bluuebunny/crossref_metadata_2025 huggingface dataset:
The environment, security and regional cooperation in Central Asia
Authors: Tookey Douglas L.
Published: May 2007

Environmental challenges, resulting from either a scarcity of natural resources or environmental degradation, may contribute to security risks in Central Asia. An encouraging sign is the recent attention of the governments of Central Asia, civil society groups and international organizations to these environmental security issues. Their efforts indicate that by working together to prevent conflicts caused by environmental problems, cooperation among the countries of Central Asia may expand. Both short and long-term obstacles must be overcome if these groups are to ensure that environmental stresses do not lead to security concerns.
Marginal zinc deficiency in rats decreases leptin expression independently of food intake and corticotrophin-releasing hormone in relation to food intake
Authors: Kwun In-Sook , Cho Young-Eun , Lomeda Ria-Ann R. , Kwon Soon-Tae , Kim Yangha , Beattie John H.
Published: May 2007

Zn deficiency reduces food intake and growth rate in rodents. To determine the relationship between Zn deficiency and the regulation of food intake, we evaluated leptin gene expression in epididymal white adipose tissue (eWAT), and hypothalamic corticotropin-releasing hormone (hCRH) and hypothalamic neuropeptide Y (hNPY) of rats Zn-deficient only to show reduced food intake and growth rate but not food intake cycling. Growing male Sprague-Dawley rats (240 g) were randomly assigned to one of four dietary groups: Zn-adequate (ZA; 30 mg/kg diet), Zn-deficient (ZD; 3 mg/kg diet), pair-fed with ZD (PF; 30 mg/kg diet) and Zn-sufficient (ZS; 50 mg/kg diet) (n 8), and were fed for 3 weeks. Food intake and body weight were measured, as were blood mononuclear cells and pancreas Zn levels. eWAT leptin, hCRH and hNPY mRNA levels were determined. Food intake was decreased by about 10 % in ZD and PF rats compared to ZA and ZS rats. Growth and eWAT leptin mRNA levels were unaffected in PF rats but were significantly (P < 0·05) decreased in ZD rats. However, hNPY showed a tendency to increase, and hCRH significantly (P < 0·05) decreased, in both ZD and PF rats. These results suggest that while leptin gene expression may be directly affected by Zn, hNPY and hCRH are likely responding to reduced food intake caused by Zn deficiency.
‘A Picturesque but Hopeless Resistance’: Rehe in 1933
Authors: PHILLIPS RICHARD T.
Published: May 2007

The Japanese invasion of Rehe in 1933 proved to be a walkover, despite the intense rhetoric of resistance which had characterised statements by leaders in north China in early 1933. This article looks at the local context of the governorship of Tang Yulin, at the role of Zhang Xueliang and regional leaders, and at the central government's involvement, principally through Song Ziwen (T.V. Soong), in order to understand China's failure in Rehe. This failure strongly influenced the subsequent Tanggu truce and affected the careers of Song and Zhang in the short term, but did not deter Jiang Jieshi from continuing his anti-communist encirclement campaigns.
‘We are all sondukarar (relatives)!’: kinship and its morality in an urban industry of Tamilnadu, South India
Authors: DE NEVE GEERT
Published: May 2007

This article is concerned with the role of kinship and kin morality in contexts of work in South Asia. It focuses on the highly ambivalent nature of kin morality when mobilised outside the household and the family. Ethnographic evidence from a small-scale industry in Tamilnadu, South India, shows how employers frequently invoke the morality of kinship and caste in an attempt to secure a reliable and compliant labour force and to avoid overt class confrontation. However, employers’ efforts to promote kinship—real or fictive—and its morality in the workplace appear inadequate in the face of high labour turnover and frequently collapsing employer-worker relationships in small-scale industries. While employers’ repeated use of kin ideology succeeds in silencing the workers on the shop floor, it is much less effective in securing a stable labour force in the long run. The argument put forward here points to the limits of kin morality and questions its effectiveness in informal contexts of labour employment. The discussion sheds new light on the role of caste and kinship in recruiting, retaining and disciplining labour in India's informal economy.
A framework for the unification of the behavioral sciences
Authors: Gintis Herbert
Published: May 2007

The various behavioral disciplines model human behavior in distinct and incompatible ways. Yet, recent theoretical and empirical developments have created the conditions for rendering coherent the areas of overlap of the various behavioral disciplines. The analytical tools deployed in this task incorporate core principles from several behavioral disciplines. The proposed framework recognizes evolutionary theory, covering both genetic and cultural evolution, as the integrating principle of behavioral science. Moreover, if decision theory and game theory are broadened to encompass other-regarding preferences, they become capable of modeling all aspects of decision making, including those normally considered “psychological,” “sociological,” or “anthropological.” The mind as a decision-making organ then becomes the organizing principle of psychology.
Towards uniting the behavioral sciences with a gene-centered approach to altruism
Authors: Brown R. Michael , Brown Stephanie L.
Published: May 2007

