140 research outputs found
TGR5: A Novel Target for Weight Maintenance and Glucose Metabolism
TGR5, an emerging G protein-coupled receptor, was identified as a membrane receptor for bile acids. The expression of TGR5 and its function are distinct from the previously identified nuclear bile acid receptor, farnesoid X receptor (FXR). These two bile acid receptors complement with each other for maintaining bile acid homeostasis and mediating bile acid signaling. Both receptors are also shown to play roles in regulating inflammation and glucose metabolism. An interesting finding for TGR5 is its role in energy metabolism. The discovery of TGR5 expression in brown adipocyte tissues (BATs) and the recent demonstration of BAT in adult human body suggest a potential approach to combat obesity by targeting TGR5 to increase thermogenesis. We summarize here the latest finding of TGR5 research, especially its role in energy metabolism and glucose homeostasis
An Yb3+-Ho3+ codoped glass microsphere laser in the 2.0μm wavelength regions
In this letter, an Yb 3+ -Ho 3+ codoped sol-gel silica microsphere lasing at around 2.0 μm is reported. The gain microsphere is fabricated by overlaying the 1.0 mol% Yb 3+ -0.2 mol% Ho 3+ codoped sol-gel solution on the surface of a pure silica microsphere and is then heated using a CO 2 laser. Using a traditional fiber taper-microsphere coupling method, we observe the single- and multi-mode microsphere laser outputs around 2.0 μm using a 980 nm laser diode as a pump source, with a low threshold pumping power of 14.7 mW. The ability to fabricate sol-gel codoped silica glass microlasers represents a new generation of low-threshold and compact mid-infrared laser sources for use as miniaturized photonic components for a wide range of applications including gas sensing and medical surgery
Statistical physics approaches to the complex Earth system
Global climate change, extreme climate events, earthquakes and their
accompanying natural disasters pose significant risks to humanity. Yet due to
the nonlinear feedbacks, strategic interactions and complex structure of the
Earth system, the understanding and in particular the predicting of such
disruptive events represent formidable challenges for both scientific and
policy communities. During the past years, the emergence and evolution of Earth
system science has attracted much attention and produced new concepts and
frameworks. Especially, novel statistical physics and complex networks-based
techniques have been developed and implemented to substantially advance our
knowledge for a better understanding of the Earth system, including climate
extreme events, earthquakes and Earth geometric relief features, leading to
substantially improved predictive performances. We present here a comprehensive
review on the recent scientific progress in the development and application of
how combined statistical physics and complex systems science approaches such
as, critical phenomena, network theory, percolation, tipping points analysis,
as well as entropy can be applied to complex Earth systems (climate,
earthquakes, etc.). Notably, these integrating tools and approaches provide new
insights and perspectives for understanding the dynamics of the Earth systems.
The overall aim of this review is to offer readers the knowledge on how
statistical physics approaches can be useful in the field of Earth system
science
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Statistical physics approaches to the complex Earth system
Global warming, extreme climate events, earthquakes and their accompanying socioeconomic disasters pose significant risks to humanity. Yet due to the nonlinear feedbacks, multiple interactions and complex structures of the Earth system, the understanding and, in particular, the prediction of such disruptive events represent formidable challenges to both scientific and policy communities. During the past years, the emergence and evolution of Earth system science has attracted much attention and produced new concepts and frameworks. Especially, novel statistical physics and complex networks-based techniques have been developed and implemented to substantially advance our knowledge of the Earth system, including climate extreme events, earthquakes and geological relief features, leading to substantially improved predictive performances. We present here a comprehensive review on the recent scientific progress in the development and application of how combined statistical physics and complex systems science approaches such as critical phenomena, network theory, percolation, tipping points analysis, and entropy can be applied to complex Earth systems. Notably, these integrating tools and approaches provide new insights and perspectives for understanding the dynamics of the Earth systems. The overall aim of this review is to offer readers the knowledge on how statistical physics concepts and theories can be useful in the field of Earth system science
In-fiber temperature sensor based on green up-conversion luminescence in an Er3+-Yb3+ co-doped tellurite glass microsphere
