scholarly journals Evolutionary Studies of Galaxies at Intermediate Redshifts

1990 ◽  
Vol 43 (2) ◽  
pp. 271
Author(s):  
WJ Couch
Keyword(s):  
Star Formation ◽  
Spectroscopic Studies ◽  
Density Field ◽  
Low Density ◽  
Triggering Mechanism ◽  
Evolution Of Galaxies ◽  
Distant Galaxies ◽  
Evolutionary Studies ◽  
Intermediate Redshifts

Photometric and spectroscopic studies of cluster and field galaxies out to redshifts of -0�5 have provided clear evidence for strong evolution over recent epochs. The development of this picture is reviewed by contrasting and comparing the investigations of distant galaxies in rich clusters and the low density field. A common link is found in that the evolution of galaxies in both environments is related to short-lived bursts of star formation. The triggering mechanism for these bursts is discussed with special attention being paid to the role of galaxy merging

scholarly journals The Metallicity Evolution of Galaxies through the Cosmic Epochs

2010 ◽  
Vol 6 (S277) ◽  
pp. 170-173
Author(s):  
R. Maiolino
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Optical Observations ◽  
Fundamental Relation ◽  
Evolution Of Galaxies ◽  
Spatially Resolved ◽  
Near Ir ◽  
Distant Galaxies ◽  
Central Regions ◽  
Low Metallicity

AbstractWe have found that local galaxies follow a very tight relation between gas metallicity, stellar mass and SFR, suggesting that their evolution is characterized by a long standing equilibrium between gas inflows, outflows and star formation. Surprisingly, even distant galaxies, out to z < 2.5, follow the same relation, suggesting that the same dominant mechanism of galaxy evolution is in place at any epoch, out to z < 2.5. However, by using deep near-IR spectroscopy (probing optical nebular lines at high-z), we find that galaxies at z > 3 deviate from such fundamental relation, by being significantly more metal poor. Spatially resolved metallicity maps of z > 3 disk galaxies reveal that they are characterized by central regions with low metallicity associated with the peak of star formation, indicating that the latter is due to massive inflow of pristine gas that both boosts star formation and dilutes the gas metallicity. Overall these results suggest that the metallicity evolution of galaxies at z > 3 is due to an excess of gas inflow at such early epochs, as expected by some recent models. Finally, we investigate the metallicity of merging systems, both locally and at high-z. By exploiting recent Herschel data, we have found that in these systems the dust content directly measured through the FIR-submm data is much higher than inferred from the metallicity measured through the optical nebular lines. The latter result suggests that, in these heavily obscured systems, optical observations only probe the outer, less enriched regions and are not representative of the bulk of the metal content.

scholarly journals The evolution of massive stars

1997 ◽  
Vol 189 ◽  
pp. 313-322 ◽  
Author(s):  
A. Maeder
Keyword(s):  
Star Formation ◽  
Uv Radiation ◽  
Chemical Evolution ◽  
Interstellar Dust ◽  
Galactic Center ◽  
Massive Stars ◽  
Galactic Nuclei ◽  
Proper Understanding ◽  
Evolution Of Galaxies ◽  
Distant Galaxies

Massive stars are the crossroads of many important astrophysical problems and thus a proper understanding of their evolution is very needed. They are the main sources of UV radiation, by heating the interstellar dust they produce the far-IR luminosities of galaxies. They are the precursors of Supernovae and also the main sources of nucleosynthesis. They are visible in distant galaxies and the recent observations of starbursts have shown their major role in the spectral and chemical evolution of galaxies. They begin to be observed in the galactic center and in regions of star formation around galactic nuclei.

The role of interstellar filaments in shaping the IMF and regulating star formation

2015 ◽  
Vol 75-76 ◽  
pp. 137-141
Author(s):  
P. André ◽  
V. Könyves ◽  
A. Roy
Keyword(s):  
Star Formation ◽  
The Imf

Structural, magnetic and Mössbauer spectroscopic studies of the [Fe(3-bpp)2](CF3COO)2 complex: role of crystal packing leading to an incomplete Fe(ii) high spin ⇋ low spin transition

