142 research outputs found

    Heavy metal (Zn, Pb, Cd) concentration in soil and moss (Pleurozium schreberii) in the Brynica district, southern Poland

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    Determinants and coverage of seasonal influenza vaccination among women of childbearing age in Poland

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    Objectives: Vaccination is the most effective method of controlling influenza in the human population, where pregnant women belong to a risk group that is especially vulnerable to influenza-related morbidity and mortality. The objectives of the survey were to report estimates of maternal vaccination coverage and assess reasons for the lack of influenza vaccination among Polish women of childbearing age. Material and methods: The survey analysis included 564 pregnant women who had been surveyed in a self-reported questionnaire during the 2017–2018 influenza season in Warsaw, Poland. Results: Over 95% of Polish women of childbearing age did not vaccinate against influenza due to the low perception of risk and a lack of providing evidence-based information on vaccine by physicians and midwives. General practitioners were most often indicated as healthcare workers who educated women about influenza risk factors and recommended influenza vaccine to them. Conclusions: The results of the survey suggest that women of childbearing age did not vaccinate against influenza due to the low perception of risk and a lack of providing evidence-based information by healthcare workers (including obstetrician-gynaecologists and midwives), while their recommendations appear to be a powerful method of overcoming barriers to influenza vaccination among patients

    Optimization of broadband semiconductor chirped mirrors with genetic algorithm

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    Genetic algorithm was applied for optimization of dispersion properties in semiconductor Bragg reflectors for applications in femtosecond lasers. Broadband, large negative group-delay dispersion was achieved in the optimized design: The group-delay dispersion (GDD) as large as −3500 fs2 was theoretically obtained over a 10-nm bandwidth. The designed structure was manufactured and tested, providing GDD −3320 fs2 over a 7-nm bandwidth. The mirror performance was verified in semiconductor structures grown with molecular beam epitaxy. The mirror was tested in a passively mode-locked Yb:KYW laser

    Magnetospectroscopy of symmetric and anti-symmetric states in double quantum wells

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    The experimental results obtained for the magneto-transport in the InGaAs/InAlAs double quantum wells (DQW) structures of two different shapes of wells are reported. The beating-effect occurred in the Shubnikov-de Haas (SdH) oscillations was observed for both types of the structures at low temperatures in the parallel transport when magnetic field was perpendicular to the layers. An approach to the calculation of the Landau levels energies for DQW structures was developed and then applied to the analysis and interpretation of the experimental data related to the beating-effect. We also argue that in order to account for the observed magneto-transport phenomena (SdH and Integer Quantum Hall effect), one should introduce two different quasi-Fermi levels characterizing two electron sub-systems regarding symmetry properties of their states, symmetric and anti-symmetric ones which are not mixed by electron-electron interaction.Comment: 20 pages, 20 figure

    Parallel magnetotransport in multiple quantum well structures

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    The results of investigations of parallel magnetotransport in AlGaAs/GaAs and InGaAs/InAlAs/InP multiple quantum wells structures (MQW’s) are presented in this paper. The MQW’s were obtained by metalorganic vapour phase epitaxy with different shapes of QW, numbers of QW and levels of doping. The magnetotransport measurements were performed in wide region of temperatures (0.5–300 K) and at high magnetic fields up to 30 T (B is perpendicular and current is parallel to the plane of the QW). Three types of observed effects are analyzed: quantum Hall effect and Shubnikov—de Haas oscillations at low temperatures (0.5–6 K) as well as magnetophonon resonance at higher temperatures (77–300 K)

    Arabinogalactan-protein and pectin epitopes in relation to an extracellular matrix surface network and somatic embryogenesis and callogenesis in Trifolium nigrescens Viv

