This paper investigates the concept of cracking and overturning to analyze the impact of local density perturbations on the stability of self-gravitating compact objects in the framework of
f
(
R
,
ϕ
...,
X
)
theory of gravity, where
R
,
ϕ
, and
X
denote the Ricci scalar, scalar potential, and kinetic term, respectively. In this context, we developed the hydrostatic equilibrium equation for spherically symmetric spacetime with anisotropic matter configuration and subsequently employed the Krori Barua technique. We then perturb the hydrostatic equilibrium state of the configuration by employing the local density perturbation technique, while taking into account the barotropic equation of state. To validate this technique, we employed it on different compact stars namely, Her X-1, SAX J1808.4-3658, 4U 1820-30, PSR J1614-2230, Vela X-1, and Cen X-3, and found that all stars exhibit cracking or overturning for a specific range of model parameters. Conclusively, this study emphasizes that the proposed cracking technique provides significant insights into the stability analysis of self-gravitating compact objects.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Bone marrow derived mesenchymal stem cells (BM-MSCs) are used extensively in transplantation but their use is associated with many problems including low abundance in BM, low overall number, ...decreased differentiation potential with age and the invasive isolation procedures needed to obtain BM. We report a novel method of isolating placental MSCs (pMSCs) from chorionic villi, which exhibit the phenotypic and functional characteristics that will make them an attractive source of MSCs for cell-based therapy.
A novel explant approach was used to isolate pMSCs from chorionic villi of human placentae. These pMSCs were characterized by flow cytometry and were differentiated into adipocytes, osteocytes and chondrocytes using differentiation medium as demonstrated by cytochemical staining. The gene and protein expression profiles of pMSCs were also characterized using real time polymerase chain reaction (PCR) and flow cytometry, respectively. In addition, cytokine secretion by pMSCs was also analysed using sandwich enzyme-linked immunosorbent assay (ELISA) technique. Moreover, the migration and proliferation potentials of pMSCs were also determined.
pMSCs were isolated from fetal part of the chorionic villi and these pMSCs expressed CD44, CD90, CD105, CD146, CD166 and HLA-ABC but not CD14, CD19, CD40, CD45, CD80, CD83, CD86 and HLA-DR. In addition, these pMSCs differentiated into osteocytes, chondrocytes and adipocytes and they also expressed several adhesion molecules, chemokines/receptors, growth factor receptors and cytokines/receptors. Moreover, they secreted many cytokines (IL-1Ra, IL6, IL8, IL10, IL11 and IL15) and they were able to proliferate. Furthermore, they migrated in response to chemotactic factors including stromal cell-derived factor-1 (SDF-1), platelet derived growth factor (PDGF), hepatocyte growth factor (HGF), and monocyte chemotactic protein-1 (MCP-1).
We devised a novel explant method of isolating pMSCs that expressed many biological factors responsible for mediating cellular processes such as migration/homing, immune modulation and angiogenesis. Therefore, we suggest that pMSCs prepared from human term placental chorionic villous explants are an attractive source of MSCs for cell therapy.
Background
Mesenchymal stem cells (MSCs) have a therapeutic potential in tissue repair because of capacity for multipotent differentiation and their ability to modulate the immune response. In this ...study, we examined the ability of human placental MSCs (pMSCs) to modify the differentiation of human monocytes into macrophages and assessed the influence of pMSCs on important macrophage functions.
Methods
We used GM-CSF to stimulate the differentiation of monocytes into the M1 macrophage pathway and then co-cultured these cells with pMSCs in the early stages of macrophage differentiation. We then evaluated the effect on differentiation by microscopic examination and by quantification of molecules important in the differentiation and immune functions of macrophages using flow cytometry and ELISA. The mechanism by which pMSCs could mediate their effects on macrophage differentiation was also studied.
Results
The co-culture of pMSCs with monocytes stimulated to follow the inflammatory M1 macrophage differentiation pathway resulted in a shift to anti-inflammatory M2-like macrophage differentiation. This transition was characterized by morphological of changes typical of M2 macrophages, and by changes in cell surface marker expression including CD14, CD36, CD163, CD204, CD206, B7-H4 and CD11b, which are distinctive of M2 macrophages. Co-culture with pMSCs reduced the expression of the costimulatory molecules (CD40, CD80 and CD86) and increased the expression of co-inhibitory molecules (CD273, CD274 and B7-H4) as well as the surface expression of major histocompatibility complex (MHC-II) molecules. Furthermore, the secretion of IL-10 was increased while the secretion of IL-1β, IL-12 (p70) and MIP-1α was decreased; a profile typical of M2 macrophages. Finally, pMSCs induced the phagocytic activity and the phagocytosis of apoptotic cells associated with M2- like macrophages; again a profile typical of M2 macrophages. We found that the immunoregulatory effect of pMSCs on macrophage differentiation was mediated by soluble molecules acting partially via glucocorticoid and progesterone receptors.
