Extreme Hypotheses Research Articles

Reassessment of the Null Result of the HST Search for Planets in 47 Tucanae

Abstract We revisit the null result of the Hubble Space Telescope search for transiting planets in the globular cluster 47 Tucanae, in the light of improved knowledge of planet occurrence from the Kepler mission. Gilliland and co-workers expected to find 17 planets, assuming the 47 Tuc stars have close-in giant planets with the same characteristics and occurrence rates as those of the nearby stars that had been surveyed up until 1999. We update this result by assuming that 47 Tuc and Kepler stars have identical planet populations. The revised number of expected detections is . When we restrict the Kepler stars to the same range of masses as the stars that were searched in 47 Tuc, the number of expected detections is reduced to . Thus, the null result of the HST search is less statistically significant than it originally seemed. We cannot reject even the extreme hypothesis that 47 Tuc and Kepler stars have the same planet populations, with more than 2–3σ significance. More sensitive searches are needed to allow for comparisons between the planet populations of globular clusters and field stars.

The influence of thermal tolerances on geographical ranges of endotherms

AbstractAimTo understand how climatic conditions influence the geographical distributions of species and their potential responses to climate change, we investigated the relationships between the thermal tolerances of species and the size and limits of their distributions. We tested two hypotheses for endotherms: the climatic variability hypothesis, which predicts increases in range size with increasing breadth of thermal tolerance, and the climatic extreme hypothesis, which predicts that range limits are related to thermal tolerance limits. Furthermore, we tested whether these relationships differ between temperate and tropical areas.LocationGlobal.Time periodPresent.Major taxa studiedBirds and mammals.MethodsWe compiled data on thermal tolerances that had been measured in physiological experiments for 453 endothermic species, along with information on geographical ranges and climatic conditions. We applied phylogenetic generalized least square regressions to test for relationships between thermal tolerance and (a) range size or limits and (b) breadth and extremes of the climatic conditions that each species experiences across its distribution.ResultsWe found that range size was not related to the breadth thermal tolerance for endotherms. However, the range limits at high latitudes as well as the minimum temperatures experienced by species were closely related to the physiological cold tolerances of species. These relationships were particularly strong in temperate regions, but these patterns were not found in the tropics.Main conclusionsOur results are inconsistent with the predictions of the climatic variability hypothesis, but are in line with the predictions of the climatic extreme hypothesis. Furthermore, the factors determining species distributions do not appear to be the same in tropical and temperate regions. Our study emphasizes the need to combine spatially explicit distribution models with information from physiological experiments in order to capture regional differences and improve predictions of the responses of species to climate change.

The Limits of Radical Parties in Coalition Foreign Policy: Italy, Hijacking, and the Extremity Hypothesis

Scholars increasingly suggest that coalition governments produce more extreme foreign policies than single-party governments. Extremity is especially likely when governments include radical parties that take extreme positions on foreign policy issues and are “critical” to the government’s survival, as the radical parties push the centrist ones toward the extremes. A look at Italy’s Second Republic provides an important counterpoint to the extremity hypothesis. In three high-profile cases of military operations—Albania 1997, Kosovo 1999, and Afghanistan 2006–08—Italy had a center-left government that depended on radical parties for its survival. In all cases, the radical parties opposed military operations but did not prevent the government from acting by forcing the government’s fall. Our article seeks to explain the limits of leftist radical parties in Italy’s Second Republic. We argue first that radical parties are reluctant to threaten or force government collapse as this can lead to an opposition coalition coming to office and voters’ being blamed for the outcome. Second, we claim that foreign policy has been less important to radical parties than domestic issues. Finally, we argue that radical parties have appealed to their voters through theatrical politics and have affected the implementation of military operations.