A novel, to the best of our knowledge, in-fiber temperature sensor based on green up-conversion (UC) luminescence in an Er3+-Yb3+ role= presentation style= box-sizing: border-box; display: inline; font-size: 12.88px; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; \u3eEr3+-Yb3+Er3+-Yb3+ co-doped tellurite glass microsphere is described. The tellurite glass microsphere is located firmly inside a suspended tri-core hollow-fiber (STCHF) structure. The pump light launched via a single-mode fiber (SMF) is passed through a section of multimode fiber, which is fusion spliced between the SMF and the STCHF into the cores suspended inside the hollow fiber and coupled into the microsphere. Green and red UC emissions of the Er3+ role= presentation style= box-sizing: border-box; display: inline; font-size: 12.88px; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; \u3eEr3+Er3+ ions are observed using 980 nm pump excitation. The temperature-sensing capability of the tellurite glass microsphere is based on the thermally coupled effect between the upper energy levels responsible for green emissions at 528 nm and 549 nm. The resulting fluorescence intensity ratio, depending on the surrounding temperature range from 303 K to 383 K, is experimentally determined, and a maximum sensitivity of 5.47×10−3 K−1 role= presentation style= box-sizing: border-box; display: inline; font-size: 12.88px; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative; \u3e5.47×10−3 K−15.47×10−3 K−1 is demonstrated. This novel in-fiber microsphere-resonator-based device is highly integrated and has the additional advantages of ease of fabrication, compact structure, and low fabrication cost and therefore has great application potential in integrated optical sources including lasers
National debt management and business sustainability in Africa’s largest economy: A focus on the private sector
In many developing economies, high and increasing public debt profile constitutes an essential
means of financial risk. An appropriate debt management is germane for survival of business
and good international reputation though its effect on private sector credit mobilization
had been seldomly investigated. This study seeks to know whether strategic debt management
approach exacts a significant effect on the Nigerian private sector and Africa at large
resulting to higher credit availability for sustainable enterprise establishment. The study
used a time-series observation spanning from 1981–2021. The method of data analysis
employed the unit root test for stationarity. Johansen cointegration and vector error correction
approach. The result of the unit root test indicates the series were all stationary after
first difference and thus were integrated of order1. The Johansen cointegration test support
the existence of a cointegrating series between the private credit and its determinants. More
empirical evidence from the study shows that proper debt management and increase revenue
generation through net taxes on products accounted for 0.93 and 1.32% increase in private
sector credit mobilization, while total external debt stock was responsible for a
significant negative influence of 0.60% on private sector credit mobilization. The study recommends
that the government should always be proactive in their strategic and innovative
approach to debt management, revenue generation and sources of funds. This will help not
only to avoid crowding out of the private sector but will enhance adequate credit mobilization
for effective operations of the private sector
Regional Greening as a `Positive' Tipping Phenomenon
Earth system tipping elements have been predominantly investigated for their
potential to trigger \textit{negative} ecological, climatic, and societal
shifts. Yet, an overlooked but seminal avenue exists in the form of
\textit{positive} tipping phenomena, whose underlying mechanisms and benefits
remain largely underexplored. To bridge this gap, our research introduces a
fundamental percolation-based framework to assess the criticality and
resilience of planetary terrestrial vegetation systems. Leveraging
high-resolution satellite data, we focus on greening-induced positive tipping
dynamics driven by global warming. We feature the Qinghai-Tibetan Plateau (QTP)
and the Sahel region as contrasting yet analogous case studies. Our analysis
uncovers an intriguing phenomenon where vegetation fragmentation aligns with a
percolation threshold, exhibiting a scale-invariant pattern characterized by
nearly perfect power laws with three critical exponents. Remarkably, contrary
to conventional destructive tipping elements, these regions act as favorable
tipping elements, transitioning from fragmented to cohesive vegetation patterns
due to anthropogenic climate change and afforestation efforts. Furthermore, we
propose an \textit{optimal resilience enhancement model} to reinforce
vegetation robustness while minimizing socio-economic costs. This study
provides valuable insights into the favorable aspects of tipping elements under
climate change and offers effective strategies for enhancing ecological
resilience against environmental threats
Teleconnections among tipping elements in the Earth system
Tipping elements are components of the Earth system that may shift abruptly and irreversibly from one state to another at specific thresholds. It is not well understood to what degree tipping of one system can influence other regions or tipping elements. Here, we propose a climate network approach to analyse the global impacts of a prominent tipping element, the Amazon Rainforest Area (ARA). We find that the ARA exhibits strong correlations with regions such as the Tibetan Plateau (TP) and West Antarctic ice sheet. Models show that the identified teleconnection propagation path between the ARA and the TP is robust under climate change. In addition, we detect that TP snow cover extent has been losing stability since 2008. We further uncover that various climate extremes between the ARA and the TP are synchronized under climate change. Our framework highlights that tipping elements can be linked and also the potential predictability of cascading tipping dynamics.Peer reviewe
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