Microalgae, including cyanobacteria, represent a valuable source of natural compounds that have remarkable bioactive properties. Each microalga species produces a mixture of antioxidants with ...different amounts of each compound. Three aspects are important in the production of bioactive compounds: the microalga species, the medium composition including light supplied and the photobioreactor design, and operation characteristics. In this study, the antioxidant content and productivity performance of four microalgae were assessed in batch and continuous cultures. Biomass productivity by the four microalgae was substantially enhanced under continuous cultivation by 5.9 to 6.3 times in comparison with batch cultures. The energetic yield, under the experimental conditions studied, ranged from 0.03 to 0.041 g biomass kJ
. Phenols, terpenoids, and alkaloids were produced by
,
, and
, whereas tocopherols and carotenoids were produced by the four microalgae, except for phycocyanin and allophycocyanin, which were only produced by
and
. The findings demonstrate that the continuous cultivation of microalgae in photobioreactors is a convenient method of efficiently producing antioxidants.
ABSTRACT ALMA Cycle 2 observations of long-wavelength dust emission in 145 star-forming galaxies are used to probe the evolution of the star-forming interstellar medium (ISM). We also develop a ...physical basis and empirical calibration (with 72 low-z and z ∼ 2 galaxies) for using the dust continuum as a quantitative probe of ISM masses. The galaxies with the highest star formation rates (SFRs) at = 2.2 and 4.4 have gas masses up to 100 times that of the Milky Way and gas mass fractions reaching 50%-80%, i.e., gas masses 1-4× their stellar masses. We find a single high-z star formation law: yr−1-an approximately linear dependence on the ISM mass and an increased star formation efficiency per unit gas mass at higher redshift. Galaxies above the main sequence (MS) have larger gas masses but are converting their ISM into stars on a timescale only slightly shorter than those on the MS; thus, these "starbursts" are largely the result of having greatly increased gas masses rather than an increased efficiency of converting gas to stars. At z > 1, the entire population of star-forming galaxies has ∼2-5 times shorter gas depletion times than low-z galaxies. These shorter depletion times indicate a different mode of star formation in the early universe-most likely dynamically driven by compressive, high-dispersion gas motions-a natural consequence of the high gas accretion rates.
Context.
The Mid-Infrared Instrument (MIRI) onboard the
James Webb
Space Telescope (JWST) will provide imaging, coronagraphy, low-resolution spectroscopy, and medium-resolution spectroscopy at ...unprecedented sensitivity levels in the mid-infrared wavelength range. The Medium Resolution Spectrometer (MRS) of MIRI is an integral field spectrograph that provides diffraction-limited spectroscopy between 4.9 and 28.3 μm, within a field of view (FOV) varying from ∼13 to ∼56 arcsec square. The design for MIRI MRS conforms with the goals of the JWST mission to observe high redshift galaxies and to study cosmology as well as observations of galactic objects, and stellar and planetary systems.
Aims.
From ground testing, we calculate the physical parameters essential for general observers and calibrating the wavelength solution and resolving power of the MRS which is critical for maximizing the scientific performance of the instrument.
Methods.
We have used ground-based observations of discrete spectral features in combination with Fabry-Perot etalon spectra to characterize the wavelength solution and spectral resolving power of the MRS. We present the methodology used to derive the MRS spectral characterization, which includes the precise wavelength coverage of each MRS sub-band, computation of the resolving power as a function of wavelength, and measuring slice-dependent spectral distortions.
Results.
The ground calibration of the MRS shows that it will cover the wavelength ranges from 4.9 to 28.3 μm, divided in 12 overlapping spectral sub-bands. The resolving power is
R
≳ 3500 in channel 1,
R
≳ 3000 in channel 2,
R
≳ 2500 in channel 3, and
R
≳ 1500 in channel 4. The MRS spectral resolution optimizes the sensitivity for detection of spectral features with a velocity width of ∼100 km s
−1
which is characteristic of most astronomical phenomena JWST aims to study in the mid-infrared. Based on the ground test data, the wavelength calibration accuracy is estimated to be below one-tenth of a pixel (0.1 nm at 5 μm and 0.4 at 28 μm), with small systematic shifts due to the target position within a slice for unresolved sources that have a maximum amplitude of about 0.25 spectral resolution elements. The absolute wavelength calibration is presently uncertain at the level of 0.35 nm at 5 μm and 46 nm at 28 μm, and it will be refined using in-flight commissioning observations.
