453 research outputs found
Motion in Quantum Gravity
We tackle the question of motion in Quantum Gravity: what does motion mean at
the Planck scale? Although we are still far from a complete answer we consider
here a toy model in which the problem can be formulated and resolved precisely.
The setting of the toy model is three dimensional Euclidean gravity. Before
studying the model in detail, we argue that Loop Quantum Gravity may provide a
very useful approach when discussing the question of motion in Quantum Gravity.Comment: 30 pages, to appear in the book "Mass and Motion in General
Relativity", proceedings of the C.N.R.S. School in Orleans, France, eds. L.
Blanchet, A. Spallicci and B. Whitin
Giant Piloleiomyoma of the Forehead
Cutaneous piloleiomyomas are benign smooth muscle tumors arising from the arrector pili muscles. Piloleiomyomas appear as firm dermal papules of skin color or with a reddish to brown surface, and are commonly located on the extremities. Histologically, these lesions are composed of interlacing bundles of smooth muscle cells in the reticular dermis. Our case presented with an unusually large nodule on the forehead that was accompanied by intermittent pain. Histological analysis was compatible with piloleiomyoma and the lesion showed haphazardly arranged bundles of smooth muscle in the dermis. We describe herein an interesting case of a giant piloleiomyoma occurring on the forehead
Environmental Control of Phase Transition and Polyp Survival of a Massive-Outbreaker Jellyfish
A number of causes have been proposed to account for the occurrence of gelatinous zooplankton (both jellyfish and ctenophore) blooms. Jellyfish species have a complex life history involving a benthic asexual phase (polyp) and a pelagic sexual phase (medusa). Strong environmental control of jellyfish life cycles is suspected, but not fully understood. This study presents a comprehensive analysis on the physicochemical conditions that control the survival and phase transition of Cotylorhiza tuberculata; a scyphozoan that generates large outbreaks in the Mediterranean Sea. Laboratory experiments indicated that the influence of temperature on strobilation and polyp survival was the critical factor controlling the capacity of this species to proliferate. Early life stages were less sensitive to other factors such as salinity variations or the competitive advantage provided by zooxanthellae in a context of coastal eutrophication. Coherently with laboratory results, the presence/absence of outbreaks of this jellyfish in a particular year seems to be driven by temperature. This is the first time the environmental forcing of the mechanism driving the life cycle of a jellyfish has been disentangled via laboratory experimentation. Projecting this understanding to a field population under climatological variability results in a pattern coherent with in situ records
An investigation on the presence of Chlamydiaceae in Swedish dogs
<p>Abstract</p> <p>Background</p> <p>Bacteria belonging to the family <it>Chlamydiaceae </it>cause a broad spectrum of diseases in a wide range of hosts, including man, other mammals, and birds. Upper respiratory and genital diseases are common clinical problems caused by <it>Chlamydiaceae</it>. Very little is known about chlamydial infections in dogs. Few clinical reports on natural disease in dogs describe mainly conjunctival and upper respiratory signs, and the role of <it>Chlamydiaceae </it>in genital disease is unclear. The present study aimed at studying the prevalence of <it>Chlamydiaceae </it>in healthy dogs and in dogs with genital or upper respiratory disease, including conjunctivitis.</p> <p>Methods</p> <p>A real-time polymerase chain reaction (PCR) for <it>Chlamydiaceae </it>was used to detect any chlamydial species within this family. Swab samples from the conjunctiva and the mucosal membranes of the oropharynx, rectum and genital tract were taken from 79 dogs: 27 clinically healthy dogs, 25 dogs with clinical signs from the genital tract and 28 dogs with conjunctivitis. There were 52 female and 27 male dogs. From 7 of the male dogs, additional semen samples were analysed.</p> <p>Results</p> <p>No <it>Chlamydiaceae </it>were detected from any dog.</p> <p>Conclusions</p> <p>Although the number of dogs that was included is limited, the results suggest that cases of <it>Chlamydiaceae </it>in dogs probably are related to infection from other species, and that dogs in general do not harbour <it>Chlamydiaceae</it>. Bacteria belonging to the family <it>Chlamydiaceae </it>do not seem to be of major importance for genital or ocular disease in Swedish dogs.</p
Biomass of Scyphozoan Jellyfish, and Its Spatial Association with 0-Group Fish in the Barents Sea
An 0-group fish survey is conducted annually in the Barents Sea in order to estimate fish population abundance. Data on jellyfish by-catch have been recorded since 1980, although this dataset has never been analysed. In recent years, however, the ecological importance of jellyfish medusae has become widely recognized. In this paper the biomass of jellyfish (medusae) in 0–60 m depths is calculated for the period 1980–2010. During this period the climate changed from cold to warm, and changes in zooplankton and fish distribution and abundance were observed. This paper discusses the less well known ecosystem component; jellyfish medusae within the Phylum Cnidaria, and their spatial and temporal variation. The long term average was ca. 9×108 kg, with some years showing biomasses in excess of 5×109 kg. The biomasses were low during 1980s, increased during 1990s, and were highest in early 2000s with a subsequent decline. The bulk of the jellyfish were observed in the central parts of the Barents Sea, which is a core area for most 0-group fishes. Jellyfish were associated with haddock in the western area, with haddock and herring in the central and coastal area, and with capelin in the northern area of the Barents Sea. The jellyfish were present in the temperature interval 1°C<T<10°C, with peak densities at ca. 5.5°C, and the greatest proportion of the jellyfish occurring between 4.0–7.0°C. It seems that the ongoing warming trend may be favourable for Barents Sea jellyfish medusae; however their biomass has showed a recent moderate decline during years with record high temperatures in the Barents Sea. Jellyfish are undoubtedly an important component of the Barents Sea ecosystem, and the data presented here represent the best summary of jellyfish biomass and distribution yet published for the region