We support the ambitious goal of unification within the behavioral sciences. We suggest that Darwinian evolution by means of natural selection can provide the integrative glue for this purpose, and we review our own work on selective investment theory (SIT), which is an example of how other-regarding preferences can be accommodated by a gene-centered account of evolution.
Evolutionary theory and the social sciences
Authors: Burgess Robert L. , Molenaar Peter C. M.
Published: May 2007

Gintis's article is an example of growing awareness by social scientists of the significance of evolutionary theory for understanding human nature. Although we share its main point of view, we comment on some disagreements related to levels of behavioral analysis, the explanation of social cooperation, and the ubiquity of inter-individual differences in human decision-making.
The limitations of unification
Authors: Markman Arthur B.
Published: May 2007

There are two roadblocks to using game theory as a unified theory of the behavioral sciences. First, there may not be a single explanatory framework suitable for explaining psychological processing. Second, even if there is such a framework, game theory is too limited, because it focuses selectively on decision making to the exclusion of other crucial cognitive processes.
More obstacles on the road to unification
Authors: Smith Eric Alden
Published: May 2007

The synthesis proposed by Gintis is valuable but insufficient. Greater consideration must be given to epistemological diversity within the behavioral sciences, to incorporating historical contingency and institutional constraints on decision-making, and to vigorously testing deductive models of human behavior in real-world contexts.
Unifying the behavioral sciences II
Authors: Gintis Herbert
Published: May 2007

My response to commentators includes a suggestion that an additional principle be added to the list presented in the target article: the notion of human society as a complex adaptive system with emergent properties. In addition, I clear up several misunderstandings shared by several commentators, and explore some themes concerning future directions in the unification of the behavioral science.
Consciousness without a cerebral cortex: A challenge for neuroscience and medicine
Authors: Merker Bjorn
Published: May 2007

A broad range of evidence regarding the functional organization of the vertebrate brain – spanning from comparative neurology to experimental psychology and neurophysiology to clinical data – is reviewed for its bearing on conceptions of the neural organization of consciousness. A novel principle relating target selection, action selection, and motivation to one another, as a means to optimize integration for action in real time, is introduced. With its help, the principal macrosystems of the vertebrate brain can be seen to form a centralized functional design in which an upper brain stem system organized for conscious function performs a penultimate step in action control. This upper brain stem system retained a key role throughout the evolutionary process by which an expanding forebrain – culminating in the cerebral cortex of mammals – came to serve as a medium for the elaboration of conscious contents. This highly conserved upper brainstem system, which extends from the roof of the midbrain to the basal diencephalon, integrates the massively parallel and distributed information capacity of the cerebral hemispheres into the limited-capacity, sequential mode of operation required for coherent behavior. It maintains special connective relations with cortical territories implicated in attentional and conscious functions, but is not rendered nonfunctional in the absence of cortical input. This helps explain the purposive, goal-directed behavior exhibited by mammals after experimental decortication, as well as the evidence that children born without a cortex are conscious. Taken together these circumstances suggest that brainstem mechanisms are integral to the constitution of the conscious state, and that an adequate account of neural mechanisms of conscious function cannot be confined to the thalamocortical complex alone.
The mesencephalon as a source of preattentive consciousness
Authors: Aboitiz Francisco , López-Calderón Javier , López Vladimir
Published: May 2007

By themselves, mesencephalic subcortical mechanisms provide a preattentive kind of consciousness, related to stimulus-related, short-latency dopamine release triggered by collicular input. Elaborate forms of consciousness, containing identifiable objects (visual, auditory, tactile, or chemical), imply longer-lasting phenomena that depend on the activation of prosencephalic networks. Nevertheless, the maintenance of these higher-level networks strongly depends on long-lasting mesencephalic dopamine release.
Consciousness, cortical function, and pain perception in nonverbal humans
Authors: Anand K. J. S.
Published: May 2007

Postulating the subcortical organization of human consciousness provides a critical link for the construal of pain in patients with impaired cortical function or cortical immaturity during early development. Practical implications of the centrencephalic proposal include the redefinition of pain, improved pain assessment in nonverbal humans, and benefits of adequate analgesia/anesthesia for these patients, which certainly justify the rigorous scientific efforts required.
Subcortical consciousness: Implications for fetal anesthesia and analgesia
Authors: Brusseau Roland R. , Mashour George A.
Published: May 2007

In this commentary we discuss the possibility of subcortical consciousness and its implications for fetal anesthesia and analgesia. We review the neural development of structural and functional elements that may participate in conscious representation, with a particular focus on the experience of pain.
Corticothalamic necessity, qualia, and consciousness
Authors: Doesburg Sam M. , Ward Lawrence M.
Published: May 2007

The centrencephalic theory of consciousness cannot yet account for some evidence from both brain damaged and normally functioning humans that strongly implicates thalamocortical activity as essential for consciousness. Moreover, the behavioral indexes used by Merker to implicate consciousness need more development, as, besides being somewhat vague, they lead to some apparent contradictions in the attribution of consciousness.
Roles of allocortex and centrencephalon in intentionality and consciousness
Authors: Freeman Walter J.
Published: May 2007

