Peripheral Nucleus Research Articles

STRUCTURAL ORGANIZATION OF THE MARGINAL AND THORACIC NUCLEI OF THE POSTERIOR HORNS OF THE HUMAN SPINAL CORD IN THE PRENATAL PERIOD

Background. Embryology is the fundamental study that provides insights into the formation stages of the central nervous system and the mechanisms involved in its development. Thus, we can establish clear time intervals for thoracic and marginal nuclei formation during intrauterine development. Aim: To investigate the morphogenesis of the marginal and thoracic nuclei of the posterior horns of the human spinal cord during intrauterine development. Results. In the period of 7-8 weeks of gestation, the first signs of the formation of the thoracic nucleus appear, while for the marginal - 9-10 weeks of gestation. Glial cells are companion cells that always surround neurons. In turn, the cells of each nucleus are characterized by uniformity and similarity in shape and size. At 11-12 weeks of gestation, the thoracic nucleus acquires a typical oval shape. The marginal nucleus begins to separate from the gelatinous substance. Clear boundaries of the thoracic nucleus with its inherent oval shape, in comparison with the marginal one, are formed earlier. We found them in 14-15 weeks of gestation. At the same time, the marginal nucleus is separated from the surrounding structures in 20-21 weeks of gestation. By 29-30 weeks, the thoracic and marginal nuclei finish forming boundaries and occupy positions according to the topography, but the process of neuronal differentiation continues until birth. Conclusion. Understanding the stages of fetal development is critical for ensuring healthy pregnancies. So, considering the data we obtained, it became clear that the thoracic nucleus begins to form earlier than the marginal one. The difference in period is on average 3-4 weeks of gestation. Later, the thoracic nucleus acquires its characteristic shape, while the peripheral nucleus begins to separate from the surrounding tissues. The 29-30th week of gestation is characterized by the completion of the formation of both nuclei and their location by their inherent topography.

Excitation Function of Freeze-Out Parameters in Symmetric Nucleus–Nucleus and Proton–Proton Collisions at the Same Collision Energy

We analyze the transverse momentum (pT) spectra of π+, π−, K+, K−, p, p¯, Λ, Λ¯, Ξ, Ξ¯, Ω−, Ω¯+ or Ω−+Ω¯+ in different centrality intervals in gold–gold (Au–Au) and lead–lead (Pb–Pb) symmetric collisions at 200 GeV and 2.76 TeV, respectively, by Tsallis–Pareto-type function. Proton–proton collisions at the same centre of mass energies are also analyzed for these particles to compare the results obtained from these systems. The present work extracts the effective temperature T, non-extensivity parameter (q), the mean transverse momentum spectra (⟨pT⟩), the multiplicity parameter (N0), kinetic freeze-out temperature (T0) and transverse flow velocity (βT). We reported a plateau structure of pT, T, T0, βT, pT and q in central collisions. Beyond the plateau region, the excitation function of all the above parameters decreases towards the periphery, except q, which has a reverse trend. The multiplicity parameter is also extracted, which is found to be decreasing towards the periphery from the central collisions. In addition, we observed that the excitation function of pp collisions is nearly the same to that of the most peripheral symmetric nucleus–nucleus collisions at the same colliding energy. Throughout the analyses, the same multiplicity parameters for particles and their antiparticles have been reported, which show the symmetric production of particles and their antiparticles.

Morphoanatomy, histochemical and secretions process of extrafloral nectaries in Joannesia princeps Vell. (Euphorbiaceae)

Joannesia princeps presents two acropetiolar glands, with topography and morphology similar to extrafloral nectaries (EFNs). In the present study we described the anatomy and the ultrastructure of acropetiolar glands, and analyzed the histochemistry and chemical composition of secretion in order to (i) verify if these glands are nectaries and (ii) understand the complexity of secretion and the cell compartment involved with the production and exudation. The samples were processed according to the standard methodology for anatomical and ultrastructural studies. The gland has uniseriate epidermis composed by palisade secretory cells. The secretion produced by the secretory epidermis is accumulated in a subcuticular space, which causes distention of the cuticle until it be broken, allowing the exudation. Xylem and phloem vascularize the gland, with the phloem reaching the nectariferous parenchyma, even close to the secretory epidermis. The histochemical tests revealed polysaccharides, mucilage and protein in the secretion, whereas the exudate chemical analysis showed that glucose, fructose and sucrose are components of the nectar, being fructose the sugar predominant. The secretion is complex and different organelles are involved in this synthesis and secretion process. Secretory parenchyma cells presented a large peripheral nucleus, vacuole with granular material, conspicuous endoplasmic reticulum, numerous mitochondria, plastids, and plasmodesmata. During the secretion process, a granular material is accumulated into the vacuole, which merges with the plasma membrane of the secretory epidermis, releasing this material into the periplasmatic spaces. After crossing the cell wall of the epidermal cell, the secretion is accumulated in a subcuticular space, until ready to be released by the cuticle disruption. Based on this study, we can affirm that the glands of it are extrafloral nectaries.