CrystEngComm ◽  
2021 ◽  
Vol 23 (15) ◽  
pp. 2854-2861
Author(s):  
Kristian Handoyo Sugiyarto ◽  
Djulia Onggo ◽  
Hiroki Akutsu ◽  
Varimalla Raghavendra Reddy ◽  
Hari Sutrisno ◽  
...  
Keyword(s):  
High Spin ◽  
Crystal Packing ◽  
Spin Transition ◽  
Spectroscopic Studies ◽  
Mononuclear Complex

Mononuclear complex [Fe(3-bpp)2](CF3COO)2 exhibits a thermal (HS + HS) ⇋ (HS + LS) transition at ∼226 K which is not associated with any crystallographic transition.

scholarly journals FRI0376 EFFECT OF CARBAMYLATED LOW-DENSITY LIPOPROTEINS ON BONE CELLS HOMEOSTASIS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 784.2-785
Author(s):  
B. Lucchino ◽  
M. Leopizzi ◽  
T. Colasanti ◽  
V. DI Maio ◽  
C. Alessandri ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Bone Cells ◽  
Osteoclast Differentiation ◽  
Low Density Lipoproteins ◽  
Tartrate Resistant Acid Phosphatase ◽  
Low Density ◽  
Bone Homeostasis ◽  
Research Support ◽  
Erosive Disease

Background:Carbamylation is a post-translational modification occurring under several conditions such as uremia, smoking and chronic inflammation as in rheumatoid arthritis (RA). Low-density lipoproteins (LDL) represent a target of carbamylation. Carbamylated-LDL (cLDL) have an increased inflammatory and atherogenic potential. Growing evidence supports an influence of modified lipids on bone cells homeostasis. However, the role of cLDL on bone cells physiology is still unknown.Objectives:Considering the rate of carbamylation and the role of anti-carbamylated proteins antibodies as markers of erosive disease in RA, the purpose of this study is to investigate the effect of cLDL on bone homeostasis.Methods:In-vitrocarbamylation of LDL was performed as previously described by Ok et al. (Kidney Int. 2005). Briefly, native LDL (nLDL) were treated with potassium cyanate (KOCN) for 4 hours, followed by excessive dialysis for 36 hours to remove KOCN. Both osteoclasts (OCs) and osteoblasts (OBLs) were treated at baseline with 20 μg/ml, 100 μg/ml and 200 μg/ml of cLDL or nLDL. To induce osteoclast differentiation, CD14+ monocytes were isolated from peripheral blood of healthy donors by magnetic microbeads separation and then cultured on a 96-wells plate in DMEM media supplemented with RANKL and M-CSF. After 10 days cells were fixed, stained for tartrate-resistant acid phosphatase (TRAP), a marker of OC differentiation, and counted. OBLs were isolated from bone specimens of 3 patients who had undergone to knee or hip arthroplasty for osteoarthritis and treated for 5 days with different concentrations of cLDL and nLDL. OBLs were fixed and stained for alkaline phosphatase positive activity (ALP), a marker of osteogenic differentiation. Total RNA was extracted from cell lysates. Copies of single-stranded complementary DNA (cDNA) were synthesized and analyzed by real-time PCR to evaluate RANKL and Osteoprotegerin (OPG) mRNA expression levels.Results:In OCLs culture, cLDL significantly decreased the number of OC compared to untreated cells (200 μg/ml p=0,0015) and nLDL treated cells (200 μg/ml p= 0,011; 20 μg/ml p= 0,0014) (Fig 1). Moreover, treatment with cLDL induced an increase of not terminally differentiated OCs, reduced dimensions of OCs, less intense TRAP staining and vacuolization (Fig 2). In OBLs culture, cLDL (20, 100 μg/ml) significantly reduced the ALP activity of OBLs compared with untreated cells (p<0.05) (Fig 3). nLDL did not affect the ALP expression. Treatment with cLDL stimulated RANKL mRNA expression in osteoblasts increasing the RANKL/OPG ratio (Fig 4).Fig 1.Fig 2.Fig 3.Fig 4.Conclusion:cLDL induce a significant depression of OC and OBL differentiation. Moreover, cLDL increase RANKL expression in OBL, unbalancing bone tissue turnover towards bone resorption. Accordingly, cLDL could be implicated in the bone loss characterizing several conditions associated to an increased carbamylation, such as RADisclosure of Interests:Bruno Lucchino: None declared, Martina Leopizzi: None declared, Tania Colasanti: None declared, Valeria Di Maio: None declared, cristiano alessandri Grant/research support from: Pfizer, Guido Valesini: None declared, fabrizio conti Speakers bureau: BMS, Lilly, Abbvie, Pfizer, Sanofi, Manuela Di Franco: None declared, Francesca Romana Spinelli Grant/research support from: Pfizer, Consultant of: Novartis, Gilead, Lilly, Sanofi, Celgene, Speakers bureau: Lilly

scholarly journals The role of mergers and interactions in driving the evolution of dwarf galaxies over cosmic time