Conclusions
We have shown that pMSCs can transition macrophages from an inflammatory M1 into an anti-inflammatory M2 phenotype. Our findings suggest a new immunosuppressive property of pMSCs that may be employed in the resolution of inflammation associated with inflammatory diseases and in tissue repair.
Abstract The aim of the present work was to evaluate and analyze the growth and mineral nutrition response of stone pine (Pinus pinea L.) seedlings, an economically important forest species. We ...analyzed the salinity effects on the kinetics of growth, development, and absorption of nutrients of plants cultivated under controlled conditions on a solid organic substrate. Pinus pinea plants were able to tolerate 25 mM NaCl concentration without reduced growth compared to the non-saline control. However, the salt concentration of 50 mM significantly affected the seedling growth after two weeks of treatment. Root growth activity was decreased more than the aerial parts at applied NaCl concentrations. On the other hand, seedlings restricted the transport of Na+ ions to the aerial parts and were strongly selective in favour of K+ ions. The presence of NaCl in the culture medium decreased the absorption rate and the export of K+ and Na+ ions to the aerial parts. This was reflected in the accumulation way of these two ions in the whole plant.
Resumo O objetivo do presente trabalho foi avaliar e analisar a resposta de crescimento e nutrição mineral de mudas de pinheiro-manso (Pinus pinea L.), uma espécie florestal economicamente importante. Analisamos os efeitos da salinidade na cinética de crescimento, desenvolvimento e absorção de nutrientes de plantas cultivadas sob condições controladas em substrato orgânico sólido. As plantas de P. pinea foram capazes de tolerar a concentração de 25 mM de NaCl sem redução do crescimento em comparação com o controle não salino. No entanto, a concentração de sal de 50 mM afetou significativamente o crescimento das plântulas após duas semanas de tratamento. A atividade de crescimento das raízes foi mais reduzida do que as partes aéreas nas concentrações de NaCl aplicadas. Por outro lado, as plântulas restringiram o transporte de íons Na+ para a parte aérea e foram fortemente seletivas em favor dos íons K+. A presença de NaCl no meio de cultura diminuiu a taxa de absorção e a exportação de íons K+ e Na+ para as partes aéreas. Isso se refletiu na forma de acúmulo desses dois íons em toda a planta.
In this paper, we present the first realisation and experimentation of a new eye tracking system using an infrared (iR) laser pointer embedded into a wireless smart contact lens. We denote this ...contact lens prototype as the cyclops lens, in reference to the famous hero of the X-Men comics. The full eye tracker device combines the smart contact lens and its eyewear, which provides a primary source of energy and the beam detection system. We detail the assembling and encapsulation process of the main functionalities into the contact lens and present how a gaze tracking system is achieved, compared to existing conventional eye-tracking ones. Finally, we discuss future technical improvements.
Mesenchymal stem cell (MSC) therapies for the treatment of diseases associated with inflammation and oxidative stress employ primarily bone marrow MSCs (BMMSCs) and other MSC types such as MSC from ...the chorionic villi of human term placentae (pMSCs). These MSCs are not derived from microenvironments associated with inflammation and oxidative stress, unlike MSCs from the decidua basalis of the human term placenta (DBMSCs). DBMSCs were isolated and then extensively characterized. Differentiation of DBMSCs into three mesenchymal lineages (adipocytes, osteocytes, and chondrocytes) was performed. Real-time polymerase chain reaction (PCR) and flow cytometry techniques were also used to characterize the gene and protein expression profiles of DBMSCs, respectively. In addition, sandwich enzyme-linked immunosorbent assay (ELISA) was performed to detect proteins secreted by DBMSCs. Finally, the migration and proliferation abilities of DBMSCs were also determined. DBMSCs were positive for MSC markers and HLA-ABC. DBMSCs were negative for hematopoietic and endothelial markers, costimulatory molecules, and HLA-DR. Functionally, DBMSCs differentiated into three mesenchymal lineages, proliferated, and migrated in response to a number of stimuli. Most importantly, these cells express and secrete a distinct combination of cytokines, growth factors, and immune molecules that reflect their unique microenvironment. Therefore, DBMSCs could be attractive, alternative candidates for MSC-based therapies that treat diseases associated with inflammation and oxidative stress.
