Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
18,712
result(s) for
"M Yi"
Sort by:
Evaluating evidence in biological anthropology : the strange and the familiar
\"Biological anthropology is a diverse field, with countless research methods and techniques in different subdisciplines. This book takes a critical perspective to the current state of the field, exploring theory and practice in paleoanthropology, bioarchaeology, and ecology. Contributors challenge how evidence is discovered, collected, and interpreted, and explain that researchers gain insights by defamiliarizing themselves from well-known methods and taking a different perspective - \"making the familiar strange.\" The book covers how researchers' biases and assumptions affect the interpretation of topics such as human evolution and population movements; race, health, and disability; bodies and embodiment; and landscapes and ecology. A final chapter includes a critical assessment of new thinking about technology, in addition to the multilayered and complex nature of both research questions and evidence. This is an insightful text for researchers and graduate students in anthropology, biology, ecology, history, and philosophy of science\"-- Provided by publisher.
Book
Femtosecond electron-phonon lock-in by photoemission and x-ray free-electron laser
The interactions that lead to the emergence of superconductivity in iron-based materials remain a subject of debate. It has been suggested that electron-electron correlations enhance electron-phonon coupling in iron selenide (FeSe) and related pnictides, but direct experimental verification has been lacking. Here we show that the electron-phonon coupling strength in FeSe can be quantified by combining two time-domain experiments into a “coherent lock-in” measurement in the terahertz regime. X-ray diffraction tracks the light-induced femtosecond coherent lattice motion at a single phonon frequency, and photoemission monitors the subsequent coherent changes in the electronic band structure.Comparison with theory reveals a strong enhancement of the coupling strength in FeSe owing to correlation effects. Given that the electron-phonon coupling affects superconductivity exponentially, this enhancement highlights the importance of the cooperative interplay between electron-electron and electron-phonon interactions.
Journal Article
Atomic structure and domain wall pinning in samarium-cobalt-based permanent magnets
A higher saturation magnetization obtained by an increased iron content is essential for yielding larger energy products in rare-earth Sm
2
Co
17
-type pinning-controlled permanent magnets. These are of importance for high-temperature industrial applications due to their intrinsic corrosion resistance and temperature stability. Here we present model magnets with an increased iron content based on a unique nanostructure and -chemical modification route using Fe, Cu, and Zr as dopants. The iron content controls the formation of a diamond-shaped cellular structure that dominates the density and strength of the domain wall pinning sites and thus the coercivity. Using ultra-high-resolution experimental and theoretical methods, we revealed the atomic structure of the single phases present and established a direct correlation to the macroscopic magnetic properties. With further development, this knowledge can be applied to produce samarium cobalt permanent magnets with improved magnetic performance.
Understanding the factors that determine the properties of permanent magnets, which play a central role in many industrial applications, can help in improving their performance. Here, the authors study how changes in the iron content affect the microstructure of samarium cobalt magnets.
Journal Article
Interfacial mode coupling as the origin of the enhancement of Tc in FeSe films on SrTiO3
High-resolution angle-resolved photoemission spectroscopy reveals bosonic modes in a SrTiO
3
substrate coupling to electrons in an FeSe overlayer to facilitate high-temperature superconductivity.
Strontium titanate boosts supereconductivity
Bulk iron selenide (FeSe) is a superconductor with a critical temperature
T
c
= 8 K, but superconductivity is substantially enhanced in single-unit cell films of FeSe grown on strontium titanate (SrTiO
3
or STO) substrates, where superconducting energy gaps open at temperatures close to the boiling point of liquid nitrogen (77 K). This raises the question of whether the substrate has a contributory role in this enhancement. Zhi-Xun Shen and colleagues report high-resolution angle-resolved photoemission spectroscopy (ARPES) results that reveal bosonic modes (thought to be oxygen optical phonons) in the SrTiO
3
substrate coupling to electrons in the FeSe overlayer to facilitate high-temperature superconductivity. Such coupling helps superconductivity in most channels, so the pairing enhancement described here may well work for other superconducting materials, as well as for FeSe.
Films of iron selenide (FeSe) one unit cell thick grown on strontium titanate (SrTiO
3
or STO) substrates have recently shown
1
,
2
,
3
,
4
superconducting energy gaps opening at temperatures close to the boiling point of liquid nitrogen (77 kelvin), which is a record for the iron-based superconductors. The gap opening temperature usually sets the superconducting transition temperature
T
c
, as the gap signals the formation of Cooper pairs, the bound electron states responsible for superconductivity. To understand why Cooper pairs form at such high temperatures, we examine the role of the SrTiO
3
substrate. Here we report high-resolution angle-resolved photoemission spectroscopy results that reveal an unexpected characteristic of the single-unit-cell FeSe/SrTiO
3
system: shake-off bands suggesting the presence of bosonic modes, most probably oxygen optical phonons in SrTiO
3
(refs
5
,
6
,
7
), which couple to the FeSe electrons with only a small momentum transfer. Such interfacial coupling assists superconductivity in most channels, including those mediated by spin fluctuations
8
,
9
,
10
,
11
,
12
,
13
,
14
. Our calculations suggest that this coupling is responsible for raising the superconducting gap opening temperature in single-unit-cell FeSe/SrTiO
3
.