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    The formation of an extracellular matrix surface network (ECMSN), and associated changes in the distribution of arabinogalactan-protein and pectin epitopes, have been studied during somatic embryogenesis (SE) and callogenesis of Trifolium nigrescens Viv. Scanning electron microscopy observations revealed the occurrence of an ECMSN on the surface of cotyledonary-staged somatic embryos as well as on the peripheral, non-regenerating callus cells. The occurrence of six AGP (JIM4, JIM8, JIM13, JIM16, LM2, MAC207) and four pectin (JIM5, JIM7, LM5, LM6) epitopes was analysed during early stages of SE, in cotyledonary-staged somatic embryos and in non-embryogenic callus using monoclonal antibodies. The JIM5 low methyl-esterified homogalacturonan (HG) epitope localized to ECMSN on the callus surface but none of the epitopes studied were found to localize to ECMSN over mature somatic embryos. The LM2 AGP epitope was detected during the development of somatic embryos and was also observed in the cell walls of meristematic cells from which SE was initiated. The pectic epitopes JIM5, JIM7, LM5 and LM6 were temporally regulated during SE. The LM6 arabinan epitope, carried by side chains of rhamnogalacturonan-I (RG-I), was detected predominantly in cells of embryogenic swellings, whilst the LM5 galactan epitope of RG-I was uniformly distributed throughout the ground tissue of cotyledonary-staged embryoids but not detected at the early stages of SE. Differences in the distribution patterns of low and high methyl-esterified HG were detected: low ester HG (JIM5 epitope) was most abundant during the early steps of embryo formation and highly methyl-esterified form of HG (JIM7 epitope) became prevalent during embryoid maturation

    Ovaries of Tubificinae (Clitellata, Naididae) resemble ovary cords found in Hirudinea (Clitellata)

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    The ultrastructure of the ovaries and oogenesis was studied in three species of three genera of Tubificinae. The paired ovaries are small, conically shaped structures, connected to the intersegmental septum between segments X and XI by their narrow end. The ovaries are composed of syncytial cysts of germ cells interconnected by stable cytoplasmic bridges (ring canals) and surrounded by follicular cells. The architecture of the germ-line cysts is exactly the same as in all clitellate annelids studied to date, i.e. each cell in a cyst has only one ring canal connecting it to the central, anuclear cytoplasmic mass, the cytophore. The ovaries found in all of the species studied seem to be meroistic, i.e. the ultimate fate of germ cells within a cyst is different, and the majority of cells withdraw from meiosis and become nurse cells; the rest continue meiosis, gather macromolecules, cell organelles and storage material, and become oocytes. The ovaries are polarized; their narrow end contains mitotically dividing oogonia and germ cells entering the meiosis prophase; whereas within the middle and basal parts, nurse cells, a prominent cytophore and growing oocytes occur. During late previtellogenesis/early vitellogenesis, the oocytes detach from the cytophore and float in the coelom; they are usually enveloped by the peritoneal epithelium and associated with blood vessels. Generally, the organization of ovaries in all of the Tubificinae species studied resembles the polarized ovary cords found within the ovisacs of some Euhirudinea. The organization of ovaries and the course of oogenesis between the genera studied and other clitellate annelids are compared. Finally, it is suggested that germ-line cysts formation and the meroistic mode of oogenesis may be a primary character for all Clitellata

    Decline in age at menarche among Spanish women born from 1925 to 1962

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    <p>Abstract</p> <p>Background</p> <p>While the timing of reproductive events varies across populations, a downward trend in age at menarche has nevertheless been reported in most of the developed world over the past century. Given the impact of change in age at menarche on health conditions, this study sought to examine secular trends in age at menarche among women living in Navarre (Northern Spain) who participated in a population-based breast cancer screening programme.</p> <p>Methods</p> <p>The study was based on 110545 women born from 1925 to 1962. Trends were tested using a linear regression model, in which year of birth was entered continuously as the predictor and age at menarche (years) as the response variable, using size of town and region of birth as covariates.</p> <p>Results</p> <p>Among women born in Navarre between 1925 and 1962, age at menarche declined steadily from an average of 13.72 years in the 1925-1929 birth-cohorts to 12.83 years in the 1958-1962 birth-cohorts. Controlling for size of town or city of birth, age at menarche declined by an average of 0.132 years every 5 years over the period 1925-1962. This decline was greater in women born in rural versus urban settings. Trends were also different among regions of birth.</p> <p>Conclusion</p> <p>We report a population-based study showing a downward trend in age of onset of menarche among Spanish women born in the period 1925-1962, something that is more pronounced among women born in rural settings and varies geographically.</p
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