Conclusions.
Based on ground test data, the MRS complies with the spectral requirements for both the
R
and wavelength accuracy for which it was designed. We also present the commissioning strategies and targets that will be followed to update the spectral characterization of the MRS.
We present MIRI/JWST medium-resolution spectroscopy (MRS) and imaging (MIRIM) of the lensed galaxy MACS1149-JD1 at a redshift of z = 9.1092 ± 0.0002, when the Universe was about 530 Myr old. We ...detect, for the first time, spatially resolved H α emission in a galaxy at a redshift above nine. The structure of the H α emitting gas consists of two clumps, S and N, carrying about 60% and 40% of the total flux, respectively. The total H α luminosity implies an instantaneous star-formation rate in the range of 3.2 ± 0.3 and 5.3 ± 0.4 M ⊙ yr −1 for sub-solar and solar metallicities. The ionizing photon production efficiency, log( ζ ion ), shows a spatially resolved structure with values of 25.55 ± 0.03; 25.47 ± 0.03; and 25.91 ± 0.09 Hz erg −1 for the integrated galaxy and clumps S and N, respectively. The H α rest-frame equivalent width, EW 0 (H α ), is 726 −182 +660 Å for the integrated galaxy, but it presents extreme values of 531 −96 +300 Å and ≥1951 Å for clumps S and N, respectively. The spatially resolved ionizing photon production efficiency is within the range of values measured in galaxies at a redshift above six and well above the canonical value (25.2 ± 0.1 Hz erg −1 ). The EW 0 (H α ) is a factor of two lower than the predicted value at z = 9.11 based on the extrapolation of the evolution of the EW 0 (H α ) with redshifts, ∝(1 + z ) 2.1 , including galaxies detected with JWST. The extreme difference of the EW 0 (H α ) for clumps S and N indicates the presence of a recent (< 5 Myr) stellar burst in clump N and a star formation over a larger period of time (e.g., ∼50 Myr) in clump S. The different ages of the stellar population place MACS1149-JD1 and clumps N and S at different locations in the log( ζ ion ) to EW 0 (H α ) plane and above the main relation defined from intermediate- and high-redshift ( z = 3 − 7) galaxies detected with JWST. Finally, clump S and N show very different H α kinematics, with velocity dispersions of 56 ± 4 km s −1 and 113 ± 33 km s −1 , likely indicating the presence of outflows or increased turbulence in clump N. The dynamical mass M dyn = (2.4 ± 0.5) × 10 9 M ⊙ , obtained from the size of the integrated H α ionized nebulae and its velocity dispersion, is within the range previously measured with the spatially resolved OIII88 μm line.
ABSTRACT
We report the discovery of J0121+0025, an extremely luminous and young star-forming galaxy (MUV = −24.11, log$L_{\rm Ly \alpha } / \rm erg~s^{-1} = 43.8$) at z = 3.244 showing copious Lyman ...continuum (LyC) leakage ($f_{\rm esc, abs} \approx 40{{\ \rm per\ cent}}$). High signal-to-noise ratio rest-frame UV spectroscopy with the Gran Telescopio Canarias reveals a high significance (7.9σ) emission below the Lyman limit (<912 Å), with a flux density level f900 = 0.78 ± 0.10μJy, and strong P-Cygni in wind lines of O vi 1033 Å, N v 1240 Å, and C iv 1550 Å that are indicative of a young age of the starburst (<10 Myr). The spectrum is rich in stellar photospheric features, for which a significant contribution of an AGN at these wavelengths is ruled out. Low-ionization interstellar medium (ISM) absorption lines are also detected, but are weak ($EW_{0} \rm \simeq 1$ Å) and show large residual intensities, suggesting a clumpy geometry of the gas with a non-unity covering fraction or a highly ionized ISM. The contribution of a foreground and AGN contamination to the LyC signal is unlikely. Deep optical to Spitzer/IRAC 4.5 μm imaging show that the spectral energy distribution of J0121+0025 is dominated by the emission of the young starburst, with log($M_{\star }^{\rm burst}/M_{\odot }) = 9.9\pm 0.1$ and $\rm SFR = 981\pm 232$ M⊙ yr−1. J0121+0025 is the most powerful LyC emitter known among the star-forming galaxy population. The discovery of such luminous and young starburst leaking LyC radiation suggests that a significant fraction of LyC photons can escape in sources with a wide range of UV luminosities and are not restricted to the faintest ones as previously thought. These findings might shed further light on the role of luminous starbursts to the cosmic reionization.