“Decortication” does not distinguish between removing all cerebral cortex, including three-layered allocortex or just six-layered neocortex. Functional decortication, by spreading depression, reversibly suppresses only neocortex, leaving minimal intentionality. Removal of all forebrain structures except a hypothalamic “island” blocks all intentional behaviors, leaving only tropisms. To what extent do Merker's examples retain allocortex, and how might such residues affect his interpretations?
I Promethean, bound deeply and fluidly among the brain's associative robotic networks
Authors: Glassman Robert B.
Published: May 2007

Merker's insightful broad review fertilely recasts the mind/brain issue, but the phenomenological appeals require additional considerations of behavioral and neural flexibility. Motor equivalences and perceptual constancies may be cortical contributions to a “robotic” tectal orientation mechanism. Intermediate “third layers” of associative neural networks, each with a few diffusely summing convergence-divergence modules, may be the economical expedient by which evolution has extended the limited unity-in-diversity of sensorimotor coordination to perception, action, thinking, and memory.
Levels of emotion and levels of consciousness
Authors: Izard Carroll
Published: May 2007

Merker makes a strong case for the upper brain stem as being the neural home of primary or phenomenal consciousness. Though less emphasized, he makes an equally strong and empirically supported argument for the critical role of the mesodiencephalon in basic emotion processes. His evidence and argument on the functions of brainstem systems in primary consciousness and basic emotion processes present a strong challenge to prevailing assumptions about the primacy of cognition in emotion-cognition-behavior relations.
Supracortical consciousness: Insights from temporal dynamics, processing-content, and olfaction
Authors: Morsella Ezequiel , Bargh John A.
Published: May 2007

To further illuminate the nature of conscious states, it may be progressive to integrate Merker's important contribution with what is known regarding (a) the temporal relation between conscious states and activation of the mesodiencephalic system; (b) the nature of the information (e.g., perceptual vs. premotor) involved in conscious integration; and (c) the neural correlates of olfactory consciousness.
Who dominates who in the dark basements of the brain?
Authors: Prescott Tony J. , Humphries Mark D.
Published: May 2007

Subcortical substrates for behavioural integration include the fore/midbrain nuclei of the basal ganglia and the hindbrain medial reticular formation. The midbrain superior colliculus requires basal ganglia disinhibition in order to generate orienting movements. The colliculus should therefore be seen as one of many competitors vying for control of the body's effector systems with the basal ganglia acting as the key arbiter.
The functional utility of consciousness depends on content as well as on state
Authors: Seth Anil K.
Published: May 2007

This commentary considers Merker's mesodiencephalic proposal in relation to quantitative measures of neural dynamics suggested to be relevant to consciousness. I suggest that even if critical neural mechanisms turn out to be subcortical, the functional utility of consciousness will depend on the rich conscious contents generated by continuous interaction of such mechanisms with a thalamocortical envelope.
The human superior colliculus: Neither necessary, nor sufficient for consciousness?
Authors: Watkins Susanne , Rees Geraint
Published: May 2007

Non-invasive neuroimaging in humans permits direct investigation of the potential role for mesodiencephalic structures in consciousness. Activity in the superior colliculus can be correlated with the contents of consciousness, but it can be also identified for stimuli of which the subject is unaware; and consciousness of some types of visual stimuli may not require the superior colliculus.
Affirmative-action for the brainstem in the neuroscience of consciousness: The zeitgeist of the brainstem as a “dumb arousal” system
Authors: Watt Douglas F.
Published: May 2007

Merker offers a remarkable statement about the neural integration essential to conscious states provided by the mesodiencephalon. The model for triangular interaction between action selection, target selection, and emotion is heuristic. Unfortunately, there is little interest (relatively speaking) in neuroscience in the mesodiencephalon, and attention is currently heavily directed to the telencephalon. This suggests that there may be less real momentum than commonly assumed towards the Holy Grail of neuroscience, a scientific theory of mind, despite the major upsurge in interest.
Modelling respiratory infection control measure effects
Authors: LIAO C. M. , CHEN S. C. , CHANG C. F.
Published: May 2007

One of the most pressing issues in facing emerging and re-emerging respiratory infections is how to bring them under control with current public health measures. Approaches such as the Wells–Riley equation, competing-risks model, and Von Foerster equation are used to prioritize control-measure efforts. Here we formulate how to integrate those three different types of functional relationship to construct easy-to-use and easy-to-interpret critical-control lines that help determine optimally the intervention strategies for containing airborne infections. We show that a combination of assigned effective public health interventions and enhanced engineering control measures would have a high probability for containing airborne infection. We suggest that integrated analysis to enhance modelling the impact of potential control measures against airborne infections presents an opportunity to assess risks and benefits. We demonstrate the approach with examples of optimal control measures to prioritize respiratory infections of severe acute respiratory syndrome (SARS), influenza, measles, and chickenpox.
Blow-up similarity solutions of the fourth-order unstable thin film equation
Authors: EVANS J. D. , GALAKTIONOV V. A. , KING J. R.
Published: May 2007

