Graphs with the strong Havel-Hakimi property

The Havel-Hakimi algorithm iteratively reduces the degree sequence of a graph to a list of zeroes. As shown by Favaron, Mah\'eo, and Sacl\'e, the number of zeroes produced, known as the residue, is a lower bound on the independence number of the graph. We say that a graph has the strong Havel-Hakimi property if in each of its induced subgraphs, deleting any vertex of maximum degree reduces the degree sequence in the same way that the Havel-Hakimi algorithm does. We characterize graphs having this property (which include all threshold and matrogenic graphs) in terms of minimal forbidden induced subgraphs. We further show that for these graphs the residue equals the independence number, and a natural greedy algorithm always produces a maximum independent set.Comment: 7 pages, 3 figure

Inextendibility of spacetimes and Lorentzian length spaces

We study the low-regularity (in-)extendibility of spacetimes within the synthetic-geometric framework of Lorentzian length spaces developed in [KS:17]. To this end, we introduce appropriate notions of geodesics and timelike geodesic completeness and prove a general inextendibility result. Our results shed new light on recent analytic work in this direction and, for the first time, relate low-regularity inextendibility to (synthetic) curvature blow-up.Comment: 21 pages, 1 figure, made assumptions in 5.4 and 5.6 more explicit (strong causality and local TL geodesic connectedness of extension

The Hawking-Penrose singularity theorem for C1,1C^{1,1}-Lorentzian metrics

We show that the Hawking--Penrose singularity theorem, and the generalisation of this theorem due to Galloway and Senovilla, continue to hold for Lorentzian metrics that are of $C^{1, 1}$-regularity. We formulate appropriate weak versions of the strong energy condition and genericity condition for $C^{1,1}$-metrics, and of $C^0$-trapped submanifolds. By regularisation, we show that, under these weak conditions, causal geodesics necessarily become non-maximising. This requires a detailed analysis of the matrix Riccati equation for the approximating metrics, which may be of independent interest.Comment: Minor amendments in v4: Removed non-equivalent condition from Def. 2.2 and adapted Lemma 3.5 and the proof of Lemma 3.

THE SPECIAL SAFEGUARD MECHANISM IN THE DOHA DEVELOPMENT AGENDA: A CASE STUDY OF SOYBEANS

The Special Safeguard Mechanism (SSM) proposed for developing countries has become a thorny issue in the Doha Development Agenda’s (DDA) agricultural negotiations. Proponents of the mechanism argue that it is a necessary compromise to counter sharp price declines or rapid import surges in staple commodity markets of developing nations. Opponents of the SSM, which include many developed exporters, contend that the policy flexibility contained in current SSM proposals would severely limit market access if the mechanism is triggered. The impact of the SSM depends on a number of parameters: the number of times the SSM is triggered, whether the price or volume SSM is triggered, the size of current tariffs, the magnitude with which tariffs are reduced in the DDA, and the number of times a developing country will actually make use of the SSM. This study introduces a static, synthetic, global, partial equilibrium model of the world soybean complex to assess the preliminary aspects of the DDA’s proposed tariff cuts. Future work on this project will extend the model to a stochastic framework from which to simulate the effects of an SSM combined with the DDA tariff cutting formulas for developing nations.Agribusiness,

A Study of Factors That Influence the Swimming Performance of Hispanic High School Students

The purpose of this study was to determine the relationship of swimming performance to six factors including, swimming self-efficacy, fear of drowning, perceived swimming risk, previous swimming opportunities, body image, and perceived athletic skills among high school Hispanic/Latino males and females, ages 13-18. This research also compared differences for each of the variables based on gender. Participants in the study included 71 females and 73 males, ages 13-18, all of Hispanic/Latino ethnic background from one high school. Swimming performance was measured by a Swimming Self-Efficacy Scale. Perceived swimming risk was determined by The Perception of Drowning Risk Survey. Body image, previous swimming opportunities, fear of drowning, and perceived athletic skill were assessed through additional survey questions. Analysis of variance determined if there were significant differences in the means of the seven tests based on gender. Males demonstrated significantly higher means for each variable. Relationships between swimming performance and the other variables were calculated sing Pearson Product Moment Correlations. Swimming self-efficacy and swimming performance had the strongest positive correlation (+ 0.75). There was a moderate negative correlation between fear of drowning and swimming self-efficacy (-0.54). Early multilevel swimming programs for all children are strongly encouraged to help children overcome fear of the water, increase swimming efficacy, swimming performance, and ultimately, to increase the percentage of adult who can swim

