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Change history: In this Letter, the Acknowledgements section should have included the following sentence: "The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.". This omission has been corrected online.
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Massive galaxy clusters have been found that date to times as early as three billion years after the Big Bang, containing stars that formed at even earlier epochs1-3. The high-redshift progenitors of these galaxy clusters-termed 'protoclusters'-can be identified in cosmological simulations that have the highest overdensities (greater-than-average densities) of dark matter4-6. Protoclusters are expected to contain extremely massive galaxies that can be observed as luminous starbursts 7 . However, recent detections of possible protoclusters hosting such starbursts8-11 do not support the kind of rapid cluster-core formation expected from simulations 12 : the structures observed contain only a handful of starbursting galaxies spread throughout a broad region, with poor evidence for eventual collapse into a protocluster. Here we report observations of carbon monoxide and ionized carbon emission from the source SPT2349-56. We find that this source consists of at least 14 gas-rich galaxies, all lying at redshifts of 4.31. We demonstrate that each of these galaxies is forming stars between 50 and 1,000 times more quickly than our own Milky Way, and that all are located within a projected region that is only around 130 kiloparsecs in diameter. This galaxy surface density is more than ten times the average blank-field value (integrated over all redshifts), and more than 1,000 times the average field volume density. The velocity dispersion (approximately 410 kilometres per second) of these galaxies and the enormous gas and star-formation densities suggest that this system represents the core of a cluster of galaxies that was already at an advanced stage of formation when the Universe was only 1.4 billion years old. A comparison with other known protoclusters at high redshifts shows that SPT2349-56 could be building one of the most massive structures in the Universe today.
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According to the current understanding of cosmic structure formation, the precursors of the most massive structures in the Universe began to form shortly after the Big Bang, in regions corresponding to the largest fluctuations in the cosmic density field. Observing these structures during their period of active growth and assembly-the first few hundred million years of the Universe-is challenging because it requires surveys that are sensitive enough to detect the distant galaxies that act as signposts for these structures and wide enough to capture the rarest objects. As a result, very few such objects have been detected so far. Here we report observations of a far-infrared-luminous object at redshift 6.900 (less than 800 million years after the Big Bang) that was discovered in a wide-field survey. High-resolution imaging shows it to be a pair of extremely massive star-forming galaxies. The larger is forming stars at a rate of 2,900 solar masses per year, contains 270 billion solar masses of gas and 2.5 billion solar masses of dust, and is more massive than any other known object at a redshift of more than 6. Its rapid star formation is probably triggered by its companion galaxy at a projected separation of 8 kiloparsecs. This merging companion hosts 35 billion solar masses of stars and has a star-formation rate of 540 solar masses per year, but has an order of magnitude less gas and dust than its neighbour and physical conditions akin to those observed in lower-metallicity galaxies in the nearby Universe. These objects suggest the presence of a dark-matter halo with a mass of more than 100 billion solar masses, making it among the rarest dark-matter haloes that should exist in the Universe at this epoch.
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In the past decade, our understanding of galaxy evolution has been revolutionized by the discovery that luminous, dusty starburst galaxies were 1,000 times more abundant in the early Universe than at present. It has, however, been difficult to measure the complete redshift distribution of these objects, especially at the highest redshifts (z > 4). Here we report a redshift survey at a wavelength of three millimetres, targeting carbon monoxide line emission from the star-forming molecular gas in the direction of extraordinarily bright millimetre-wave-selected sources. High-resolution imaging demonstrates that these sources are strongly gravitationally lensed by foreground galaxies. We detect spectral lines in 23 out of 26 sources and multiple lines in 12 of those 23 sources, from which we obtain robust, unambiguous redshifts. At least 10 of the sources are found to lie at z > 4, indicating that the fraction of dusty starburst galaxies at high redshifts is greater than previously thought. Models of lens geometries in the sample indicate that the background objects are ultra-luminous infrared galaxies, powered by extreme bursts of star formation.
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In the cores of some clusters of galaxies the hot intracluster plasma is dense enough that it should cool radiatively in the cluster's lifetime, leading to continuous 'cooling flows' of gas sinking towards the cluster centre, yet no such cooling flow has been observed. The low observed star-formation rates and cool gas masses for these 'cool-core' clusters suggest that much of the cooling must be offset by feedback to prevent the formation of a runaway cooling flow. Here we report X-ray, optical and infrared observations of the galaxy cluster SPT-CLJ2344-4243 (ref. 11) at redshift z = 0.596. These observations reveal an exceptionally luminous (8.2 × 10(45) erg s(-1)) galaxy cluster that hosts an extremely strong cooling flow (around 3,820 solar masses a year). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (formation of around 740 solar masses a year), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool-core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star-formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form through accretion of the intracluster medium, rather than (as is currently thought) assembling entirely via mergers.