Floodplain persistence and dynamic-equilibrium conditions in a canyon environment

Canyon river systems are laterally constrained by steep walls, strath terraces, and bedrock intrusions; however, semialluvial reaches are nested within these environments as discontinuous floodplains along the river margins. These semialluvial floodplains provide an example of dynamic-equilibrium set within high-energy fluvial systems, marking areas where the river is free to alter its boundary conditions. Most research has focused on hydraulic conditions necessary for floodplain formation and persistence in unconfined systems, whereas little is known about canyon streams. This paper focuses on (1) characterizing dynamic-equilibrium, (2) describing the controls on floodplain formation and distribution, and (3) evaluating the performance of extremal hypotheses to identify dynamic-equilibrium and floodplain persistence in high-energy, semiconfined canyon environments.These objectives were addressed with field and numerical data derived from a one-dimensional hydraulic model for bankfull and 100-year return interval flood events, supported by closely spaced cross sections for the lower 38-km canyon reach of the Deadwood River (Idaho). Under bankfull conditions, critical energy thresholds for equilibrium floodplain persistence at this study site present the upper limits of: slope=0.018, shear stress=175N/m2, and specific stream power=400W/m2. Channel and floodplains near equilibrium, quantified with a near-zero sediment transport divergence (Exner equation), were successfully identified by the minimum unit stream power extremal hypothesis and to a lesser degree by the other extremal hypotheses that minimize energy expenditure (minimum specific stream power, minimum total stream power, and minimum Froude number), provided backwater environments and major tributaries could be identified. Extremal results were compared to hydraulic geometry relations to evaluate how closely equilibrium floodplains approached values for unconfined alluvial river systems.

Comparing different energy partitions at scission used in prompt emission model codes GEF and Point-by-Point

Different methods to partition the total excitation energy (TXE) of fully accelerated fragments, presently used in prompt emission calculations include different assumptions about what is happening at scission. In fact the energy partition takes place at scission or even before scission, depending on the physical assumptions supporting the models used in different methods of TXE partition.The paper discusses two TXE partition methods in which the amount of energy to be shared (at scission and before scission, respectively) is very different. These methods (based on different principles and physical considerations) are: A. The method used in the Point-by-Point (PbP) treatment of prompt emission in which the available excitation energy at scission is shared between complementary nascent fragments. The amount of energy to be shared is sufficiently high to consider the nascent fragments in the Fermi-gas regime of the level density. B. The method used in the GEF code, in which the intrinsic energy before scission is shared between pre-nascent fragments according to the “energy sorting mechanism”. This sorting mechanism is based on the assumption of level densities in the constant temperature regime, only. This is supported by the low amount of the shared intrinsic energy in the case of thermal and low energy neutron induced fission.Taking into account that the principles and physical considerations of any TXE partition method are independent on the way to treat the prompt emission (i.e. deterministically as in the PbP model or probabilistically by Monte-Carlo as in the code GEF) the methods A and B are applied to the same fission fragment range (built as in the PbP treatment). Extreme hypotheses are made for the fragment level densities on which the partitions are based (only in the Fermi-gas regime or only in the constant temperature regime). The results are compared with the energy partition obtained with fragment level densities described by the composite Gilbert–Cameron formula. Different assumptions for the deformation energies of fragments (absolute deformation at scission, or extra-deformation at scission with respect to the full acceleration) impacting the sawtooth-like shape of the excitation energy E⁎(A) at full acceleration are discussed, too. Limitations and advantages of these methods are also mentioned. Both TXE partition methods applied in the PbP model lead to prompt emission results (e.g. ν(A) and Eγ(A)) describing well the experimental data.

Regime theories in gravel‐bed rivers: models, controlling variables, and applications in disturbed Italian rivers

AbstractDownstream hydraulic geometry relationships describe the shape of alluvial channels in terms of bankfull width, flow depth, flow velocity, and channel slope. Recent investigations have stressed the difference in spatial scales associated with these variables and thus the time span required for their adjustment after a disturbance. The aim of this study is to explore the consequences in regime models considering the hypothesis that while channel width and depth adjust quickly to changes in water and sediment supply, reach slope requires a longer time span. Three theoretical models were applied. One model incorporates an extremal hypothesis (Millar RG. 2005. Theoretical regime equations for mobile gravel‐bed rivers with stable banks. Geomorphology 64: 207–220), and the other two are fully physically based (Ikeda S, Parker G, Kimura Y. 1988. Stable width and depth of straight gravel rivers with heterogeneous bed materials. Water Resources Research 24: 713–722; Parker G, Wilcock PR, Paola C, Dietrich W, Pitlick J. 2007. Physical basis for quasi universal relations describing bankfull hydraulic geometry of single‐thread gravel‐bed rivers. Journal of Geophysical Research 112, DOI: 10.1029/2006JF000549). In order to evaluate the performance of models introducing the slope as an independent variable, we propose two modifications to previous models.The performance of regime models was tested against published data from 142 river reaches and new hydraulic geometry data from gravel‐bed rivers in Patagonia (Argentina) and north‐eastern Italy.Models that assume slope as a control (Ikeda et al., 1988; or Millar, 2005) predict channel depth and width reasonably well. Parker et al.'s (2007) model improved predictions because it filters the scatter in slope data with a relation slope–discharge. The extremal hypothesis model of Millar (2005) predicts comparably to the other physically based models.Millar's model was chosen to describe the recent changes in the Piave and Brenta rivers due to human intervention – mainly in‐channel gravel mining. The change in sediment supply and recovery was estimated for these rivers. This study supports the interpretation that sediment supply is the key factor guiding morphological changes in these rivers. Copyright © 2013 John Wiley & Sons, Ltd.