We study blow-up behaviour of solutions of the fourth-order thin film equationwhich contains a backward (unstable) diffusion term. Our main goal is a detailed study of the case of the first critical exponentwhereN≥ 1 is the space dimension. We show that the free-boundary problem with zero contact angle and zero-flux conditions admits continuous sets (branches) of blow-up self-similar solutions. For the Cauchy problem inRN×R+, we detect compactly supported blow-up patterns, which have infinitely many oscillations near interfaces and exhibit a “maximal” regularity there. As a key principle, we use the fact that, for small positiven, such solutions are close to the similarity solutions of the semilinear unstable limit Cahn-Hilliard equationwhich are better understood and have been studied earlier [19]. We also discuss some general aspects of formation of self-similar blow-up singularities for other values ofp.
On steady states of van der Waals force driven thin film equations
Authors: JIANG HUIQIANG , NI WEI-MING
Published: May 2007

Let$\Omega\subset\mathbb{R}^{N}$,N≥2 be a bounded smooth domain and α > 1. We are interested in the singular elliptic equationwith Neumann boundary conditions. In this paper, a complete description of all continuous radially symmetric solutions is given. In particular, we construct nontrivial smooth solutions as well as rupture solutions. Here a continuous solution is said to be a rupture solution if its zero set is nonempty. WhenN= 2 and α = 3, the equation is used to model steady states of van der Waals force driven thin films of viscous fluids. We also consider the physical problem when total volume of the fluid is prescribed.
The discrete versus continuous controversy in physics
Authors: LESNE ANNICK
Published: May 2007

This paper presents a sample of the deep and multiple interplay between discrete and continuous behaviours and the corresponding modellings in physics. The aim of this overview is to show that discrete and continuous features coexist in any natural phenomenon, depending on the scales of observation. Accordingly, different models, either discrete or continuous in time, space, phase space or conjugate space can be considered. Some caveats about their limits of validity and their interrelationships (discretisation and continuous limits) are pointed out. Difficulties and gaps arising from the singular nature of continuous limits and from the information loss accompanying discretisation are discussed.
Discrete–continuous and classical–quantum
Authors: PAUL THIERRY
Published: May 2007

We present a discussion concerning the opposition between discreteness and the continuum in quantum mechanics. In particular, it is shown that this duality was not restricted to the early days of the theory, but remains current, and features different aspects of discretisation. In particular, the discreteness of quantum mechanics is key for quantum information and quantum computation. We propose a conclusion involving a concept of completeness linking discreteness and the continuum.
Discrete-time and continuous-time modelling: some bridges and gaps
Authors: KRIVINE HUBERT , LESNE ANNICK , TREINER JACQUES
Published: May 2007

The relationship between continuous-time dynamics and the corresponding discrete schemes, and its generally limited validity, is an important and widely acknowledged field within numerical analysis. In this paper, we propose another, more physical, viewpoint on this topic in order to understand the possible failure of discretisation procedures and the way to fix it. Three basic examples, the logistic equation, the Lotka–Volterra predator–prey model and Newton's law for planetary motion, are worked out. They illustrate the deep difference between continuous-time evolutions and discrete-time mappings, hence shedding some light on the more general duality between continuous descriptions of natural phenomena and discrete numerical computations.
236 years ago. . .
Authors: Valsecchi Giovanni B.
Published: May 2007

Some of the problems related to Near Earth Objects (NEOs), like orbit determination and ephemeris computation, are not new, and had to be dealt with since the beginning of NEO astronomy. The latter practically started with the discovery of Comet D/1770 L1 Lexell, that passed very close to the Earth in 1770; studies of the chaotic dynamics of this exceptional object continued well into the XIXth century. At the end of the XXth century there has been a renewal of interest in NEOs, as attested by IAU Symposium 236.
Orbital evolution of short-period comets with high values of the Tisserand constant
Authors: Emel'yanenko N.Yu.
Published: May 2007

The orbital evolution of comets with high values of the Tisserand constant is studied for a time interval of 800 years. Scenarios of dynamical evolution are obtained for 85 comets. Particular features of the orbital evolution of the comets of this class are singled out. The orbits of all comets are tangent to the orbit of Jupiter and have a steadily low inclination. For 80% of comets, the evolution scenario includes a timespan in which the comets move in low-eccentricity orbits. The possibility is analyzed of a change in the Tisserand constant and of a transition of the comet to be controlled by other giant planets.
Some aspects of the statistics of Near-Earth Objects
Authors: Donnison J.R.
Published: May 2007

The distribution of Near-Earth Objects, in particular Near-Earth asteroids is examined using maximum likelihood methods. These are analysed with respect magnitudes, taxonomic classes and to their orbital distances. Comparisons are made with the distributions of main-belt asteroids and short-period comets.
(Mostly) dormant comets in the NEO population and the meteoroid streams that they crumble into
Authors: Jenniskens Peter
Published: May 2007

Many of our annual showers do not have active parent comets. In recent years, minor planets have been identified that move among the meteoroids streams. Some streams, such as the Quadrantids, Geminids, and Sextantids, are in such unusual orbits that the probability of a chance association is only of order 1 in 106. The streams identify those objects as dormant comet nuclei. Other streams, such as the Phoenicids and α-Capricornids are associated with minor planets that were found to be weakly active at their last perihelion passage. All the streams investigated so far are young, less than 2,000 years old, and can not have been created in the classical sense of meteoroids being ejected from the comet nucleus by water vapor drag. Instead, these (mostly) dormant comets lost fragments at some point in the past, which crumbled into meteoroid streams. Scars of such events are now identified on the surface of active Jupiter family comets 9P/Tempel 1 and 81P/Wild 2. Thus, the meteor showers on Earth bear witness to what is the dominant mass-loss mechanism of comets in the inner solar system, a process that can account for much of the zodiacal cloud dust and the zodiacal dust bands.
Properties of meteoroids from different classes of parent bodies
Authors: Borovička Jiří
Published: May 2007