GINS2 Is Downregulated in Peripheral Blood of Patients with Intervertebral Disk Degeneration and Promotes Proliferation and Migration of Nucleus Pulposus Cells.

GINS complex subunit 2 (GINS2) regulates the migration, invasion, and growth of cells in many malignant and chronic diseases. In the present study, we aimed to investigate the expression of GINS2 in the peripheral blood and nucleus pulposus (NP) cells of patients with intervertebral disk degeneration (IDD). GINS2 expression was detected using bioinformatics tools from the GEO public repository and validated using peripheral blood samples from IDD patients and healthy participants. GINS2 clinical significance was explored by the receiver operating curve (ROC) utilizing area under the curve (AUC). Moreover, the influences of GINS2 on cell viability, migration, and invasion were explored by MTT, wound healing, and transwell assays, whereas cell apoptosis was determined by flow cytometry. Expression levels of GINS2 in the peripheral blood were significantly lower in IDD patients than in healthy participants. Moreover, ROC obtained a significantly higher AUC of GINS2 in IDD patients. Further, overexpressed GINS2 increased the proliferation, migration, and invasion of NP cells while overexpressed GINS2 decreased the apoptotic property of cells compared to the NC plasmid and control groups. In conclusion, GINS2 might be a potential therapeutic target of IDD.

Titanium dioxide nanoparticles promote histopathological and genotoxic effects in Danio rerio after acute and chronic exposures

Titanium dioxide nanoparticles (TiO2-NPs) are among the most used nanomaterials worldwide, but studies evaluating its genotoxicity and histopathological effects are scarce, dealing with short exposure times and low concentrations for human use. The aim was to evaluate TiO2-NPs genotoxicity and histological alterations in the intestine and liver of zebrafish after exposure to human consumption compatible concentrations. Fishes were acutely (96 hours) and chronically (30 days) exposed to 5.0, 20 and 40 mg L-1 of TiO2-NPs and later euthanized for organ and blood analysis through histological procedures and the micronucleus test, respectively. An increase in the thickness of intestinal villi was observed after acute and chronic exposure in the higher concentrations. The liver showed an increase in vacuolated hepatocytes after both exposures, besides an increase in hepatocytes with peripheral nucleus. Genotoxicity was only observed after chronic exposure, demonstrated by the increase in micronucleus and cell buddings. These findings indicate that TiO2-NPs cause histopathological damage even in acute exposures, as the intestine serves as a barrier for NPs and the liver is an organ that accumulates Ti. Genotoxicity was possibly mediated by reactive oxygen species through chronic inflammation, leading to tissue damage and carcinogenesis in longer exposures that represents human exposure time.

Analysis of kinetic freeze-out temperature and transverse flow velocity in nucleus–nucleus and proton–proton collisions at same center-of-mass energy

Transverse momentum spectra of different types of identified charged particles in central Gold–Gold (Au–Au) collisions and inelastic (INEL) or nonsingle diffractive (NSD) proton–proton (pp) collisions at the Relativistic Heavy Ion Collider (RHIC), as well as in central and peripheral Lead–Lead (Pb–Pb) collisions, and INEL or NSD pp collisions at the Large Hadron Collider (LHC) are analyzed by the blast-wave model with Tsallis statistics. The model results are approximately in agreement with the experimental data measured by STAR, PHENIX and ALICE Collaborations in special transverse momentum ranges. Kinetic freeze-out (KFO) temperature and transverse flow velocity are extracted from the transverse momentum spectra of the particles. It is shown that KFO temperature of the emission source depends on mass of the particles, which reveals the mass-dependent KFO scenario in collisions at RHIC and LHC. Furthermore, the KFO temperature and transverse flow velocity in central nucleus–nucleus (AA) collisions are larger than in peripheral collisions, and both of them are slightly larger in peripheral nucleus–nucleus collisions or almost equivalent to that in proton–proton collisions at the same center-of-mass energy which shows their similar thermodynamic nature.