Authors are also reviewers: problems in assigning cause for missing negative studies

I compare two possible extreme hypotheses regarding submission of papers to journals: the Q hypothesis, whereby the decision to submit is based on quality of research; and the P hypothesis, whereby it is based on probability of acceptance. I give five reasons as to why the P hypothesis is more plausible and suggest that problems of missing data may previously have caused researchers to misinterpret the evidence on editorial bias.

Authors are also reviewers: problems in assigning cause for missing negative studies

I compare two possible extreme hypotheses regarding submission of papers to journals: the Q hypothesis, whereby the decision to submit is based on quality of research; and the P hypothesis, whereby it is based on probability of acceptance. I give five reasons as to why the P hypothesis is more plausible and suggest that problems of missing data may previously have caused researchers to misinterpret the evidence on editorial bias.

On the spin and parity of a single-produced resonance at the LHC

Both LHC experiments, ATLAS and CMS, observed a new narrow resonance near 125 GeV.We demonstrate that the spin, parity, and, more generally, the tensor structure of the boson couplings of this resonance can be obtained by studying mass and angular distributions of events where the resonance decays to pairs of gauge bosons, ZZ, WW and γγ To account for all spin correlations we calculate kinematic distributions analytically and develop a Monte Carlo generator. We also discuss how to use angular and mass distributions of the resonance decay products for optimal background rejection and for distinguishing different signal hypotheses. By the end of the 8 TeV run of the LHC, it might be possible to separate extreme hypotheses of the spin and parity of the new resonance with a confidence level of 99% or better for a wide range of models.

Spin and parity of a single-produced resonance at the LHC

The experimental determination of the properties of the newly discovered boson at the Large Hadron Collider is currently the most crucial task in high-energy physics. We show how information about the spin, parity, and, more generally, the tensor structure of the boson couplings can be obtained by studying angular and mass distributions of events in which the resonance decays to pairs of gauge bosons, $ZZ$, $WW$, and $\ensuremath{\gamma}\ensuremath{\gamma}$. A complete Monte Carlo simulation of the process $pp\ensuremath{\rightarrow}X\ensuremath{\rightarrow}VV\ensuremath{\rightarrow}4f$ is performed and verified by comparing it to an analytic calculation of the decay amplitudes $X\ensuremath{\rightarrow}VV\ensuremath{\rightarrow}4f$. Our studies account for all spin correlations and include general couplings of a spin $J=0$, 1, 2 resonance to Standard Model particles. We also discuss how to use angular and mass distributions of the resonance decay products for optimal background rejection. It is shown that by the end of the 8 TeV run of the LHC, it might be possible to separate extreme hypotheses of the spin and parity of the new boson with a confidence level of 99% or better for a wide range of models. We briefly discuss the feasibility of testing scenarios where the resonance is not a parity eigenstate.