Meteoroids observed to disintegrate in the terrestrial atmosphere can be directly linked to their parent bodies in case that they belong to certain meteor showers. We present a list of two dozens of parent bodies reliably associated with well recognized meteor showers. Among the parent bodies are long period comets, Halley-type comets, Jupiter family comets, comets of the inner solar system (such as 2P/Encke) and asteroids. Physical and chemical properties of meteoroids coming from various parents are compared on the basis of meteor heights, decelerations, light curves and spectra. Jupiter family comets produce meteoroids with the lowest strength, namely porous aggregates of dust grains with bulk densities of about 0.3 g cm−3or less. Halley type material is somewhat stronger and the material related to comet Encke is even stronger. In addition, small strong constituents, perhaps similar to carbonaceous chondrites, can be encountered within the normal cometary material. The strength of cometary material is also enhanced by long-term exposure to cosmic rays and by solar heating in the vicinity to the Sun (r<0.2 AU). Both these processes lead to the loss of volatile sodium. Southern δ-Aquariids, Geminids and partly also Quadrantids were influenced by solar radiation. We argue that these showers, the asteroids associated with them ((3200) Phaethon and 2003 EH1), and the whole interplanetary complexes they belong to are of cometary origin. The argument is supported by lower than chondritic Fe/Mg ratio found in Geminids as well as in Halley type comets. The typical property of stony meteoroids of asteroidal origin is the presence of internal cracks which cause that the incoming meteoroids are much weaker than the recovered meteorites.
Automation of the Czech part of the European fireball network: equipment, methods and first results
Authors: Spurný Pavel , Borovička Jiří , Shrbený Lukáš
Published: May 2007

In the last several years the manually operated fish-eye cameras in the Czech part of the European fireball Network (EN) have been gradually replaced with new generation cameras, the modern and sophisticated completely autonomous fireball observatories (AFO), which were recently developed in the Czech Republic. The main motivation for construction of this new observing system was to continue in regular fireball observations and to make these observations more complex and efficient. In this paper we briefly describe basic design and work of this new instrument and its deployment at the Czech stations of the EN. The current dislocation of the individual stations and their equipment is also discussed. Along with this new modern instrument we developed also new software for measurement of photographic negatives which makes this time consuming work more efficient and easier. The AFOs provide us with data on fireballs far richer and more interesting than those we were able to get in the past. This is illustrated by the cases of two recently observed fireballs which were recorded by the AFOs. We describe the high precision of all the measureded values as well as the very detailed information about light curves in both cases.
Ondřejov's double-station observation of faint meteors using a TV technique (image intensifiers Dedal): 1998–2005
Authors: Štork Rostislav
Published: May 2007

TV cameras equipped with image intensifiers are suitable and often used instruments for observing faint meteors. Our regular double-station observations with image intensifiers Dedal (type Dedal 41) started in 1998. Since 2006 we perform observations using new Mullard XX1332 intensifiers. In this paper we present an overview of the eight years of Dedal era. The amount of observing hours, number of meteors, statistics how many meteors were recognized using the automatic system MetRec or found manually, etc. are presented for each year. We also briefly overview the science results from these observations.
NEA rotations and binaries
Authors: Pravec Petr , Harris A. W. , Warner B. D.
Published: May 2007

Of the nearly 3900 near-Earth asteroids (NEAs) known as of June 2006, 325 have estimated rotation periods, with most of those determined by lightcurve analysis led by a few dedicated programs. NEAs with diameters down to 10 meters have been sampled. Observed spin distribution shows a major changing point around diameter of 200 meters. Larger NEAs show a barrier against spins faster than 11 d−1(period about 2.2 h) that shifts to slower rates (longer periods) with increasing lightcurve amplitude (i.e., with increasing equatorial elongation). The spin barrier is interpreted as a critical spin rate for bodies in a gravity regime; NEAs larger than 200 meters are predominantly bodies with tensile strength too low to withstand a centrifugal acceleration for rotation faster than the critical spin rate. The cohesionless spin barrier disappears at sizes less than 200 meters where most objects rotate too fast to be held together by self-gravitation only, so a cohesion is implied in the smaller NEAs.

The distribution of NEA spin rates in the cohesionless size range (D0.2 km) is highly non-Maxwellian, suggesting that mechanisms other than just collisions have been at work. There is a pile up just in front of the barrier, at periods 2–3 h. It may be related to a spin up mechanism crowding asteroids to the barrier. An excess of slow rotators is observed at periods longer than 30 hours. A spin-down mechanism has no obvious lower limit on spin rate; periods as long as tens of days have been observed.