Effect of different inducing hormones, sex ratio and oocyte diameter on breeding performance of brackish water catfish, Mystus gulio

Brackishwater catfish, Mystus gulio, is a commercially important fish of Southeast Asia. Farming of this fish is hindered due to unavailability of hatchery-produced seeds. In this study, three different experiments were conducted to determine suitable inducing hormone, operational sex ratio (OSR), and oocyte diameter for induced breeding of M gulio. In experiment one, human chorionic gonadotropin, HCG (5, 10, 15, 20 and 25 IU g−1), luteinizing hormone-releasing hormone analogue, LHRHa (2.5, 5, 7.5, 10 and 15 μg g−1) and commercial hormone, CH (a combination of LHRHa and domperidone) (10, 20, 25, 30 and 40 μl g−1) were tested separately. In experiment two, male and female-biased sex ratios, such as 1 M: 1F, 1 M: 2F, 1 M: 3F, 3 M: 1F, 2 M: 1F were used to ascertain correct OSR. Experiment three was conducted with four different size groups of oocytes (750–800, 801–850, 851–900, and 901–950 μm), and administration of primary and secondary doses of HCG (10 IU g−1 body weight) at 24 h interval. All the experimental treatments were conducted in triplicates (n = 3). Half the hormone dose of female was given to male in all the experiments. Result revealed that the effective doses of HCG, LHRHa and CH were 10 IU g−1, 5 μg g−1 and 20 μl g−1, respectively. Further, male biased sex ratio of 2 M: 1F caused significantly (p < 0.05) higher relative fecundity (169 eggs spawned g−1 fish), fertilization rate (77.33%), hatching rate (71.00%) and larval survival (31.67%). Female with minimum oocyte diameter of 851 to 950 μm, characterized by the presence of peripheral nucleus, is ideal for induced spawning. Oocyte with a further smaller diameter size of 801–850 μm required both primary and secondary doses of hormone injection. It is more economical to use CH for mass production of healthy larvae.

Representações sociais dos/as professores/as acerca da violência contra mulher: uma análise estrutural

O presente estudo se propõe a identificar as representações sociais da violência contra as mulheres entre professores/as da rede pública em cidades no sertão de Pernambuco. Participaram da pesquisa 60 profissionais dos três níveis da educação básica: educação infantil, ensino fundamental e médio. Para coleta de dados, foi aplicado um questionário de evocação livre e hierarquização de palavras, e as informações foram posteriormente organizadas em um quadro de quatro casas, que permite inferir o núcleo central e o sistema periférico de uma representação social. Os resultados mostraram que entre as palavras que compõem o núcleo central estão crime, crueldade, machismo e medo, que evidenciam o caráter normativo da representação, baseada na ideia da violência como uma construção sociocultural. O termo educação presente na segunda periferia aponta a importância da escola como agente de socialização na formação dos/as alunos/as. Conclui-se que os/as professores/as devem ser capacitados/as para fazer parte da rede de enfrentamento, compreendendo que a violência contra as mulheres é uma questão pertinente para o currículo escolar.