Aims. This work explores, from a statistical point of view, the rest-frame far-ultraviolet (FUV) to far-infrared (FIR) emission of a population of Lyman-break galaxies (LBGs) at z ∼ 3 that cannot be ...individually detected from current FIR observations. Methods. We performed a stacking analysis over a sample of ∼17 000 LBGs at redshift 2.5 < z < 3.5 in the COSMOS field. The sample is binned as a function of UV luminosity (LFUV), UV continuum slope (βUV), and stellar mass (M*), and then stacked at optical (BVriz bands), near-infrared (YJHKs bands), IRAC (3.6, 4.5, 5.6, and 8.0 μm), MIPS (24 μm), PACS (100 and 160 μm), SPIRE (250, 350, and 500 μm), and AzTEC (1.1 mm) observations. We obtained 30 rest-frame FUV-to-FIR spectral energy distributions (SEDs) of LBGs at z ∼ 3, and analyzed these with the CIGALE SED-fitting analysis code. We were able to derive fully consistent physical parameters, that is, M*, βUV, LFUV, LIR, AFUV, star formation rate, and the slope of the dust attenuation law; we built a semiempirical library of 30 rest-frame FUV-to-FIR stacked LBG SEDs as functions of LFUV, βUV, and M*. Results. We used the so-called IR-excess (IRX ≡ LIR/LFUV) to investigate the dust attenuation as a function of βUV and M*. Our LBGs, averaged as a function of βUV, follow the well-known IRX–βUV calibration of local starburst galaxies. Stacks as a function of M* follow the IRX–M* relationship presented in the literature at high M* (log(M* M⊙) > 10). However, a large dispersion is shown in the IRX–βUV and IRX–M* planes, in which the βUV and M* are combined to average the sample. Additionally, the SED-fitting analysis results provide a diversity of dust attenuation curve along the LBG sample, and their slopes are well correlated with M*. Steeper dust attenuation curves than Calzetti’s are favored in low stellar mass LBGs (log(M* M⊙) < 10.25), while grayer dust attenuation curves are favored in high stellar mass LBGs (log(M* M⊙) > 10.25). We also demonstrate that the slope of the dust attenuation curves is one of the main drivers that shapes the IRX–βUV plane.
Abstract
We describe an algorithm for application of the classic “drizzle” technique to produce 3D spectral cubes using data obtained from the slicer-type integral field unit (IFU) spectrometers on ...board the James Webb Space Telescope. This algorithm relies upon the computation of overlapping volume elements (composed of two spatial dimensions and one spectral dimension) between the 2D detector pixels and the 3D data cube voxels, and is greatly simplified by treating the spatial and spectral overlaps separately at the cost of just 0.03% in spectrophotometric fidelity. We provide a matrix-based formalism for the computation of spectral radiance, variance, and covariance from arbitrarily dithered data and comment on the performance of this algorithm for the Mid-Infrared Instrument’s Medium Resolution IFU Spectrometer. We derive a series of simplified scaling relations to account for covariance between cube spaxels in spectra extracted from such cubes, finding multiplicative factors ranging from 1.5–3 depending on the wavelength range and kind of data cubes produced. Finally, we discuss how undersampling produces periodic amplitude modulations in the extracted spectra in addition to those naturally produced by fringing within the instrument; reducing such undersampling artifacts below 1% requires a four-point dithering strategy and spectral extraction radii of 1.5 times the point-spread function FWHM or greater.