Most NEAs appear to be in their basic spin states with rotation around principal axis with maximum moment of inertia. Tumbling objects (i.e., bodies in excited, non-principal axis rotation) are present and actually predominate among slow rotators with estimated damping timescales longer than the age of the solar system. A few tumblers observed among fast rotating coherent objects appear to be either more rigid or younger than the larger (cohesionless) tumblers.

An abundant population of binary systems has been found among NEAs. The fraction of binaries among NEAs larger than 0.3 km has been estimated to be 15 ± 4%. Primaries of binary systems concentrate at fast spin rates (periods 2–3 h) and low amplitudes, i.e., they lie just below the cohesionless spin barrier. The total angular momentum content in binary systems suggests that they formed from parent bodies spinning at the critical rate. The fact that a very similar population of binaries has been found among small main belt asteroids suggests a binary formation mechanism that may not be related to close encounters with the terrestrial planets.
Earth's 2006 encounter with comet 73P/Schwassmann-Wachmann: Products of nucleus fragmentation seen in closeup
Authors: Sekanina Zdeněk
Published: May 2007

The large numbers of nucleus fragments observed are a spectacular illustration of the process of cascading fragmentation in progress, a concept introduced to interpret the properties of the Kreutz system of sungrazers and comet D/1993 F2. The objective is to describe the fragmentation sequence and hierarchy of comet 73P, the nature of the fragmentation process and observed events, and the expected future evolution of this comet. The orbital arc populated by the fragments refers to an interval of 3.74 days in the perihelion time. This result suggests that they all could be products (but not necessarily first-generation fragments) of two 1995 events, in early September (involving an enormous outburst) and at the beginning of November. The interval of perihelion times is equivalent to a range of about 2.5 m/s in separation velocity or 0.00012 the Sun's attraction in nongravitational deceleration. Their combined effect suggests minor orbital momentum changes acquired during fragmentation and decelerations compatible with survival over two revolutions about the Sun. Fragment B is a likely first-generation product of one of the 1995 events. From the behavior of the primary fragment C, 73P is not a dying comet, even though fragment B and others were episodically breaking up into many pieces. Each episode began with the sudden appearance of a starlike nucleus condensation and a rapidly expanding outburst, followed by a development of jets, and a gradual tailward extension of the fading condensation, until the discrete masses embedded in it could be resolved. In April-May, this debris traveled first to the southwest, but models show their eventual motion toward the projected orbit. Fainter fragments were imaged over limited time, apparently because of their erratic activity (interspersed with periods of dormancy) rather than improptu disintegration. A dust trail joining the fragments and reminiscent of comet 141P/Machholz suggests that cascading fragmentation exerts itself profoundly over an extremely broad mass range of particulate debris.
Itokawa: The power of ground-based mid-infrared observations
Authors: Müller Thomas G. , Sekiguchi T. , Kaasalainen M. , Abe M. , Hasegawa S.
Published: May 2007

Pre-encounter ground-based thermal observations of NEA 25143 Itokawa at 10μm led to a size prediction of 520(±50) × 270(±30) × 230(±20)m, corresponding to an effective diameter of DTPMeff= 318m (Müller et al.2005). This is in almost perfect agreement with the final in-situ results 535 × 294 × 209m (DHayabusaeff= 320m; Demura et al.2006). The corresponding radar value, based on the same shape model (Kaasalainen et al.2005), were about 20% too high: 594 × 320 × 288m (DRadareff= 379m; Ostro et al.2005). The very simple N-band observations revealed a surface which is dominated by bare rocks rather than a thick regolith layer. This prediction was nicely confirmed by the Hayabusa mission (e.g., Fujiwara et al.2006; Saito et al.2006). The ground-based measurements covered three different phase angles which enabled us to determine the thermal properties with unprecedented accuracy and in excellent agreement with the results from the touch-down measurements (Okada et al.2006; Yano et al.2006). These thermal values are also key ingredients for high precision Yarkovsky and YORP calculations (mainly the rotation slowing) for Itokawa (e.g., Vokrouhlický et al.2004; Vokrouhlický et al.2005). In addition to the above mentioned properties, our data allowed us to derive the surface albedo and to estimate the total mass. We believe that with our well-tested and calibrated radiometric techniques (Lagerros 1996,1997,1998; Müller & Lagerros 1998, 2002; Müller 2002) we have tools at hand to distinguish between monolithic, regolith-covered and rubble pile near-Earth objects by only using remote thermal observations. This project also emphasizes the high and so far not yet fully exploited potential of thermophysical modeling techniques for the NEA/NEO exploration.
Current NEO surveys
Authors: Larson Stephen
Published: May 2007

The state and discovery rate of current NEO surveys reflect incremental improvements in a number of areas, such as detector size and sensitivity, computing capacity, detection software efficiency and availability of larger telescope apertures. The result has been an increase in the NEO discovery rate. There are currently eight telescopes ranging in size from 0.5-1.5 meters carrying out full-or part-time systematic surveying in both hemispheres. The sky is covered 1-2 times per lunation to V1~9, with a band near the ecliptic to V2~0.5. We review the current survey programs and their contributions towards the Spaceguard goal of discovering at least 90% of the NEOs larger than 1 km.
Searching for NEOs using Lowell observatorys Discovery Channel Telescope (DCT)
Authors: Bowell Edward , Millis Robert L. , Dunham Edward W. , Koehn Bruce W. , Smith Byron W.
Published: May 2007