Polioencephalomalacia in Newborn Lamb

Background: Perinatal mortality in sheep is determined by death between 60 days of gestation and 28 days postpartum. The starvation / hypothermia complex was characterized by lambs that walked, but did not feed. Polioencephalomalacia (PEM) is a descriptive term that indicates the morphological diagnosis for necrosis with softening of the gray matter in the brain. There are no data available in the literature relating PEM to the starvation / hypoglycemia / hypothermia complex in small ruminants. Thus, the objective of this work is to report a case of polyioencephalomalacia related to the starvation / hypoglycemia / hypothermia and septicemia complex in a newborn sheep.Case: A 5-day-old sheep mixed race (Dorper x Santa Inês), female, 3.0 kg, from a rural property in the Federal District, was sent to the Veterinary Pathology Laboratory of the University of Brasilia, for a necropsy. Organ fragments were collected and fixed in a 10 % buffered formalin solution, routinely processed for histology and stained with Hematoxylin and Eosin (HE). Additionally, swabs from the meninges, eyeballs and navels were collected for bacteriology. The animal came from twin pregnancies and was weak since birth. With three days of life, it presented apathy, weakness, difficulty in breastfeeding, difficulty in walking, and decubitus in a self-auscultation position. After two days of evolution the lamb died. Macroscopically, eyeball opacity, omphalophlebitis and congested brain were observed. Microscopically in the frontal cortex, the leptomeninge was markedly thickened by a large number of neutrophils and, to a lesser extent, macrophages, lymphocytes and plasmocytes, associated with aggregates of free eosinophilic rods or in the cytoplasm of macrophages. In the underlying gray substance, the neurópilo was observed containing moderate amount of perineuronal vacuoles and distension of the perivascular space (perineuronal and perivascular edema), in addition to a large number of neurons with retracted and hypereosinophilic cytoplasm with the pycnotic and peripheral nucleus (neuronal necrosis). Moderate endothelial and astrocyte swelling was also observed. In the eyeball, they were seen in the anterior, posterior and vitreous chambers extending to the ciliary body, infiltrated by neutrophils, lymphocytes, plasmocytes and macrophages with a moderate amount of fibrin, which extended to the optic nerve papilla. In the vitreous chamber, a large number of free eosinophilic rods were found in the infiltrate and inside macrophages. The bulbar conjunctiva, the corneal limbus and the iridocorneal angle were slightly thickened by similar infiltrates. In the bacteriological examination of meninges, eyeballs and navels, pure Escherichia coli culture was isolated.Discussion: The diagnosis of PEM associated with meningitis and panuveitis in this study was based on clinical-pathological and microbiological findings. In small ruminants twin pregnancies occur more frequently, and it is common for puppies to be born weaker and not ingest colostrum properly, leading to a condition called failure in passive immunity transfer and thus developing some type of disease. Metabolic disorders that interfere with glycolysis and ATP production for neurons are among the causes of PEM, however there is little data in the literature relating PEM to the starvation / hypoglycemia / hypothermia complex. Another important factor related to inadequate colostrum intake and management is umbilical infections. Meningitis results from a septicemic manifestation of primary infection such as omphalophlebitis. The association of clinical and pathological data allowed the diagnosis of PEM associated with meningitis, which was confirmed by the isolation of Escherichia coli in pure culture.

El abuso sexual infantil en el entramado de las representaciones sociales del ser niña

El artículo presenta una investigación sobre las representaciones sociales del ser niña en los municipios de Chitaraque y Aquitania del departamento de Boyacá, como elemento comprensivo del abuso sexual infantil que afecta las niñas en esta región. La investigación cualitativa utilizó los grupos de discusión para la identificación del núcleo central y periférico de la representación, sustentada en el paradigma interpretativo fenomenológico. Los contenidos identificados destacan la interrelación entre edad y género como predisponentes en la sistematicidad de las violencias contra las niñas y de diferentes formas de vulneración y negación de la infancia en razón a la acción adultocéntrica patriarcal.

A Simple, Novel Approach to Capsulorhexis Formation in the Setting of A Mature Cataract and Miotic Pupil.

PurposeTo report a simple, effective technique for surgeons creating a capsulorhexis in patients with pupillary miosis and a dense, mature cataract.MethodsA single center, two-year retrospective chart review examined 1408 phacoemulsification cataract surgeries. The criteria for inclusion involved a dense, mature cataract and a pupil that was unresponsive to pharmacologic dilation preoperatively. A standardized technique was used for all cases consisting of a 1mm corneal paracentesis and 2.4mm temporal clear corneal incision. Synecholysis was performed if present, followed by the insertion of a 6.25mm malyugin ring under cohesive viscoelastic. The cohesive viscoelastic was removed via the irrigation aspiration tip. The paracentesis was sealed with a small amount of viscoelastic and an air bubble was placed in the anterior chamber. The anterior capsule was then painted with trypan blue. The air bubble and trypan blue were then replaced by a dispersive viscoelastic. Curvolinear capsulorrhexis was performed followed by standard phacoemulsion.ResultsNine patients ranging from 76 ± 12 years (mean ± standard deviation) met the criteria with a 4+ NS (n=5), white mature (n=3), or deep brunescent (n=1) cataract and 3mm pupil preoperatively. Pupillary miosis was caused by posterior synechia in 44.5% of the cases followed by pharmacologic interactions from tamsulosin and donepezil in 22.25% of cases respectively. One case involved idiopathic miosis likely from aging. Capsulorhexis formation was successful in all cases with no capsular tear, vitreous loss, or conversion to extracapsular cataract extraction (ECCE). However, one case had cortex retention requiring a second procedure for removal.ConclusionDense, mature cataracts and small pupils both compromise the view for the surgeon and may be significant risk factors for training ophthalmologists. Thus, good visualization of the anterior capsule and peripheral nucleus with our simple technique facilitates a reliable capsulorhexis, potentially limiting the risk of complications for ophthalmic surgeons.