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Although electroconvulsive therapy (ECT) is one of the most effective treatments for severe mood and psychotic disorders, the mechanisms underlying its therapeutic effects remain unknown. Electroconvulsive stimulation (ECS), the animal model for ECT, can be used to investigate the potential therapeutic mechanisms of ECT in rodents. ECS produces numerous effects in the brain, such as increasing levels of growth factors, inducing dendritic sprouting, and stimulating neurogenesis. It also induces high-level expression of immediate early genes (IEGs) that have been implicated in the pathogenesis of schizophrenia, such as early growth response 3 (Egr3) and activity-regulated cytoskeleton-associated protein (Arc), a validated downstream target of Egr3 [1-3]. However, the effect of isoflurane anesthesia preceding ECS on IEG response in mice has not been well characterized. This article provides immunofluorescent data of the activity responsive IEG ARC in the dorsal and ventral dentate gyrus of wildtype (WT) mice following ECS with or without anesthesia, as well as following sham ECS. The data in this article relate to a published article that employed serial ECS in mice to investigate the requirement of Egr3 in the neurobiological effects of this model of ECT [4]. The ability to study the effects of serial ECS has been limited in mice due to high rates of mortality during seizure. Administration of isoflurane anesthesia prior to ECS significantly reduces rodent mortality, irrespective of the number of times ECS is applied [5]. Since general anesthesia is administered to patients prior to ECT, use of isoflurane prior to ECS also more closely models the clinical use of ECT [6].
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BACKGROUND: Despite being one of the safest, most effective treatments for severe mood disorders, the therapeutic mechanisms of electroconvulsive therapy remain unknown. Electroconvulsive seizure (ECS) induces rapid, high-level expression of immediate early genes (IEGs) and brain-derived neurotrophic factor (BDNF), in addition to stimulation of neurogenesis and dendritic remodeling of dentate gyrus (DG) neurons. We have previously shown that this upregulation of BDNF fails to occur in the hippocampus of mice lacking the IEG Egr3. Since BDNF influences neurogenesis and dendritic remodeling, we hypothesized that Egr3-/- mice will exhibit deficits in neurogenesis and dendritic remodeling in response to ECS. OBJECTIVE: To test this hypothesis, we examined dendritic remodeling and cellular proliferation in the DG of Egr3-/- and wild-type mice following repeated ECS. METHODS: Mice received 10 daily ECSs. Dendritic morphology was examined in Golgi-Cox-stained tissue and cellular proliferation was analyzed through bromodeoxyuridine (BrdU) immunohistochemistry and confocal imaging. RESULTS: Serial ECS in mice results in dendritic remodeling, increased spine density, and cellular proliferation in the DG. Loss of Egr3 alters the dendritic remodeling induced by serial ECS but does not change the number of dendritic spines or cellular proliferation consequences of ECS. CONCLUSION: Egr3 influences the dendritic remodeling induced by ECS but is not required for ECS-induced proliferation of hippocampal DG cells.
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Factor Neurotrófico Derivado del Encéfalo , Hipocampo , Ratones , Animales , Factor Neurotrófico Derivado del Encéfalo/genética , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Hipocampo/fisiología , Convulsiones/metabolismo , Proliferación Celular , Neurogénesis/fisiología , Giro Dentado/fisiologíaRESUMEN
Increased excitability and plasticity of adult-generated hippocampal granule cells during a critical period suggests that they may "orthogonalize" memories according to time. One version of this "temporal tag" hypothesis suggests that young granule cells are particularly responsive during a specific time period after their genesis, allowing them to play a significant role in sculpting CA3 representations, after which they become much less responsive to any input. An alternative possibility is that the granule cells active during their window of increased plasticity, and excitability become selectively tuned to events that occurred during that time and participate in later reinstatement of those experiences, to the exclusion of other cells. To discriminate between these possibilities, rats were exposed to different environments at different times over many weeks, and cell activation was subsequently assessed during a single session in which all environments were revisited. Dispersing the initial experiences in time did not lead to the increase in total recruitment at reinstatement time predicted by the selective tuning hypothesis. The data indicate that, during a given time frame, only a very small number of granule cells participate in many experiences, with most not participating significantly in any. Based on these and previous data, the small excitable population of granule cells probably correspond to the most recently generated cells. It appears that, rather than contributing to the recollection of long past events, most granule cells, possibly 90-95%, are effectively "retired." If granule cells indeed sculpt CA3 representations (which remains to be shown), then a possible consequence of having a new set of granule cells participate when old memories are reinstated is that new representations of these experiences might be generated in CA3. Whatever the case, the present data may be interpreted to undermine the standard "orthogonalizer" theory of the role of the dentate gyrus in memory.
