principles of international law that are based on humanitarian values and define certain types of conduct as crimes under international law (international criminal law). One of the challenges in this latter area has been to develop international and national mechanisms by which individuals who commit these crimes may be held responsible. Since states often fail to institute domestic prosecution of their own officials and agents alleged to have committed international crimes, renewed attention has been paid to the possibility of subjecting state agents to prosecution in foreign domestic courts or in international courts. For such prosecution in foreign domestic courts to take place, it will usually have to be shown (1) that those courts have jurisdiction over crimes committed abroad by foreigners against foreigners (i.e..universalorquasi-universal jurisdiction),and (2) that such jurisdiction extends to state agents (i.e., that international law immunities are unavailable). Recent years have seen a significant increase in attempts to institute prosecutions for alleged international crimes in the national courts of states other than that where the acts occurred. However, it has not proved easy to establish the two propositions identified above. Indeed, it has become apparent that the views that states possess universal jurisdiction over international crimes committed abroad and that incumbent and former state officials are subject to foreign domestic prosecution for such crimes are by no means universally held.
Costimulation Blockade of Both Inducible Costimulator and CD40 Ligand Induces Dominant Tolerance to Islet Allografts and Prevents Spontaneous Autoimmune Diabetes in the NOD Mouse
Authors: Nanji Sulaiman A. , Hancock Wayne W. , Luo Bin , Schur Colleen D. , Pawlick Rena L. , Zhu Lin Fu , Anderson Colin C. , Shapiro A.M. James
Published: April 2006

Costimulation blockade is a promising strategy for preventing allograft rejection and inducing tolerance. Using a fully allogeneic mouse model, we tested the effectiveness of the combined blockade of the CD40 ligand and the inducible costimulator (ICOS) on islet allograft survival and in the prevention of autoimmune diabetes in the NOD mouse. Recipients treated with blocking monoclonal antibodies (mAbs) to ICOS and the CD40 ligand had significant prolongation of graft survival, with 26 of 28 functioning for >200 days. Long-term engrafted mice maintained antidonor proliferative and cytotoxic responses, but donor-specific immunization did not induce graft rejection, and challenge with second, same donor but not third-party grafts resulted in long-term acceptance. The immunohistology of tolerant grafts demonstrated the presence of CD4+CD25+ T-cells expressing Foxp3, and islet/kidney composite grafts from tolerant mice, but not from mice lacking lymphocytes, were accepted indefinitely when transplanted into naïve B6 mice, suggesting that recipient T-cells were necessary to generate dominant tolerance. Combined anti-ICOS and anti–CD40 ligand mAb therapy also prevented diabetes in NOD mice, with only 11% of treated recipients developing diabetes compared with 75% of controls. These data demonstrate that the blockade of CD40 ligand and ICOS signaling induces islet allograft tolerance involving a dominant mechanism associated with intragraft regulatory cells and prevents autoimmune diabetes in NOD mice.
The fishery for pelagic redfish (Sebastes mentella) in the Irminger Sea and adjacent waters
Authors: Sigurðsson Th. , Kristinsson K. , Rätz H-J. , Nedreaas K.H. , Melnikov S.P. , Reinert J.
Published: April 2006

This paper describes the pelagic fishery for deep-sea redfish, Sebastes mentella, in the Irminger Sea and adjacent waters, from the start of commercial exploitation of the resource in 1982. The information prior to 1990 is mostly based on ICES reports and unpublished data, but from 1990, logbook data from a joint database on a haul-by-haul basis from the Faroe Islands, Germany, Greenland, Iceland, Norway, and Russia are used to describe the fishery. The nations listed are the main ones operating on the resource, catching about 80% of the total reported catches in recent years. The logbook data include inter alia information on positions, catch, and trawling time. Additionally, some nations also include information on gear type and size of gear used, and in some cases also trawling depth. Length distributions of commercial catches from various fleets for the whole period have also been collected, and are shown along with information on the mean lengths in the catches for the whole period. The paper therefore provides a detailed overview of the fishery in terms of area, season, depth, and size composition of the catches from the start of the pelagic fishery to the present, allowing better understanding of the behaviour of the fishery and, in turn, providing improved background for assessment of the resource in the future.
A novel joint space‐wavenumber analysis of an unusual Antarctic gravity wave event
Authors: Stockwell R. G. , Taylor M. J. , Nielsen K. , Jarvis M. J.
Published: April 2006

As part of a collaborative research program between British Antarctic Survey, U.K. and Utah State University, USA, all sky airglow images were recorded at Halley Station Antarctica (75.5 S, 26.7 W). An unusual mesospheric gravity wave event was observed in the OH nightglow (nominal height ≈87 km) over a period of ≈3 hours on the 27–28 May, 2001. The characteristics of the bore wave event were determined by application of the one dimensional spatial S‐Transform analysis. This is the first time such analysis has been performed on airglow data. By employing these local spatial spectral analysis, the evolution of the wave packet can be measured. The wave parameters (phase velocity, wave number, wavelength, period) were inferred from as little as 2 images (separated in time), which is a powerful ability when a data set of images is irregularly sampled in time, as is often the case in airglow imager studies. Several interesting and novel results were obtained regarding the dynamic evolution of the wave. The horizontal wavelength of the bore wave packet was seen to decrease as the packet evolved. Coincident with this observation, the horizontal phase speed decreased, with an associated decrease in wave packet amplitude.