Flow in AA and pA as an interplay of fluid-like and non-fluid like excitations

To study the microscopic structure of quark–gluon plasma, data from hadronic collisions must be confronted with models that go beyond fluid dynamics. Here, we study a simple kinetic theory model that encompasses fluid dynamics but contains also particle-like excitations in a boost invariant setting with no symmetries in the transverse plane and with large initial momentum asymmetries. We determine the relative weight of fluid dynamical and particle like excitations as a function of system size and energy density by comparing kinetic transport to results from the 0th, 1st and 2nd order gradient expansion of viscous fluid dynamics. We then confront this kinetic theory with data on azimuthal flow coefficients over a wide centrality range in PbPb collisions at the LHC, in AuAu collisions at RHIC, and in pPb collisions at the LHC. Evidence is presented that non-hydrodynamic excitations make the dominant contribution to collective flow signals in pPb collisions at the LHC and contribute significantly to flow in peripheral nucleus–nucleus collisions, while fluid-like excitations dominate collectivity in central nucleus–nucleus collisions at collider energies.

Formation Factors of Cytogenetic Violation of Rutilus rutilus (Cypriniformes, Cyprinidae) in Transformed River Ecosystems

Abstract For the first time, an analysis of structural damage of the peripheral blood erythrocyte nucleus in Rutilus rutilus (Linnaeus, 1758) was carried out for the rivers of the north-western region of Ukraine. The effect of the hydrochemical regime on the formation of cytogenetic disturbances of the representatives of this species was also clarified. It was observed that during 2013–2017, the content of phosphates, suspended solids, fluorides, iron, copper, zinc, manganese, nitrite nitrogen and nitrate nitrogen in the surface waters of rivers most significantly exceeded the current quality standards. The average frequency of nuclear disorders of peripheral blood erythrocytes R. rutilus from the studied hydrosystems is 5.25 ± 0.29 ‰ (p &lt; 0.01), with a noticeable excess of the level of spontaneous mutations in the older age groups of fish. In all analyzed samples of R. rutilus, among the total number of identified structural disorders of the nucleus, the largest share is made up of red blood cells from the micronucleus (from 40.0 to 62.0 %), which is evidence of cytogenetic disturbances in the body of fish. At the same time, disturbances of erythrocyte blood of roach from small rivers are on average 1.3 times (or 21.9 %) higher compared with individuals from medium-sized rivers. The formation of cytogenetic disturbances in R. rutilus under the conditions of the hydrochemical regime of rivers is described by a close (r = 0.99 at p &lt; 0.003) multifactorial regression dependence. More important regressive coefficients of the dependency are acquired by such biogenes (NH4+, NO3−, PO4−) and toxicants (Cu2+, Zu2+, Mn2+, F2) in the background of oxygen regime peculiarities (COD, BOD5, O2).

The Spermatozoal Ultrastructure of the Chinese Mitten Crab (Eriocheir sinensis).

Background:The Chinese mitten crab (Eriocheir sinensis) is an economically important aquatic species in China. The artificial breeding crabs are also increasing in number day by day. However, knowledge about spermatozoal organization of the crab is still very limited.Aims and Objectives:In the present study, the spermatozoal ultrastructure of the E. sinensis is illustrated for improving artificial breeding technique.Materials and Methods:The spermatozoa are observed by light microscopy and transmission electron microscopy.Results:Spermatozoa are located in the lumen of seminiferous tubules. The spermatocytes and spermatids are observed in the wall of seminiferous tubules. The spermatophores are both present in the lumen of vas deferens and seminal vesicles. A mature spermatozoon consists of a central electron dense acrosome and a peripheral electron lucent nucleus within structures-organelles complex. The acrosome is divided into three zones, including inner acrosome zone, outer acrosome zone and zonal texture. The centre of acrosome is the perforatorium within parallel arranged perforatorial tubules along vertical axis. The highest electron dense operculum surrounds the head side of perforatorium.Conclusion:The ultrastructure of spermatozoa of E. sinensis is illustrated. In particular, the outermost part of the acrosome appears as concentric circles and is described as zonal texture.