We discuss the potential contribution of the Discovery Channel Telescope (or a clone) to a detection program aimed at discovering 90% of potentially hazardous objects (PHOs) larger than 140 m in diameter. Three options are described, each involving different levels of investment. We believe that LSST, Pan-STARRS, and DCT, working in a coordinated fashion, offer a cost-effective, low-risk way to accomplish the objectives of the extended NEO search program.
NEO search telescope in China
Authors: Ma Yuehua , Zhao Haibin , Yao Dazhi
Published: May 2007

Chinese scientists have contributed many research works to the field of asteroid surveying and related topics. In the early 1960s, Purple Mountain Observatory (PMO) began observing asteroids and found over 130 new numbered asteroids during the following decades. The Schmidt CCD Asteroid Program (SCAP) of Beijing Astronomical Observatory (BAO) started in 1995 and found 575 asteroids in several years.

NEOs represent a great threat to the near-Earth environment by closely approaching Earth or even impacting with Earth. After the impact of comet SL9 on Jupiter, Chinese proposed to build a NEO Search Telescope to take part in the joint international NEO survey. It is a 1.0/1.2 m Schmidt telescope with a 4K×4K drift scanning CCD detector. Here we elaborate upon its applications to objects of scientific interest, its parameters, and its observing station.
The UK Near Earth Object Information Centre (NEOIC)
Authors: Williams Iwan P.
Published: May 2007

Following the report of the ‘task force’, the UK Government decided to accept some of it's recommendations. In particular, it accepted two that recommended the setting up of a British National Centre for Near Earth Objects. The final outcome was the setting up of a Near Earth Object Information Centre to inform the general public of the dangers or otherwise from impact on the Earth of Near Earth Objects. The Centre has now been running for several years and in this publication we examine the current workings of the Centre and discuss some of its successes and failures.
A numerical method for simulating one‐dimensional headcut migration and overtopping breaching in cohesive and zoned embankments
Authors: Wang Zhengang , Bowles David S.
Published: May 2007

An erosion and force/moments equilibrium‐based numerical method is proposed to simulate one‐dimensional headcut migration in cohesive embankment overtopping breaches and to simulate the one‐dimensional breach process of zoned embankment dams before they fully breach through. At each time step of the simulation the depths and velocities of the breach outflow are calculated by solving the one‐dimensional shallow water equations, three‐dimensional slope stability is checked, and the eroded soil and instable soil block are removed. The method was tested using data from a U.S. Department of Agriculture Agricultural Research Service cohesive embankment and the Yahekou zoned fuse plug. Test results showed that the proposed method predicts well the one‐dimensional headcut shape in the cohesive dam and the breach shape in the zoned embankment dam provided that the inputs are appropriately assigned. Sensitivity studies showed that the breach processes for a weakly cohesive dam under a small overtopping depth and a highly cohesive dam are controlled by erosion only. They also showed that the breach processes for a weakly cohesive dam under a relatively large overtopping depth, a noncohesive dam, and a zoned embankment dam are all controlled by erosion and force/moments equilibrium.
Nitrification in the euphotic zone as evidenced by nitrate dual isotopic composition: Observations from Monterey Bay, California
Authors: Wankel Scott D. , Kendall Carol , Pennington J. Timothy , Chavez Francisco P. , Paytan Adina
Published: May 2007

Coupled measurements of nitrate (NO3−), nitrogen (N), and oxygen (O) isotopic composition (δ15NNO3 and δ18ONO3) were made in surface waters of Monterey Bay to investigate multiple N cycling processes occurring within surface waters. Profiles collected throughout the year at three sites exhibit a wide range of values, suggesting simultaneous and variable influence of both phytoplankton NO3− assimilation and nitrification within the euphotic zone. Specifically, increases in δ18ONO3 were consistently greater than those in δ15NNO3. A coupled isotope steady state box model was used to estimate the amount of NO3− supplied by nitrification in surface waters relative to that supplied from deeper water. The model highlights the importance of the branching reaction during ammonium (NH4+) consumption, in which NH4+ either serves as a substrate for regenerated production or for nitrification. Our observations indicate that a previously unrecognized proportion of nitrate‐based productivity, on average 15 to 27%, is supported by nitrification in surface waters and should not be considered new production. This work also highlights the need for a better understanding of isotope effects of NH4+ oxidation, NH4+ assimilation, and NO3− assimilation in marine environments.
East African lightning as a precursor of Atlantic hurricane activity
Authors: Price Colin , Yair Yoav , Asfur Mustafa
Published: May 2007