According to the sixth assessment report of the Intergovernmental Panel on Climate Change (IPCC), global climate change is now unequivocal. Tunisia, like many other countries, has been affected by ...climate changes, including rising temperatures, intense heatwaves, and altered precipitation regimes. Tunisia's mean annual temperatures has risen about +1.4 °C in the twentieth century, with the most rapid warming taking place since the 1970s. Drought represents a primary contributing factor to tree decline and dieback. Long‐term drought can result in reduced growth and health of trees, thereby increasing their susceptibility to insect pests and pathogens. Reported increases in tree mortality point toward accelerating global forest vulnerability under hotter temperatures and longer, more intense droughts. In order to assess the effect of these climate changes on the current state of forest ecosystems in Tunisia and their evolution, an investigative study was required. Here, we review the current state of knowledge on the effects of climate change on sclerophyllous and semi‐deciduous forest ecosystems in Tunisia. Natural disturbance during recent years, as well as the adaptability and resilience of some forest species to climate change, were surveyed. The Standardized Precipitation Evapotranspiration Index (SPEI) is a multi‐scalar drought index based on climate data that has been used to analyse drought variability. The SPEI time scale analysis showed a negative trend over the 1955–2021 period in Tunisian forest regions. In 2021, Tunisia lost 280 km2 of tree cover to fires, which is equivalent to 26% of the total lost area between 2008 and 2021. Changing climate conditions have also affected phenological parameters, with an advance in the start of the green season (SOS) of 9.4 days, a delay at the end of the green season (EOS) of 5 days, with a consequent extended duration of the green season (LOS) by an average of 14.2 days. All of these alarming findings invite us to seek adaptation strategies for forest ecosystems. Adapting forests to climate change is therefore a challenge for scientists as well as policymakers and managers.
Emergent vulnerability to climate‐driven disturbances in Mediterranean forests: advancing the understanding resilience and adaptive capacity.
The design of the electrochromic component of an instrumented contact lens capable of dynamically modifying its color is presented. The device is based on two electrochromic pi-conjugated polymers ...(CPs) deposited on two electrodes separated by an electrolyte medium. Yellow and cyan electrochromic CPs with two color states are combined to provide a tuneable tint of the eye iris, from green to cyan. The device can switch from green, in which both electrodes are colored, to cyan, in which only the cyan electrode is colored. The additive microsystem process with successive assembling steps allowing the realization of the bichromatic cell in the scleral contact lens is presented, as well as the characterization of the colorimetry and switching dynamics.
Sirolimus was introduced in de novo immunosuppression at Stanford University in view of its favorable effects on reduced rejection and cardiac allograft vasculopathy. After an apparent increase in ...the incidence of post‐surgical wound complications as well as symptomatic pleural and pericardial effusions, we reverted to a mycophenolate mofetil (MMF)‐based regimen. This retrospective study compared the outcome in heart transplant recipients on sirolimus (48 patients) with those on MMF (46 patients) in de novo immunosuppressive regimen. The incidence of any post‐surgical wound complication (52% vs. 28%, p = 0.019) and deep surgical wound complication (35% vs. 13%, p = 0.012) was significantly higher in patients on sirolimus than on MMF. More patients on sirolimus also had symptomatic pleural (p = 0.035) and large pericardial effusions (p = 0.033) requiring intervention. Logistic regression analysis showed sirolimus (p = 0.027) and longer cardiac bypass time (OR = 1.011; p = 0.048) as risk factors for any wound complication. Sirolimus in de novo immunosuppression after cardiac transplantation was associated with a significant increase in the incidence of post‐surgical wound healing complications as well as symptomatic pleural and pericardial effusions.
Assessing the vulnerability of forest ecosystems in the climate change context is a challenging task as the mechanisms that determine this vulnerability cannot be directly observed. Based on the ...ecological interrelationships between forests and climate, the present review focused on providing current information about vulnerability assessments of cork oak (
Quercus suber
L.) forests in the Mediterranean basin, especially, in the Kroumirie region (northwest Tunisia), currently under historic extreme drought conditions. From comparing recent findings in this region, we synthesized data on cork oak decline and mortality collected during the historic drought years 1988–1995 period. Climate change impacts cork forest decline, with special interest shown in elevated temperatures and drought; cork oak forest regeneration, and the adaptation of the Kroumirie forest to climate change, are reviewed herein. The studied region has been influenced largely by frequent prolonged drought periods, especially from 1988 to 1995. Droughts were found to consistently have a more detrimental impact on the growth and mortality rates of cork oak populations. Cork oak mortality was recorded for up to 63,622 trees. In the future, more research studies and observational data will be needed, which could represent an important key to understand ecosystem processes, and to facilitate the development of better models that project climate change impacts and vulnerability. The study is useful for researchers and forestry decision makers to develop the appropriate strategies to restore and protect ecosystems, and to help anticipate potential future droughts and climate change.
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