No genetic differentiation, but less diversity, in the Iberian breeding population of the Eurasian Curlew (Numenius arquata)

The Iberian Peninsula harbours an “Endangered” population of the Eurasian Curlew (Numenius arquata), of less than five breeding pairs, restricted to a small geographical area, the Terra Cha district in Lugo (Galicia, Spain). These birds constitute the southernmost breeding nuclei of the species, located 550 km southwest from the nearest nesting sites in France. The present study aims to shed light on the genetic pattern of this population, and quantify the current levels of genetic diversity. We sequenced one mitochondrial gene and two nuclear introns of Eurasian Curlew sampled during the breeding season in Spain, Germany, Sweden and the Russian Federation. Overall, we observed low genetic variation among loci, including a monomorphic intron. Neither mitochondrial DNA (mtDNA) nor nuclear DNA (nDNA) showed differentiation between the Iberian population and the European Curlew (Numenius arquata arquata). The Iberian birds share a single mtDNA haplotype, which is the most common among populations, and the four nDNA haplotypes present in the Iberian birds are shared with other populations, including that of the farmost Siberian Curlew (Numenius arquata orientalis). We could not reject the hypothesis of a recent colonization of the Iberian Peninsula by the European Curlew, but the lack of variation in the Iberian gene pool during the last decade suggests no current recruitment from other populations, which might impair the persistence of this peripheral breeding nucleus.

Absence of jet quenching in peripheral nucleus–nucleus collisions

Medium effects on the production of high-pT particles in nucleus–nucleus (AA) collisions are generally quantified by the nuclear modification factor (RAA), defined to be unity in absence of nuclear effects. Modeling particle production including a nucleon–nucleon impact parameter dependence, we demonstrate that RAA at midrapidity in peripheral AA collisions can be significantly affected by event selection and geometry biases. Even without jet quenching and shadowing, these biases cause an apparent suppression for RAA in peripheral collisions, and are relevant for all types of hard probes and all collision energies. Our studies indicate that calculations of jet quenching in peripheral AA collisions should account for the biases, or else they will overestimate the relevance of parton energy loss. Similarly, expectations of parton energy loss in light–heavy collision systems based on comparison with apparent suppression seen in peripheral RAA should be revised. Our interpretation of the peripheral RAA data would unify observations for lighter collision systems or lower energies where significant values of elliptic flow are observed despite the absence of strong jet quenching.

Chronic liver disease in cattle associated with ingestion of Brachiaria spp.

ABSTRACT: One hundred and ninety livers condemned due to chronic disease (fibrosis) were evaluated in a bovine slaughterhouse over 12 months. Hepatic lymph nodes were also examined while still attached to livers. The major macroscopic lesion observed in the livers was moderate to severe atrophy of the left lobe associated with compensatory hypertrophy of the right lobe. Histologically, the main changes corresponded to sites of macroscopic lesions, and fibrosis was observed in all livers, along with bile duct hyperplasia and neovascularization. Masson's trichrome stain highlighted the fibrous connective tissue. Most of the livers analyzed had macrophages with foamy cytoplasm and a peripheral nucleus that infiltrated fibrotic areas. Immunohistochemistry (IHC) for macrophages with monoclonal antibody clone MAC 387 revealed that the cytoplasm of the foamy macrophages of the liver and of the hepatic lymph nodes were positively immunostained. These cells are frequently associated to the consumption of grasses of the genus Brachiaria. Although the liver gross lesions described in this study have not been previously reported in animals consuming Brachiaria , the associated changes observed histologically, such as fibrosis and infiltration of foamy macrophages, showed a new form of chronic liver disease probably associated with the consumption of this forage. The IHC technique was important to prove that the foam cells observed are macrophages.

