Eccentricity samples: implications on the potential and the velocity distribution

Planar and vertical epicycle frequencies and local angular velocity are related to the derivatives up to the second order of the local potential and can be used to test the shape of the potential from stellar disc samples. These samples show a more complex velocity distribution than halo stars and should provide a more realistic test. We assume an axisymmetric potential allowing a mixture of independent ellipsoidal velocity distributions, of separable or Staeckel form in cylindrical or spherical coordinates. We prove that values of local constants are not consistent with a potential separable in addition in cylindrical coordinates and with a spherically symmetric potential. The simplest potential that fits the local constants is used to show that the harmonical and non-harmonical terms of the potential are equally important. The same analysis is used to estimate the local constants. Two families of nested subsamples selected for decreasing planar and vertical eccentricities are used to borne out the relation between the mean squared planar and vertical eccentricities and the velocity dispersions of the subsamples. According to the first-order epicycle model, the radial and vertical velocity components provide accurate information on the planar and vertical epicycle frequencies. However, it is impossible to account for the asymmetric drift which introduces a systematic bias in estimation of the third constant. Under a more general model, when the asymmetric drift is taken into account, the rotation velocity dispersions together with their asymmetric drift provide the correct fit for the local angular velocity. The consistency of the results shows that this new method based on the distribution of eccentricities is worth using for kinematic stellar samples.Peer ReviewedPostprint (author's final draft

Orbital eccentricities as indicators of stellar populations: a kinematical analysis of the local disc from GAIA DR2 catalogue

Aims. Based on a local sample from Gaia DR2 catalogue composed of 74 339 stars, we are able to derive more accurate kinematic statistics defining the local stellar populations and classify the stars in terms of their planar and vertical orbital eccentricities. Methods. Firstly, we carried out a kinematical characterisation of stellar populations from a tested mixture model that fits the trivariate velocity cumulants up to the fourth order, maximises the entropy of the mixture probability, and minimises the ¿2 error. We then proposed several approaches to classifying the stars according to the population they are most likely to belong to. None of these approaches provided a definitive solution due to the overlapping of the partial distributions. Finally, by using the epicycle approximation, we transformed the three-dimensional velocity probability space into a two-dimensional diagram. In one direction, the information of the two planar velocity components is picked up by the planar eccentricity. In the other direction, the vertical eccentricity does the same with the vertical velocity component. However, in the vertical direction, the epicycle approximation is not valid and it is replaced by a biquadratic approximation. Results. In the eccentricity diagram, the region of maximum probability for a population is approximately delimited by straight line. We characterise three local kinematic populations: thin disc, thick disc (composed of two subpopulations: canonical thick disc and metal-weak thick disc), and kinematical halo (metal-rich thick-disc plus chemical halo). The Gaia DR2 sample allows us to estimate small mean radial differential motion of 5 ± 2 km s-1 between the thin and thick discs, and of 9 ± 3 km s-1 between both thick-disc subpopulations, as well as between the disc and the kinematical halo. All disc populations and subpopulations have significant vertex deviations. Conclusions. The classification of the stars from the eccentricity diagram resolves the problem of overlapping velocity distributions by producing a segregation that is more net, along with a more precise kinematical characterisation of populations.Peer ReviewedPostprint (author's final draft

Orbital eccentricities as indicators of stellar populations. II. Vertical velocity distribution from the Gaia DR2 catalogue