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Región CA3 Hipocampal/citología , Región CA3 Hipocampal/fisiología , Neurogénesis/fisiología , Neuronas/citología , Neuronas/fisiología , Animales , Electrochoque , Ambiente Controlado , Masculino , Memoria/fisiología , Modelos Neurológicos , Plasticidad Neuronal/fisiología , Ratas , Ratas Endogámicas F344 , Factores de TiempoRESUMEN
Sgr A*, the supermassive black hole (SMBH) at the center of our Milky Way Galaxy, is known to be a variable source of X-ray, near-infrared (NIR), and submillimeter radiation and therefore a prime candidate to study the electromagnetic radiation generated by mass accretion flow onto a black hole and/or a related jet. Disentangling the power source and emission mechanisms of this variability is a central challenge to our understanding of accretion flows around SMBHs. Simultaneous multiwavelength observations of the flux variations and their time correlations can play an important role in obtaining a better understanding of possible emission mechanisms and their origin. This paper presents observations of two flares that both apparently violate the previously established patterns in the relative timing of submillimeter/NIR/X-ray flares from Sgr A*. One of these events provides the first evidence of coeval structure between NIR and submillimeter flux increases, while the second event is the first example of the sequence of submillimeter/X-ray/NIR flux increases all occurring within ~1 hr. Each of these two events appears to upend assumptions that have been the basis of some analytic models of flaring in Sgr A*. However, it cannot be ruled out that these events, even though unusual, were just coincidental. These observations demonstrate that we do not fully understand the origin of the multiwavelength variability of Sgr A* and show that there is a continued and important need for long-term, coordinated, and precise multiwavelength observations of Sgr A* to characterize the full range of variability behavior.
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Galaxies grow inefficiently, with only a small percentage of the available gas converted into stars each free-fall time. Feedback processes, such as outflowing winds driven by radiation pressure, supernovae, or supermassive black hole accretion, can act to halt star formation if they heat or expel the gas supply. We report a molecular outflow launched from a dust-rich star-forming galaxy at redshift 5.3, 1 billion years after the Big Bang. The outflow reaches velocities up to 800 kilometers per second relative to the galaxy, is resolved into multiple clumps, and carries mass at a rate within a factor of 2 of the star formation rate. Our results show that molecular outflows can remove a large fraction of the gas available for star formation from galaxies at high redshift.
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Cardiovascular disease (CVD) remains the main cause of morbidity and mortality in patients with end-stage renal disease (ESRD). Traditional risk factors are common in ESRD patients, but they alone may not be sufficient to account for the high prevalence of CVD in this population. Recent clinical evidence demonstrates that chronic inflammation, a non traditional risk factor which is commonly observed in ESRD patients, may be associated with the presence of poor nutritional parameters and progressive atherosclerotic CVD. Based on these observations, the presence in ESRD patients of a syndrome consisting in malnutrition, signs of systemic chronic inflammation and atherosclerosis (MIA syndrome) has recently been suggested. A central role in this syndrome is played by the proinflammatory cytokines generated in response to factors such as chronic renal failure and infectious-inflammatory co-morbid disease. It is now clear that the immune response, both innate and adaptive, is the main cause of inflammation characterising atherosclerosis. As there is as yet no recognized, or even proposed, treatment for ESRD patients with chronic inflammation, it would be of obvious interest to study the long-term effect of various inflammatory treatment strategies on the nutritional and cardiovascular status as well as the outcome in these patients.
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Enfermedades Cardiovasculares/etiología , Inflamación/etiología , Fallo Renal Crónico/complicaciones , Diálisis Renal , Anciano , Arteriosclerosis/etiología , Enfermedad Crónica , Femenino , Humanos , Fallo Renal Crónico/terapia , Masculino , Desnutrición/etiología , Persona de Mediana Edad , Factores de RiesgoRESUMEN
The deep changes in values, beliefs and behaviour, both individual and group, have been examined, referred to the sexuality, by various methods and prospects. Sexual differentiation, typical of the plast, has been rediscussed and modified. As a result of these changes we can talk about old myths, concerning the conception of sexuality in the past, and new myths that concern the present. In this work we have reviewed the different aspects of male and female roles: masturbation, the obsession abort performance, the orgasm and, not last, the sexuality in old age condition.