Evaluating Qualitative Methods with Emphasis on Global Studies

Knowledge building has been the evaluative standard for qualitative methods for decades. This paper analyzes how qualitative techniques succeed in knowledge building. Social action research explains that effective social analysis sometimes require involvement. Critical action research demands research accomplish a positive purpose. The historical influence of early qualitative methods evidences a social commitment. The process of knowledge building now attempted by qualitative methods is influenced by social concern. The process of knowledge building is explained to follow social realities that are both analyzable and unanalyzable. Some societies welcome social science whereas others are almost completely closed. Social science seeks knowledge about both types of cultures. Knowledge may be acquired in a haphazard way or knowledge may be sought systematically. From the interest in creating emergent knowledge, various qualitative methods techniques have developed. Qualitative methods still maintains the traditional social science connection to data. Qualitative methods findings must emanate from data. How data is defined, however, has considerable latitude. The 477 episodes of Verbotene Liebe's Christian and Oliver's Story that uploaded to YouTube are qualitative data. VL is German public television. To exemplify the methodological problems of many types of qualitative data, this paper considers narrative analysis. Narrative analysis allows a discussion of whether qualitative methods can possibly resolve extreme hypotheses. A hypotheses that has profound societal level implications is termed an extreme hypothesis. The C and O's data is analyzed to answer questions about European Union's future. Attempting social science observations about European Union's future from C and O’s data is testing an extreme hypothesis with qualitative data. Hermeneutics technique is used to analyze the C and O's data. A purposive sample of three episodes is selected. Developments in each case in the sample is sequentially analyzed. Character's narrative identity, audience's urban myth identity, and Eric Erickson's concept of generativity are followed, sequentially. Such data analysis allows interpretivist conclusions. The paper's purpose is to analyze the usefulness of qualitative methods in global studies. Following narrative data substantiates that qualitative methods could be invaluable in global studies. Beyond that, the themes followed in C and O's indicate a high level of belief in German culture. The issue of limits for the adaptation to Europe Union are popularly presented. Disparity of wealth among union members is a concern. German establishment virtues are shown capable of producing public goods. Social issue liberalism is offered as evidence that Germany is succeeding acquiring long sought accoutrements of democracy. The German audience is encouraged to maintain options other than European Union.

Inconsistency-based active learning for support vector machines

In classification tasks, active learning is often used to select out a set of informative examples from a big unlabeled dataset. The objective is to learn a classification pattern that can accurately predict labels of new examples by using the selection result which is expected to contain as few examples as possible. The selection of informative examples also reduces the manual effort for labeling, data complexity, and data redundancy, thus improves learning efficiency. In this paper, a new active learning strategy with pool-based settings, called inconsistency-based active learning, is proposed. This strategy is built up under the guidance of two classical works: (1) the learning philosophy of query-by-committee (QBC) algorithm; and (2) the structure of the traditional concept learning model: from-general-to-specific (GS) ordering. By constructing two extreme hypotheses of the current version space, the strategy evaluates unlabeled examples by a new sample selection criterion as inconsistency value, and the whole learning process could be implemented without any additional knowledge. Besides, since active learning is favorably applied to support vector machine (SVM) and its related applications, the strategy is further restricted to a specific algorithm called inconsistency-based active learning for SVM (I-ALSVM). By building up a GS structure, the sample selection process in our strategy is formed by searching through the initial version space. We compare the proposed I-ALSVM with several other pool-based methods for SVM on selected datasets. The experimental result shows that, in terms of generalization capability, our model exhibits good feasibility and competitiveness.

Religious Commitment and Social Integration: Are there Significant Links? A Pilot Study of Muslims in the Oslo Area with a Family Background from Pakistan

Conducted in 2010, the study examines possible connections between religious commitment and social integration in Norwegian society among first and 'second generation' Muslim immigrants living in the Oslo area, with a family background from Pakistan. The pilot study is based on qualitative interviews with nineteen informants, selected from different social groups, and irrespectively of their association with religious organizations. They are distributed among different age groups (from 21 to 68 years), class backgrounds and gender (10 women and 9 men). In the interviews with informants, answers were sought to three questions: How do informants themselves understand the relationship between their religious commitment and their participation in or sense of belonging to (i.e. their 'social integration' into) Norwegian society? In what contexts and situations do informants experience that there is a direct correlation between being Muslim and being more or less included in, or excluded from, Norwegian society? What roles do religious norms and ideals play in strengthening or weakening the motivation of informants for involvement, participating in, and contributing to arenas of society other than the religious? Neither of two extreme hypotheses: (i) A high degree of religious commitment tends to weaken social integration; and (ii) A high degree of religious commitment tends to strengthen social integration; were confirmed beyond reasonable doubt. Judging from the research material, however, the latter hypothesis (ii) appeared to receive significantly higher support than did the first hypothesis (i). Specific relationships between the variables 'religion' and 'integration' are exemplified in the material. But more wide-ranging empirical research and more thorough systematic analyses than provided by this pilot study are called for.