2020 ◽  
Vol 500 (4) ◽  
pp. 4937-4957 ◽  
Author(s):  
G Martin ◽  
R A Jackson ◽  
S Kaviraj ◽  
H Choi ◽  
J E G Devriendt ◽  
...  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxies ◽  
Large Fraction ◽  
Structural Evolution ◽  
Cosmic Time ◽  
Stellar Mass ◽  
High Mass ◽  
Key Drivers ◽  
Mass Assembly

ABSTRACT Dwarf galaxies (M⋆ &lt; 109 M⊙) are key drivers of mass assembly in high-mass galaxies, but relatively little is understood about the assembly of dwarf galaxies themselves. Using the NewHorizon cosmological simulation (∼40 pc spatial resolution), we investigate how mergers and fly-bys drive the mass assembly and structural evolution of around 1000 field and group dwarfs up to z = 0.5. We find that, while dwarf galaxies often exhibit disturbed morphologies (5 and 20 per cent are disturbed at z = 1 and z = 3 respectively), only a small proportion of the morphological disturbances seen in dwarf galaxies are driven by mergers at any redshift (for 109 M⊙, mergers drive under 20 per cent morphological disturbances). They are instead primarily the result of interactions that do not end in a merger (e.g. fly-bys). Given the large fraction of apparently morphologically disturbed dwarf galaxies which are not, in fact, merging, this finding is particularly important to future studies identifying dwarf mergers and post-mergers morphologically at intermediate and high redshifts. Dwarfs typically undergo one major and one minor merger between z = 5 and z = 0.5, accounting for 10 per cent of their total stellar mass. Mergers can also drive moderate star formation enhancements at lower redshifts (3 or 4 times at z = 1), but this accounts for only a few per cent of stellar mass in the dwarf regime given their infrequency. Non-merger interactions drive significantly smaller star formation enhancements (around two times), but their preponderance relative to mergers means they account for around 10 per cent of stellar mass formed in the dwarf regime.

scholarly journals Identification of an Immature Subset of PMN-MDSC Correlated to Response to Checkpoint Inhibitor Therapy in Patients with Metastatic Melanoma

Cancers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1362
Author(s):  
Françoise Gondois-Rey ◽  
Magali Paul ◽  
Florence Alcaraz ◽  
Sarah Bourass ◽  
Jilliana Monnier ◽  
...  
Keyword(s):  
Metastatic Melanoma ◽  
Checkpoint Inhibitor ◽  
T Cell Proliferation ◽  
Low Density ◽  
Direct Cytotoxicity ◽  
Radiological Response ◽  
Checkpoint Inhibitor Therapy ◽  
Pre Treatment ◽  
Immature Cells

PMN-MDSCs support tumor progression and resistance to ICI therapy through their suppressive functions but their heterogeneity limits their use as biomarkers in cancer. Our aim was to investigate the phenotypic and functional subsets of PMN-MDSCs to identify biomarkers of response to ICI therapy. We isolated low-density CD15+ PMNs from patients with metastatic melanoma and assessed their immune-suppressive capacities. Expression of CD10 and CD16 was used to identify mature and immature subsets and correlate them to inhibition of T cell proliferation or direct cytotoxicity. Frequencies of the PMN-MDSCs subsets were next correlated to the radiological response of 36 patients receiving ICI therapy. Mature activated cells constituted the major population of PMN-MDSCs. They were found in a higher proportion in the pre-treatment blood of patients non responders to ICI. A subset of immature cells characterized by intermediate levels of CD10 and CD16, the absence of expression of SIRPα and a strong direct cytotoxicity to T cells was increased in patients responding to ICI. The paradoxical expansion of such cells during ICI therapy suggests a role of PMNs in the inflammatory events associated to efficient ICI therapy and the usefulness of their monitoring in patients care.