Heróis e cultura histórica entre estudantes no Chile

RESUMO Este texto divulga e analisa dados do projeto intercultural de pesquisa "Jovens e a História no Mercosul". Expõe dados sobre a cultura histórica do Chile, especificamente sobre as imagens que personificam a identidade nacional, por meio dos líderes da pátria, com base na visão de estudantes do Ensino Médio. O fundamento teórico do estudo está nos conceitos de cultura histórica, cultura política e representações sociais, especificamente a teoria do núcleo central. Os dados foram coletados por meio de um questionário e tratados pelo programa EVOC 2000. Os resultados apontam, entre outras conclusões provisórias, um núcleo central que envolve O'Higgins, Prat e Carrera. Manuel Rodríguez e Salvador Allende são nomes do núcleo intermediário. O núcleo periférico é marcado por manifestações que modificam o significado de herói, apresentam irreverência ou destacam os nomes de Lautaro e Violeta Parra.

Centrality and system-size dependencies of temperatures of soft and hard components ofptdistributions of negative pions inHe4+C12,C12+C12, andC12+Ta181collisions atsNN=3.14GeV

Collision centrality as well as the system-size dependencies of the temperatures of the soft (${p}_{t}=0.1\ensuremath{-}0.5\phantom{\rule{4.pt}{0ex}}\text{GeV}/c$) and hard (${p}_{t}=0.5\ensuremath{-}1.2\phantom{\rule{4.pt}{0ex}}\text{GeV}/c$) components of the experimental transverse momentum distributions of the negative pions produced in $^{4}\mathrm{He}{+}^{12}\mathrm{C}, ^{12}\mathrm{C}{+}^{12}\mathrm{C}$, and $^{12}\mathrm{C}{+}^{181}\mathrm{Ta}$ collisions at $4.2A\phantom{\rule{4.pt}{0ex}}\text{GeV}/c$ ($\sqrt{{s}_{NN}}=3.14\phantom{\rule{0.16em}{0ex}}\mathrm{GeV}$) are analyzed. For the studied collision systems and selected collision centralities, the temperatures are extracted from fitting separately the soft and hard ${p}_{t}$ components of the negative pions by one-temperature Hagedorn and one-temperature Boltzmann functions. The extracted temperatures of both the soft and hard components of the ${p}_{t}$ distributions of ${\ensuremath{\pi}}^{\ensuremath{-}}$ depend on the geometry (size) and degree of overlap of the colliding nuclei in peripheral, semicentral, and central nucleus--nucleus collisions at $\sqrt{{s}_{NN}}=3.14\phantom{\rule{0.16em}{0ex}}\mathrm{GeV}$. The gap (differences) between the extracted temperatures in the studied collision systems increases with increasing the degree of overlap of the colliding nuclei, i.e., with an increase in the collision centrality and the corresponding increase in the numbers of participant nucleons and binary collisions. The temperature of the soft ${p}_{t}$ component of the negative pions in $^{12}\mathrm{C}{+}^{12}\mathrm{C}$ ($^{12}\mathrm{C}{+}^{181}\mathrm{Ta}$) collisions increases (decreases) with increasing of the collision centrality. The temperature of the hard ${p}_{t}$ component of ${\ensuremath{\pi}}^{\ensuremath{-}}$ in $^{12}\mathrm{C}{+}^{181}\mathrm{Ta}$ ($^{4}\mathrm{He}{+}^{12}\mathrm{C}$) collisions increases (decreases) consistently with an increase in the collision centrality. The temperature of the soft ${p}_{t}$ component of ${\ensuremath{\pi}}^{\ensuremath{-}}$ decreases with an increase in the system size in semicentral and central nucleus--nucleus collisions at $\sqrt{{s}_{NN}}=3.14\phantom{\rule{0.16em}{0ex}}\mathrm{GeV}$. In central collisions, the temperature of the hard ${p}_{t}$ component increases consistently with an increase in system size. The physical interpretations of the results obtained are given. The quantitative results on temperatures extracted from the ${p}_{t}$ spectra of negative pions in nucleus--nucleus collisions at $4.2A\phantom{\rule{4.pt}{0ex}}\text{GeV}/c$ are compared to those obtained in lower, intermediate, and higher energies in other Joint Institute for Nuclear Research (JINR), Gesellschaft f\"ur Schwerionenforschung (GSI), and SPS experiments.

Surgical correction of lens luxation in the horse: visual outcomes

Introduction The lens is an avascular transparent biconvex sphere whose primary purpose is to refract and focus light rays onto the retinal photoreceptors [1-4]. It consists of cellular lens fibers with a peripheral cortex and central nucleus surrounded by an elastic capsule [2]. Transparent zonular ligaments arise on and between the