Parameter tracking with partial forgetting method

SUMMARYThis paper concerns the Bayesian tracking of slowly varying parameters of a linear stochastic regression model. The modelled and predicted system output is assumed to possess time‐varying mean value, whereas its dynamics are relatively stable. The proposed estimation method models the system output mean value by time‐varying offset. It formulates three extreme hypotheses on model parameters' variability: (i) no parameter varies; (ii) all parameters vary; and (iii) the offset varies. The Bayesian paradigm then provides a mixture as posterior distribution, which is appropriately projected to a feasible class. Exponential forgetting at ‘second’ hypotheses level allows tracking of slow variations of respective hypotheses.The developed technique is an example of a general procedure called partial forgetting. Focus on a simple example allows to demonstrate essence of the approach. Moreover, it is important per se as it corresponds with a varying load of otherwise (almost) time‐invariant dynamic system. Copyright © 2011 John Wiley & Sons, Ltd.

Early (Day −7) versus Conventional (Day −1) Inception of Cyclosporine-A for Graft-versus-Host Disease Prophylaxis after Unrelated Donor Hematopoietic Stem Cell Transplantation in Children. Long-Term Results of an AIEOP Prospective, Randomized Study

We carried out a randomized, multicenter study comparing the inception of cyclosporine- A (CsA) on day -7 to conventional CsA (on day -1) to evaluate the influence of this modification on graft-versus-host disease (GVHD), treatment-related mortality (TRM), relapse rate (RR), and event-free survival (EFS) in children with hematologic malignancies given unrelated donor (UD) hematopoietic stem cell transplantation (HSCT). Between 1997 and 2002, 152 children transplanted for acute leukemia (102), myelodysplastic syndromes (23), chronic myelogenous leukemia (20), and non-Hodgkin lymphoma (7) were enrolled in the study and randomized to receive either early CsA (group 1, N = 72) or conventional CsA (group 2, N = 80), after stratification according to HLA compatibility and disease phase. The cumulative incidence of both grade II-IV and grade II-IV acute GVHD (aGVHD), as well as of chronic GVHD (cGVHD), did not differ between the 2 groups. No significant differences were observed also with regard to TRM and RR. The 8-year Kaplan-Meier estimates of EFS were 56% in group 1, and 46% in group 2 (P = NS). In the Cox model, advanced disease phase, male recipient, older donor, and occurrence of grade III-IV aGVHD predicted inferior overall EFS. These data indicate that early inception of CsA does not improve posttransplantation outcome of children with hematologic malignancies given UD-HSCT.

Consumption and Children

Consumption by couples rises sharply in the beginning and falls later in life; the causes of the early rise are hotly contested. Among the suggestions are rule of thumb behavior, demographics, liquidity constraints, the precautionary motive, and nonseparabilities between consumption and labor supply. We develop two tests of the extreme hypothesis that only changes in family structure matter. We estimate effects of the numbers and ages of children on consumption. These estimates allow us to rationalize all of the increase in consumption without recourse to any of the causal mechanisms. Our estimates can be interpreted either as giving upper bounds on the effects of children or as evidence that the other causes are not important.

Extremal Expectations: A Paradigm for Fat-Tails

The 'rational expectations hypothesis (REH)' assumes that investors' subjective probability measures coincide with their objective probability measures and all new and relevant information is instantaneously absorbed into these objective distribution measure or prices. A related idea is the efficient market hypothesis which states that the prices of securities as observed reflect all publicly available information. The observed randomness of asset returns re-affirms this line of argument. However, the empirical nonnormality (or fat-tails) of the return distributions continues to be an unexplained anomaly. This paper is based on the rational expectations hypothesis but allows the objective probability measures to be modified to form subjective expectations. Investors remain rational but they revise their original expectations prior to trading based on their buy-sell decisions i.e. they attempt to maximize their expected utilities by adopting decision-biased extreme-valued posterior subjective probabilities based on their prior objective probability measures. A hypothesis called the 'extremal expectations hypothesis (EEH)' is proposed using extreme-valued theory concepts to support the empirical findings.