Recent years have shown the tremendous damage and loss of life that can be caused by Atlantic Basin hurricanes. The majority of these hurricanes start as African easterly waves (AEWs) over the African continent. In this paper we provide evidence showing the connection between lightning activity over eastern Africa, and the AEWs that leave the west coast of Africa, some of which develop into hurricanes. We have analyzed the 2005 and 2006 hurricane seasons, one a very active hurricane year (2005), and the other a very quiet year (2006). More than 90% of the tropical storms and hurricanes during these 2 years were preceded by periods of above average thunderstorm activity in eastern Africa. During the 2006 season not only was the east African lightning activity 23% lower than during 2005, but there was 36% less lightning activity over the entire African continent during 2006. We suggest the possibility that lightning activity in tropical Africa may represent an important precursor of Atlantic hurricane formation.
Large chemical ozone loss in 2004/2005 Arctic winter/spring
Authors: Feng W. , Chipperfield M. P. , Davies S. , von der Gathen P. , Kyrö E. , Volk C. M. , Ulanovsky A. , Belyaev G.
Published: May 2007

We have used a three‐dimensional chemical transport model to quantify Arctic ozone loss in 2004/2005 and compare it to other winters through 2006. Relative to Arctic stratospheric variability, 2004/05 was a very cold winter with large regions of possible NAT (nitric acid trihydrate) and ice polar stratospheric cloud formation. These areas were the largest during the past 12 years in January and the vortex area was similarly the largest in early March. Accordingly, the model produces strong denitrification, extensive chlorine activation and large chemical ozone loss of up 75% locally and ∼140 DU in the vortex‐averaged column, which slightly overestimates that derived from observations. Compared with similar calculations for recent years, 2004/05 compares with 1999/2000 as one of maximum modelled loss. Sensitivity experiments show that small regions of extreme ozone loss, near 100% at some altitudes, could have happened if the winter of 2004/05 was followed by a spring like 1997 with a long‐lasting cold polar vortex.
Mechanisms of formation of the Arabian Sea mini warm pool in a high‐resolution Ocean General Circulation Model
Authors: Kurian Jaison , Vinayachandran P. N.
Published: May 2007

An Ocean General Circulation Model of the Indian Ocean with high horizontal (0.25° × 0.25°) and vertical (40 levels) resolutions is used to study the dynamics and thermodynamics of the Arabian Sea mini warm pool (ASMWP), the warmest region in the northern Indian Ocean during January–April. The model simulates the seasonal cycle of temperature, salinity and currents as well as the winter time temperature inversions in the southeastern Arabian Sea (SEAS) quite realistically with climatological forcing. An experiment which maintained uniform salinity of 35 psu over the entire model domain reproduces the ASMWP similar to the control run with realistic salinity and this is contrary to the existing theories that stratification caused by the intrusion of low‐salinity water from the Bay of Bengal into the SEAS is crucial for the formation of ASMWP. The contribution from temperature inversions to the warming of the SEAS is found to be negligible. Experiments with modified atmospheric forcing over the SEAS show that the low latent heat loss over the SEAS compared to the surroundings, resulting from the low winds due to the orographic effect of Western Ghats, plays an important role in setting up the sea surface temperature (SST) distribution over the SEAS during November–March. During March–May, the SEAS responds quickly to the air‐sea fluxes and the peak SST during April–May is independent of the SST evolution during previous months. The SEAS behaves as a low wind, heat‐dominated regime during November–May and, therefore, the formation and maintenance of the ASMWP is not dependent on the near surface stratification.
Simulation of secular trends in the middle atmosphere, 1950–2003
Authors: Garcia R. R. , Marsh D. R. , Kinnison D. E. , Boville B. A. , Sassi F.
Published: May 2007

We have used the Whole Atmosphere Community Climate Model to produce a small (three‐member) ensemble of simulations of the period 1950–2003. Comparison of model results against available observations shows that for the most part, the model is able to reproduce well the observed trends in zonal mean temperature and ozone, both as regards their magnitude and their distribution in latitude and altitude. Calculated trends in water vapor, on the other hand, are not at all consistent with observations from either the HALOE satellite instrument or the Boulder, Colorado, hygrosonde data set. We show that such lack of agreement is actually to be expected because water vapor has various sources of low‐frequency variability (heating due to volcanic eruptions, the quasi‐biennial oscillation and El Niño–Southern Oscillation) that can confound the determination of secular trends. The simulations also reveal the presence of other interesting behavior, such as the lack of any significant temperature trend near the mesopause, a decrease in the stratospheric age of air, and the rare occurrence of an extremely disturbed Southern Hemisphere winter.
Seismic detection and analysis of icequakes at Columbia Glacier, Alaska
Authors: O'Neel Shad , Marshall H. P. , McNamara D. E. , Pfeffer W. T.
Published: May 2007

Contributions to sea level rise from rapidly retreating marine‐terminating glaciers are large and increasing. Strong increases in iceberg calving occur during retreat, which allows mass transfer to the ocean at a much higher rate than possible through surface melt alone. To study this process, we deployed an 11‐sensor passive seismic network at Columbia Glacier, Alaska, during 2004–2005. We show that calving events generate narrow‐band seismic signals, allowing frequency domain detections. Detection parameters were determined using direct observations of calving and validated using three statistical methods and hypocenter locations. The 1–3 Hz detections provide a good measure of the temporal distribution and size of calving events. Possible source mechanisms for the unique waveforms are discussed, and we analyze potential forcings for the observed seismicity.