An Adaptation Level Theory of Tinnitus Audibility

Models of tinnitus suggest roles for auditory, attention, and emotional networks in tinnitus perception. A model of tinnitus audibility based on Helson’s (1964) adaptation level theory (ALT) is hypothesized to explain the relationship between tinnitus audibility, personality, memory, and attention. This theory attempts to describe how tinnitus audibility or detectability might change with experience and context. The basis of ALT and potential role of auditory scene analysis in tinnitus perception are discussed. The proposed psychoacoustic model lends itself to incorporation into existing neurophysiological models of tinnitus perception. It is hoped that the ALT hypothesis will allow for greater empirical investigation of factors influencing tinnitus perception, such as attention and tinnitus sound therapies

Everything old is new again: Finding a place for knowledge structures in a satisficing world

The authors use an exploratory project involving Web resources related to Alzheimer’s Disease to explore ways in RDF metadata can more effectively translate the virtues of the traditional vertical file to a Web environment form using Semantic Web descriptive standards. In so doing, they argue against the separation of “bibliographic control” from the socially-embedded institutional practices of reference work, collection development, and the management of information ephemera. Libraries of the future will use specific Web technologies that lend themselves to sophisticated and rigorous knowledge structures, and link them with librarians’ skills in information harvesting and evaluatio

Natural Killer Cell Function and Dysfunction in Hepatitis C Virus Infection

Viruses must continually adapt against dynamic innate and adaptive responses of the host immune system to establish chronic infection. Only a small minority (∼20%) of those exposed to hepatitis C virus (HCV) spontaneously clear infection, leaving approximately 200 million people worldwide chronically infected with HCV. A number of recent research studies suggest that establishment andmaintenance of chronicHCVinfection involve natural killer (NK) cell dysfunction. This relationship is illustrated in vitro by disruption of typicalNK cell responses including both cell-mediated cytotoxicity and cytokine production. Expression of a number of activating NK cell receptors in vivo is also affected in chronic HCV infection.Thus, direct in vivo and in vitro evidence of compromised NK function in chronic HCV infection in conjunction with significant epidemiological associations between the outcome of HCV infection and certain combinations of NK cell regulatory receptor and class I human histocompatibility linked antigen (HLA) genotypes indicate that NK cells are important in the immune response against HCV infection. In this review, we highlight evidence suggesting that selective impairment of NK cell activity is related to establishment of chronic HCV infection

Testing of Noodle Creek Site 41JS102 Jones County, Texas

Staff Archeologists from the Environmental Affairs Division of Texas Department of Transportation discovered buried cultural resources that constitute archeological site 41JS102, in June and July 2001 at the proposed location of a bridge replacement over Noodle Creek in Jones County, Texas. Shovel testing and backhoe trenching revealed cultural material at 65 cm below the surface. Following this discovery the Texas Department of Transportation made recommendations to the Texas Historical Commission to assess site 41JS 102 and they concurred. In September 2001 archeologists from the Texas Department of Transportation initiated the site assessment phase. Landowner complications halted that work before completion. Subsequently, TRC Environmental was provided a Work Authorization under an existing general services contract to complete the assessment of 41JS102 in December 2001. The fieldwork consisted of the hand excavation and documentation of eight 1 by 1 m test units and the digging and documenting of six backhoe trenches. Limited and scattered historic artifacts were recovered from the upper parts of the two alluvial terraces (T0 and T1). A prehistoric component with quantities of lithic debitage and sparse burned rocks, limited stone tools and mussel shells, and one possible cultural feature were encountered in a sloping, but well defined 10 to 15 cm thick zone in the T1 deposits. The Principal Investigator recommended prehistoric site 4 1JS102 was eligible for inclusion in the National Register of Historic Places and as a State Archeological Landmark. However, the staff at Texas Department of Transportation disagreed with that recommendation and presented an opposing case to the Texas Historical Commission who concurred with the Texas Department of Transportation\u27s recommendations. Consequently, no further archeological investigations will occur prior to the proposed development