Context. In previous work, we showed how the planar and vertical eccentricities of disc stars, e and e' , could be used as indicators of the stars’ kinematic populations. For a local stellar sample drawn from the Gaia DR2 catalogue, these populations were represented geometrically in the eccentricity diagram, e'² vs e² , approximately separated by straight lines. Aims. In the current work, we propose a new relationship between the star’s perpendicular velocity and its vertical eccentricity, allowing for a reevaluation of the critical vertical eccentricity and maximum height, z_max, specific to each population component. Methods. We approximated the local potential function to be consistent with the actual shape of the curve that relates the maximum vertical speed of a star and its maximum height. The curve corresponds to a non-linear restoring vertical force, where the stiffness decreases with an increase in the maximum height. The constants involved in this fitting, together with the population velocity dispersions, determine the specific region for each population in the eccentricity diagram. Results. The new classification determines 88% of the sample is made up of thin disc stars and 9% of thick disc stars, whereby 3% of the stars have been relabelled, by providing thinner thin and thick discs. Nested thin disc subsamples allow us to estimate Strömberg’s asymmetric drift equation, leading to a heliocentric velocity of the circular orbit of V_c ˜ -12.9 km s -1 , an absolute rotation velocity of T_c ˜ 227 km s -1 , and a rotation component of the Galactocentric velocity of the Sun at T_¿ ˜ 240 km s -1 . Conclusions. The thin disc stars of our local sample are characterised based on values 0 = e = 0.32, 0 = e' = 0.09, and z_max = 0.7 kpc. Disc stars satisfy 0 = e = 0.44, 0 = e' = 0.18, z_max = 1.5 kpc. The maximum vertical peculiar velocity for disc stars is found to be w_0 = 115 km s -1 . The assumed potential provides a stellar density of the disc vanishing at z_0 = 1.8 kpc. The approximate behaviour in the local disc is that a small decrease in the stiffness is associated with a relative decrease in the limiting velocity, which produces a thinner disc and a loss of stars in the local cylinder, both in a similar proportion to the limiting velocity.Peer ReviewedPostprint (author's final draft

Histological and Morphometric Examination of the Testes of Boars and Male Pigs Immunocastrated with Improvac®

Background: Surgical castration of male piglets is frequently performed to prevent development of an unpleasant taste and flavor in meat of mature males, called boar taint. Disadvantages of this method are primarily related to the lower feed efficiency of surgically castrated male pigs, production of less lean meat and more fat on the carcasses than boars, as well as ethical issues associated with the procedure itself. Immunocastration is a method of immunization against gonadotropinreleasing hormone (GnRH) and represents an alternative to avoid boar taint. This study aimed to examine the influence of immunocastration on histological and morphometric parameters of male pig testes.Materials, Methods & Results: A total of 60 crossbred male pigs selected from 30 litters were assigned to two experimental groups: boars (n = 30) and immunocastrated males (n = 30). Two doses (2 mL per dose) of the Improvac® vaccine were given to pigs scheduled for immunocastration. The first injection was given at 10 weeks of age, and the second injection at 20 weeks of age. All pigs were fed the same commercial diet ad libitum, group-housed (15 pigs/pen) and slaughtered at 25 weeks of age. After slaughter, testicle weights were measured and samples of testicular tissue were taken for histological examination. Immunocastrated males had lower testicle weights than boars (P < 0.01). Furthermore, structural damage to the germinal epithelium was visible in the seminiferous tubules of vaccinated pigs. In the testicular interstitium of these animals, the number of Leydig cells were reduced; almost all of these cells exhibited different degrees of abnormality. Moreover, the diameter of the seminiferous tubules and thickness of the germinal epithelium were greater (P < 0.01), and the percentage of germinal epithelium in the seminiferous tubules as well as percentage of blood vessels in the interstitium were higher in boars as compared to immunocastrated males (P < 0.01). Seminiferous tubule lumen diameter was greater (P < 0.01), and percentage of lumen in the seminiferous tubules as well as percentage of non-blood vessel tissue in the interstitium were higher in immunocastrated males than boars (P < 0.01).Discussion: Vaccination against GnRH, as used in this study, reduced the synthesis of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which led to decreased spermatogenesis and androgen production. The smaller diameter of the seminiferous tubules as well as germinal epithelium thickness, and lower percentage of germinal epithelium in the seminiferous tubules in immunocastrated males could be explained by reduced FSH synthesis, and subsequent reduced spermatogenesis. The described testicular malformations in immunocastrated animals caused their lower weight, and greater diameter of the lumen as well as a higher lumen percentage of the seminiferous tubules. The vaccine reduced LH synthesis, so the Leydig cells of immunocastrated animals had lower activity than the same cells in boars. The percentage of blood vessels in the interstitium of boar testes was higher, which was related to the blood supply required for normal function of Leydig cells. It was concluded that differences existed in the structure of the seminiferous tubules and interstitium between boars and immunocastrated males , which were reflected in values of the examined histological and morphometric parameters. The development of these differences was related to the inhibition of GnRH synthesis and secretion