Morbidity, Including Fatal Morbidity, throughout Life in Men Entering Adult Life as Obese
Background: The association between obesity in adults and excess morbidity and mortality is well established, but the health impact throughout adult life of being obese in early adulthood needs elucidation. We investigated somatic morbidity, including fatal morbidity, throughout adulthood in men starting adult life as obese. Methods: Among 362,200 Danish young men, examined for military service between 1943 and 1977, all obese (defined as BMI$31.0 kg/m 2), and, as controls, a random 1 % sample of the others was identified. In the age range of 18–25 years, there were 1,862 obese, which encompass the men above the 99.5 percentile, and 3,476 controls. Information on morbidity was obtained via national registers. Cox regression models were used to estimate the relative morbidity assessed as first incidence of disease, occurrence of disease in the year preceding death and prevalent disease at time of death. Results: From age 18 through 80 years the obese had an increased risk of becoming diseased by or die from a broad range of diseases. Generally, the incidence of first event, occurrence in the year prior to death, and prevalence at time of death showed the same pattern. As an example, the relative hazard of type 2 diabetes was constant throughout life at 4.9 (95% confidence intervals [CI]: 4.1–5.9), 5.2 (95 % CI: 3.6–7.5), and 6.8 (95 % CI: 4.6–10.1), respectively. Conclusions: Our findings strongly support the continued need to avoid beginning adult life as obese, as obese young me
Brain Imaging Studies in Pathological Gambling
This article reviews the neuroimaging research on pathological gambling (PG). Because of the similarities between substance dependence and PG, PG research has used paradigms similar to those used in substance use disorder research, focusing on reward and punishment sensitivity, cue reactivity, impulsivity, and decision making. This review shows that PG is consistently associated with blunted mesolimbic-prefrontal cortex activation to nonspecific rewards, whereas these areas show increased activation when exposed to gambling-related stimuli in cue exposure paradigms. Very little is known, and hence more research is needed regarding the neural underpinnings of impulsivity and decision making in PG. This review concludes with a discussion regarding the challenges and new developments in the field of neurobiological gambling research and comments on their implications for the treatment of PG
Altered orbitofrontal sulcogyral patterns in gambling disorder: a multicenter study
Gambling disorder is a serious psychiatric condition characterized by decision-making and reward processing
impairments that are associated with dysfunctional brain activity in the orbitofrontal cortex (OFC). However, it remains
unclear whether OFC functional abnormalities in gambling disorder are accompanied by structural abnormalities. We
addressed this question by examining the organization of sulci and gyri in the OFC. This organization is in place very
early and stable across life, such that OFC sulcogyral patterns (classified into Types I, II, and III) can be regarded as
potential pre-morbid markers of pathological conditions. We gathered structural brain data from nine existing studies,
reaching a total of 165 individuals with gambling disorder and 159 healthy controls. Our results, supported by both
frequentist and Bayesian statistics, show that the distribution of OFC sulcogyral patterns is skewed in individuals with
gambling disorder, with an increased prevalence of Type II pattern compared with healthy controls. Examination of
gambling severity did not reveal any significant relationship between OFC sulcogyral patterns and disease severity.
Altogether, our results provide evidence for a skewed distribution of OFC sulcogyral patterns in gambling disorder and
suggest that pattern Type II might represent a pre-morbid structural brain marker of the disease. It will be important to
investigate more closely the functional implications of these structural abnormalities in future work.Y.L. was supported by the National Natural Science Foundation of China (Grant
No. 31600929) and the Fundamental Research Funds for the Central
Universities (010914380002). G.S. was supported by a Veni grant from the
Netherlands Organization for Scientific Research (Grant No. 016.155.218). J.J.
was supported by the Academy of Finland (Grant No. 295580), the Finnish
Medical Foundation, and the Finnish Foundation for Alcohol Studies. V.K. was
supported by the Academy of Finland (Grant No. 256836) and the Finnish
Foundation for Alcohol Studies. S.G. and H.R.S. were supported by the Danish
Council for Independent Research in Social Sciences through a grant to
Thomas Ramsøy (“Decision Neuroscience Project”; Grant No. 0601-01361B) and
by the Lundbeck Foundation through a Grant of Excellence (“ContAct”; Grant
No. R59 A5399). A.G. was supported by Deutsche Forschungsgemeinschaft
(DFG) HE2597/15–1, HE2597/15–2, and DFG Graduiertenkolleg 1589/2 “Sensory
Computation in Neural Systems”. N.R.-S. was supported by a research grant by
the Senatsverwaltung für Gesundheit und Soziales, Berlin, Germany (Grant No.
002–2008/I B 35). C.M.R.d.L. and J.C.P. were supported by a grant from the
Spanish Government (Ministerio de Economía y Competitividad, Secretaría de
Estado de Investigación, Desarrollo e Innovación; Convocatoria 2017 de
Proyectos I+D de Excelencia, Spain; co-funded by the Fondo Europeo de
Desarrollo Regional, FEDER, European Union; Grant No. PSI2017–85488-P). J.-C.
D. was supported by “LABEX ANR-11-LABEX-0042” of Université de Lyon within
the program Investissements d’Avenir (ANR-11-IDEX-007) operated by the
French National Research Agency and by a grant from the Fondation pour la
Recherche Médicale (Grant No. DPA20140629796)
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