Project title: Occupational therapy and professional identity: narratives of professionals through life history. Study Protocol. Design: Qualitative research, using a socio-critical paradigm and ...biographical-narrative method where participants were selected through theoretical sampling and snowball sampling strategy. Data collection techniques were life stories, constructed through biograms, self-reports and biographical interviews. Abductive reasoning was used along with structural analysis techniques, narrative analysis, and ATLAS. ti software. Objective: To describe and analyze the occupational construct of the professional identity of occupational therapists in Spain. Specific Objectives: (1) Analyze life events, transitions, and turning points that contribute to the outlining of the life journey of professional identity. (2) Explore the management of professional tasks. (3) Analyze the nature of the knowledge required to carry out the role. (4) Examine in detail the strategies applied to the personal engagement of occupational therapists. Study Population and Total Number of Participants: The study population consisted of professionals who are currently working as occupational therapists in Spain. The number of participants was established when data saturation was reached, with a total of nine informants.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Members of the family Rhinonyssidae are tiny hematophagous endoparasitic mites that inhabit the nasal cavities of birds and can cause trauma to their hosts. Traditionally, identifying species in this ...group has relied on observing their morphometrical characteristics. Nevertheless, determining species within this particular group has become more challenging due to the rising number of newly discovered species. Moreover, the morphometrical traits vary depending on the specific genus or group of species being studied. In this study, the complete internal transcribed spacer ITS1, 5.8S rDNA, and ITS2 regions of the ribosomal DNA from eighteen species of rhinonyssid mites belonging to four genera were sequenced to assess the utility of this genomic region in resolving taxonomic questions in this group and to estimate the phylogenetic relationships among the species. Mites were collected by dissecting the nasal cavities of birds under a stereomicroscope. Specimens used for morphometrical analyses were cleared in 85% lactic acid for 1-48 h and mounted in Hoyer's medium. Other specimens were preserved at -20 °C for molecular studies. From the data obtained in this study, it can be concluded that a thorough review and an accurate morphometrical identification and determination of the discriminatory traits are needed in this group of mites. Moreover, although the ITS1-5.8S-ITS2 fragment solves different taxonomic and phylogenetic problems at the species level, it would be necessary to test new molecular markers, or even a combination of nuclear and mitochondrial markers or different domains of the nuclear 28S rDNA, to discover a reliable taxonomic situation for rhinonyssids.
ABSTRACT
We present the discovery and analysis of J1316+2614 at z = 3.6130, a UV-bright star-forming galaxy (MUV ≃ −24.7) with large escape of Lyman continuum (LyC) radiation. J1316+2614 is a young ...(≃10 Myr) star-forming galaxy with SFR ≃ 500 M⊙ yr−1 and a starburst mass of log(M⋆/M⊙) ≃ 9.7. It shows a very steep UV continuum, βUV = −2.59 ± 0.05, consistent with residual dust obscuration, E(B − V) ≃ 0. LyC emission is detected with high significance (≃17σ) down to 830 Å, for which a very high relative (absolute) LyC escape fraction $f_{\rm esc} \rm (LyC) \simeq 0.92$ (≃0.87) is inferred. The contribution of a foreground or active galactic nucleus contamination to the LyC signal is discussed, but is unlikely. J1316+2614 is the most powerful ionizing source known among the star-forming galaxy population, both in terms of production (QH ≈ 1056 s−1) and escape of ionizing photons ($f_{\rm esc} \rm (LyC) \approx 0.9$). Nebular emission in Ly α, H β, and other rest-frame optical lines are detected, but these are weak ($EW_{0} \rm H\beta \simeq 35$ Å), with their strengths reduced roughly by $\simeq 90{{\ \rm per\ cent}}$. J1316+2614 is the first case known where the effect of large escape of ionizing photons on the strength of nebular lines and continuum emission is clearly observed. Gas inflows are detected in J1316+2614 from the blue-dominated peak Ly α emission (with a blue-to-red peak line ratio Iblue/Ired ≃ 3.7) and redshifted interstellar medium absorption (≃100 km s−1). Our results suggest that J1316+2614 is undergoing a gas compaction event, possibly representing a short-lived phase in the evolution of massive and compact galaxies, where strong gas inflows have triggered an extreme star formation episode and nearly 100 per cent LyC photons are escaping.
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