Effects of Acute Administration of D,L-Homocysteine Thiolactone on the Antioxidative Status of Rat Intestine and Liver

Oxidative stress appears to play a role in the pathogenesis of several inflammatory gastrointestinal diseases. Increased homocysteine levels may play a role in the pathogenesis of Chrons disease and ulcerative colitis. The aim of this study was to examine the influence of homocysteine on the antioxidant status of rat intestine and liver. The levels of thiobarbituric acid reactive substances (TBARS), activity of catalase (CAT) and total antioxidant status (TAS) were investigated in the isolated gut and liver of young male rats in the control group (8 rats) and after 3-hour incubation in high doses of D, L-homocysteine thionolactone (Hcy) (10 mu mol/L) (8 rats). Samples of duodenum, ileum, colon and liver were homogenized in sodium phosphate buffer (1: 10). Homogenates were centrifuged at 10000 for 10 min at 4 degrees C and the supernatant was taken for biochemical assays. Our results showed that high D, L-homocysteine thionolactone concentration reduced enzymatic catalase activity in homogenates of the isolated segments of duodenum (27.04%) p LT 0.01; ileum (37.27%), colon (34.17%) and liver (67.46%) p LT 0.001. Exposition to high D, L-homocysteine thiolactone concentration significantly increased TBARS levels in the duodenum (106.05%), ileum (47.24%), colon (112.75%) and liver (32.07%) (p LT 0.01). Homocysteine also modified the total antioxidant status of homogenates from the duodenum, ileum, colon and liver, increasing by 20.68% (duodenum), 24.74% (ileum), 14.88% (colon) and 19.35% (liver) (p LT 0.001). Homocysteine induced a consistent oxidative stress in rats intestine and liver (reduced activity of catalase and increased level of TBARS), but the elevated activity of TAS in our experiments could be explained as an adaptive response to the generated free radicals which indicates the failure of the total antioxidant defense mechanism to protect the tissues from damage caused by homocysteine