scholarly journals Experimental and Theoretical Studies of Sonically Prepared Cu–Y, Cu–USY and Cu–ZSM-5 Catalysts for SCR deNOx

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 824
Author(s):  
Przemysław J. Jodłowski ◽  
Izabela Czekaj ◽  
Patrycja Stachurska ◽  
Łukasz Kuterasiński ◽  
Lucjan Chmielarz ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Ultrasonic Irradiation ◽  
Active Phase ◽  
Spectroscopic Studies ◽  
In Situ Drifts ◽  
Ft Ir ◽  
Diffuse Reflectance Infrared ◽  
Experimental And Theoretical Studies

The objective of our study was to prepare Y-, USY- and ZSM-5-based catalysts by hydrothermal synthesis, followed by copper active-phase deposition by either conventional ion-exchange or ultrasonic irradiation. The resulting materials were characterized by XRD, BET, SEM, TEM, Raman, UV-Vis, monitoring ammonia and nitrogen oxide sorption by FT-IR and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). XRD data confirmed the purity and structure of the Y/USY or ZSM-5 zeolites. The nitrogen and ammonia sorption results indicated that the materials were highly porous and acidic. The metallic active phase was found in the form of cations in ion-exchanged zeolites and in the form of nanoparticle metal oxides in sonochemically prepared catalysts. The latter showed full activity and high stability in the SCR deNOx reaction. The faujasite-based catalysts were fully active at 200–400 °C, whereas the ZSM-5-based catalysts reached 100% activity at 400–500 °C. Our in situ DRIFTS experiments revealed that Cu–O(NO) and Cu–NH3 were intermediates, also indicating the role of Brønsted sites in the formation of NH4NO3. Furthermore, the results from our experimental in situ spectroscopic studies were compared with DFT models. Overall, our findings suggest two possible mechanisms for the deNOx reaction, depending on the method of catalyst preparation (i.e., conventional ion-exchange vs. ultrasonic irradiation).

scholarly journals Population Density or Populations Size. Which Factor Determines Urban Traffic Congestion?

2021 ◽  
Vol 13 (8) ◽  
pp. 4280
Author(s):  
Yu Sang Chang ◽  
Sung Jun Jo ◽  
Yoo-Taek Lee ◽  
Yoonji Lee
Keyword(s):  
Population Density ◽  
Population Size ◽  
Traffic Congestion ◽  
Critical Role ◽  
Small Population ◽  
High Density ◽  
Urban Traffic ◽  
Contradictory Result ◽  
Low Density

A large number of articles have documented that as population density of cities increases, car use declines and public transit use rises. These articles had a significant impact of promoting high-density compact urban development to mitigate traffic congestion. Another approach followed by other researchers used the urban scaling model to indicate that traffic congestion increases as population size of cities increases, thus generating a possible contradictory result. Therefore, this study examines the role of both density and population size on traffic congestion in 164 global cities by the use of Stochastic Impacts by Regression on Population, Affluence and Technology model. We divide 164 cities into the two subgroups of 66 low density cities and 98 high density cities for analysis. The findings from the subgroups analysis indicated a clear-cut difference on the critical role of density in low-density cities and the exclusive role of population size in high-density cities. Furthermore, using threshold regression model, 164 cities are divided into the two regions of large and small population cities to determine population scale advantage of traffic congestion. Our findings highlight the importance of including analysis of subgroups based on density and/or population size in future studies of traffic congestion.

scholarly journals A Reference Sample: ISM of the Most Isolated Galaxies

2004 ◽  
Vol 217 ◽  
pp. 220-221
Author(s):  
L. Verdes-Montenegro ◽  
J. Sulentic ◽  
D. Espada ◽  
S. Leon ◽  
U. Lisenfeld ◽  
...  
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Galaxy Evolution ◽  
Reference Sample ◽  
Control Sample ◽  
Evolution Of Galaxies ◽  
Isolated Galaxies ◽  
Internal Evolution

We are constructing the first complete unbiased control sample of the most isolated galaxies of the northern sky to serve as a template in the study of star formation and galaxy evolution in denser environments. Our goal is to compare and quantify the properties of different phases of the interstellar medium in this sample, as well as the level of star formation, both relevant parameters in the internal evolution of galaxies and strongly conditioned by the environment. To achieve this goal we are building a multiwavelength database for this sample to compare and quantify the properties of different phases of the ISM.

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