In Vivo Targeting of the Yeast Pop2 Deadenylase Subunit to Reporter Transcripts Induces Their Rapid Degradation and Generates New Decay Intermediates

Deadenylation is the rate-limiting step of mRNA decay, yet little is known about the mechanism regulating this process. In yeast, deadenylation is mainly mediated by the Pop2-Ccr4 complex. We tested whether the selective recruitment of this deadenylase to target mRNAs was sufficient to stimulate their decay in vivo. For this purpose, the Pop2 factor was fused to a U1A RNA binding domain while U1A binding sites were inserted in untranslated regions of a reporter transcript. Analysis of the reporter fate in strains expressing the Pop2-U1A-RBD fusion demonstrated a specific activation of target mRNA decay. Increased mRNA degradation involved accumulation of deadenylated mRNAs that was not detected when the control factors Dcp2 or Pub1 were tethered to the same transcript. The rapid target mRNA degradation was also accompanied by the appearance of new decay intermediates generated by the 3' -5' trimming of the corresponding 3' -untranslated region. Interestingly, this process was not mediated by the exosome but may result from the activity of the Pop2-Ccr4 deadenylase itself. These results indicate that selective recruitment of the Pop2-Ccr4 deadenylase is sufficient to activate mRNA decay, even though this process can also be stimulated by additional mechanisms. Furthermore, deadenylase recruitment affects the downstream path of mRNA decay.

A conceptual model for meander initiation in bedload‐dominated streams

AbstractA simple analytic model is presented relating local sediment transport capacity to variance in the transverse shear stress distribution in a stream channel. The model is used to develop a physically based conceptual model for the initiation of meandering in straight, bedload‐dominated streams as a result of a feedback mechanism. The feedback maximizes the cross‐sectional shear stress variance and – in order to achieve stability – ultimately minimizes the energy slope at repeated locations along the channel, subject to steady‐state mass flux and the stability of the channel boundary. These locations develop into pools in a fully developed meandering channel; they represent attractor states wherein sediment continuity is satisfied using the least possible energy expenditure per unit length of channel. However, since the cross‐sectional geometry of a pool (and the adjacent bar) is asymmetric, these attractor states are only conditionally stable, requiring strong, curvature‐induced secondary circulation to maintain their asymmetry. Between two successive pools, a stream occupies a metastable, higher energy state (corresponding to a riffle) that requires greater energy expenditure per unit length of channel to transport the same volume of sediment. The model we present links processes at the scale of a channel width to adjustments of the channel sinuosity and slope at the scale of a channel reach. We argue that the reach‐scale extremal hypotheses employed by rational regime models are mathematical formalisms that permit a one‐dimensional theory to describe the three‐dimensional dynamics producing stream morphology. Our model is consistent with the results from stream table experiments, with respect to both the rate of development of meandering and the characteristics of the equilibrium channel morphology. Copyright © 2006 John Wiley & Sons, Ltd.

Predictors of Crohn’s Disease

Early intensive therapy in Crohn's disease should be considered only in patients with disabling disease. The aim of our study was to identify at diagnosis factors predictive of a subsequent 5-year disabling course. Among the 1526 patients seen at our unit with Crohn's disease diagnosed between 1985 and 1998, we excluded patients operated on within the first month of the disease, patients with inadequate data, and patients with severe chronic nondigestive disease. In the 1188 remaining patients, Crohn's disease course within the first 5 years of the disease was categorized as disabling when at least 1 of the criteria of clinical severity, conventionally predefined, was present. Among the 1123 patients with follow-up data allowing full 5-year course classification, the rate of disabling disease was 85.2%. Independent factors present at diagnosis and significantly associated with subsequent 5-year disabling were the initial requirement for steroid use (OR 3.1 [95% CI: 2.2-4.4]), an age below 40 years (OR 2.1 [95% CI: 1.3-3.6]), and the presence of perianal disease (OR 1.8 [95% CI: 1.2-2.8]). The positive predictive value of disabling disease in patients with 2 and 3 predictive factors of disabling disease was 0.91 and 0.93, respectively. These values were 0.84 and 0.91, respectively, when tested prospectively in an independent group of 302 consecutive patients seen at our institution from 1998. At diagnosis of Crohn's disease in a referral center, factors predictive of subsequent 5-year disabling course are an age below 40 years, the presence of perianal disease, and the initial requirement for steroids.