Multiple myeloma invasion of the central nervous system

Introduction. Multiple myeloma (MM) is characterized by the presence of neoplastic proliferating plasma cells. The tumor is generally restricted to the bone marrow. The most common complications include renal insufficiency, hypercalcemia, anemia and reccurent infections. The spectrum of MM neurological complications is diverse, however, involvement of MM in the cerebrospinal fluid (CSF) and leptomeningeal infiltration are rare considered. In about 1% of the cases, the disease affects the central nervous system (CNS) and presents itself in the form of localized intraparenchymal lesions, solitary cerebral plasmocytoma or CNS myelomatosis (LMM). Case report. We presented the clinical course of a 55-year-old man with MM and LMM proven by malignant plasma cells in the CSF, hospitalized with the pain in the thoracic spine. His medical history was uneventful. There had been no evidence of mental or neurological impairment prior to the seizures. Physical examination showed no abnormalities. After a complete staging, the diagnosis of MM type biclonal gammopathia IgG lambda and free lambda light chains in the stage III was confirmed. The treatment started with systemic chemotherapy (with vincristine, doxorubicin plus high-dose dexamethasone - VAD protocol), radiotherapy and bisphosphonate. The patient developed weakness, nausea, febrility, dispnea, bilateral bronchopneumonia, acute renal insufficiency, confusions, headaches and soon thereafter sensomotor aphasias and right hemiparesis. The patient was treated with the adequate therapy including one hemodyalisis. His neurological status was deteriorated, so Multislice Computed Tomography (MSCT) of the head was performed and the findings were normal. Analysis of CSF showed pleocytosis, 26 elements/ mL and increased concentrations of proteins. Cytological analysis revealed an increased number of plasma cells (29%). Electrophoretic analysis of proteins disclosed the existance of monoclonal components in the serum, urine and CSF. Immunofixation electrophoretic and quantitative nephelometric tests confirmed Biclonal multiple myeloma of IgG lambda and light chain lambda isotypes. Analysis of neurothropic viruses with ELISA methods was negative. Once the presence of LMM was confirmed, the patient received intrathecal chemotherapy with methotrexate, cytosine arabinoside, dexamethasone three times a week, and systemic high doses of dexamethasone iv like a single agent without craniospinale irradiations. Despite the treatment, the patient died one month after the diagnosis. Autopsy was not performed. Conclusion. Presented patient, as well as most other patients with MM progressing to CNS infiltration was in the stage III. In addition to the detailed clinical examination, and all investigations required for MM diagnosis and staging of the disease, we introduced the additional CSF examination and calculation of kappa lambda ratio, that helped us make an early diagnosis and prognosis of MM with LMM. Although LMM had a low prevalence, it could be more frequent than expected especially in patients with high risk. CSF examination with positive plasma cells and abnormal morphology remains the hallmark for diagnosing CNS infiltration

Neonatal screening of hearing function by otoacustic emissions - a single center experience

Background/Aim. Nowadays development of techniques enables detection of hearing impairment in a very short time, immediately after birth by using otoacoustic emissions. They are low-pitched sounds produced in physiologically clear cochlea and can be recorded in cochlear outer meatus. By this method, complete data are found on a whole presynaptic auditory nervous system functioning that has mostly been affected by pathological changes making it a perfect screening test. Reliability and sensibility of this method is up to 98%. The aim of this study was to present the first results of systematic neonatal screening of hearing function by otoacoustic emissions in the Clinical Center Kragujevac (Kragujevac, Serbia). Methods. This prospective study of neonatal hearing screening function, initiated systematically by the 2008 at the Clinical Center Kragujevac, included full-term newborns and premature born ones, within the first 24 h after birth, using a DPOAEs interacoustics otoread-screener. Retesting was done after a month. Results. From January 1st, 2009 to December 1st, 2010, a total number of examined infants by this method was 1,994 out of which 1,778 were full-term and 216 were premature born. The test passing was higher in the group of full-term babies (92.5%) than in the preterm ones (55.1%). No bilateral answers were recorded in premature born children compared to the full-term ones, of whom a larger number was with missing lateral responses. The results of re-examination test in the group of full-term born and premature newborns were 83.7%, and 61%, respectively. Conclusion. Deliberately provoked transient otoacoustic emission is an efficient method in testing hearing function in newborns, since it is non-invasive, rapid and objective. Its correlation with audibly evoked potentials is very high, which confirms its reliability

Characterization and biological activity of exopolysaccharide extracted from novel probiotic strain L. reuteri B2., as novel biomaterial

Probiotics as the most promising group of microbes have the possibility to synthesize metabolites, that can be used in different industries over the world. In this study, we investigated the probiotic activity of the Lactobacillus reuteri B2, as well as, the exopolysaccharides (EPS) that this strain produced. L. reuteri B2 was isolated from the feces of C57BL/6 mice and assessed on probiotic activity. L. reuteri B2 was identified by 16S rDNA sequencing, in which the cell viability in acidic conditions at pH 2.0 was 64% after 2 h, and in the presents of 0.30% of the bile salts, after 6 h, was 37%. Antimicrobial assay with L. reuteri B2 showed maximum diameters against K. oxytoca J7 (12.5±0.71mm). We further hypothesized if L. reuteri B2 strain in the free form can survive all conditions in the gastrointestinal tract (GIT) then the utilization of the appropriate biomaterials would ameliorate its stability and viability in GIT. L. reuteri B2 was microencapsulated into sodium alginate- (Na-alg) and different content of Na-alg and sodium maleate (SM) beads. Second hypothesis was if a novel EPS, extracted and isolated from L. reuteri B2, that obtain biological activity can be used as biomaterial. Characterization of this EPS enveloped FTIR, NMR, SEM, XRD, TGA/DTG analysis, biological assays, antioxidative activity, cytotoxic assay (MTT), and adhesion assay of L. reuteri B2 to HT29 cells. This EPS obtained a high scavenging effect of 76% at 2mg/mL of EPS in ABTS assay, while in MTT assay showed that did not have a cytotoxic effect

Primena novih sorbenasa u D-µ-SPE TEhnici pripreme uzoraka za GC – MS analizu PAU u vodi

The aim of this paper is application of novel sorbents in dispersive micro solid phase extraction (D-μ-SPE) as a technique for sample preparation of water, for the analysis of 16 PAHs by gass chromatography - mass spectrometry (GC-MS). D-μ-SPE proved to be an effective technique consuming a small amount of the solvent for the analysis. D-μ-SPE is characterized by its rapidity (7 minutes per sample including all preparation of standard solutions and measuring of sorbents) and cheapness as well. Low values of the detection limit and limit of quantification, acceptable accuracy and precision values propose this method for routine water analysis for the determination of PAHs.Cilj istraživanja ovog rada je primena novih sorbenasa u disperzivnoj mikroekstrakciji čvrstom fazom (D-µ-SPE) kao tehnikom pripreme uzoraka vode za analizu 16 prioritetnih PAU gasnom hromatografijom sa masenom spektrometrijom (GC-MS). D-µ-SPE se pokazala kao efikasna i ekonomična tehnika pripreme uzoraka vode pri čemu se troši mala količina rastvarača za ekstrakciju i koristi jeftin pribor za pripremu uzoraka koja traje 7 minuta (uključujući pripreme standardnih rastvora i odmeravanje sorbenasa). Niske vrednosti granice detekcije i kvantifikacije, prihvatljive vrednosti tačnosti i preciznosti predloženu metodu analize 16 prioritetnih PAU kvalifikujuje za rutinsku analizu vode

Primena disperzivne mikroekstrakcije čvrstom fazom kao tehnike pripreme uzoraka za GC – MS analizu PAU u vodi

The aim of this paper is to determine the efficiency of D-µ-SPE with application of novel sorbents as a technique for sample preparation of water samples for the analysis of 16 priority PAHs by GC-MS. The sample preparation technique proved to be very fast, efficient and economical. The results of the proposed method demonstrate that this technique can be applied for routine analysis of PAHs in water. The advantages of this method are characterized by low values of limit of detection (from 0.147 ppb for benzo [a] anthracene to 0.784 ppb for naphthalene) and the limit of quantification (0.717 ppb for naphthalene to 9.459 ppb for benzo [k] fluorantene.Ciljevi istraživanja ovog rada su određivanje efikasnosti disperzivne mikroekstrakcije čvrstom fazom (D-µ-SPE) kao tehnike pripreme uzoraka vode za analizu 16 prioritetnih PAU gasnom hromatografijom sa masenom spektrometrijom, primenom novih sorbenasa. Tehnika pripreme uzoraka pokazala se kao veoma brza, efikasna i ekonomična. Rezultati predložene metode dokazuju da se ova tehnika može primeniti kao tehnika pripreme uzoraka za rutinsku analizu PAU u vodi. Prednosti ovakovog načina analize odlikuju se niskim vrednostima granice detekcije (od 0.147 ppb za benzo[a]antracen do 0.784 ppb za naftalen) i granice kvatifikacije (0.717 ppb za naftalen do 9.459 ppb za benzo[k]fluoranten)