Journal Article
Genetic diversity, biofilm formation, and Vancomycin resistance of clinical Clostridium innocuum isolates
Background
Clostridium innocuum
, previously considered a commensal microbe, is a spore-forming anaerobic bacterium.
C
.
innocuum
displays inherent resistance to vancomycin and is associated with extra-intestinal infections, antibiotic-associated diarrhea, and inflammatory bowel disease. This study seeks to establish a multilocus sequence typing (MLST) scheme to explore the correlation between
C
.
innocuum
genotyping and its potential pathogenic phenotypes.
Methods
Fifty-two
C
.
innocuum
isolates from Linkou Chang Gung Memorial Hospital (CGMH) in Taiwan and 60 sequence-available
C
.
innocuum
isolates from the National Center for Biotechnolgy Information Genome Database were included. The concentrated sequence of housekeeping genes in
C
.
innocuum
was determined by amplicon sequencing and used for MLST and phylogenetic analyses. The biofilm production activity of the
C
.
innocuum
isolates was determined by crystal violet staining.
Results
Of the 112
C
.
innocuum
isolates, 58 sequence types were identified. Maximum likelihood estimation categorized 52 CGMH isolates into two phylogenetic clades. These isolates were found to be biofilm producers, with isolates in clade I exhibiting significantly higher biofilm production than isolates in clade II. The sub-inhibitory concentration of vancomycin seemed to minimally influence biofilm production by
C
.
innocuum
isolates. Nevertheless,
C
.
innocuum
embedded in the biofilm structure demonstrated resistance to vancomycin treatments at a concentration greater than 256 µg/mL.
Conclusions
This study suggests that a specific genetic clade of
C
.
innocuum
produces a substantial amount of biofilm. Furthermore, this phenotype assists
C
.
innocuum
in resisting high concentrations of vancomycin, which may potentially play undefined roles in
C
.
innocuum
pathogenesis.
Journal Article
Claudin-1 induces epithelial-mesenchymal transition through activation of the c-Abl-ERK signaling pathway in human liver cells
Claudins (CLDNs) are a family of integral membrane proteins central to the formation of tight junctions, structures that are involved in paracellular transport and cellular growth and differentiation, and are critical for the maintenance of cellular polarity. Recent studies have provided evidence that CLDNs are aberrantly expressed in diverse types of human cancers, including hepatocellular carcinomas (HCCs). However, little is known about how CLDN expression is involved in cancer progression. In this study, we show that CLDN1 has a causal role in the epithelial-mesenchymal transition (EMT) in human liver cells, and that the c-Abl-Ras-Raf-1-ERK1/2 signaling axis is critical for the induction of malignant progression by CLDN1. Overexpression of CLDN1 induced expression of the EMT-regulating transcription factors Slug and Zeb1, and thereby led to repression of E-cadherin, β-catenin expression, enhanced expression of N-cadherin and Vimentin, a loss of cell adhesion, and increased cell motility in normal liver cells and HCC cells. In line with these findings, inhibition of either c-Abl or ERK clearly attenuated CLDN1-induced EMT, as evidenced by a reversal of N-cadherin and E-cadherin expression patterns, and restored normal motility. Collectively, these results indicate that CLDN1 is necessary for the induction of EMT in human liver cells, and that activation of the c-Abl-Ras-Raf-1-ERK1/2 signaling pathway is required for CLDN1-induced acquisition of the malignant phenotype. The present observations suggest that CLDN1 could be exploited as a biomarker for liver cancer metastasis and might provide a pivotal point for therapeutic intervention in HCC.
Journal Article
The earliest human occupation of the high-altitude Tibetan Plateau 40 thousand to 30 thousand years ago
Human colonization of the high-altitude Tibetan Plateau has generally been thought to have been confined to the past few thousand years of the Holocene. Zhang et al. report an investigation of the Nwya Devu archaeological site in central Tibet, 4600 meters above sea level, with Paleolithic occupation dates of ∼40 thousand to 30 thousand years ago (see the Perspective by Zhang and Dennell). The site has yielded a range of stone tools, indicating the adaptive ability of early modern humans to the harsh environment of the “roof of the world.” The findings also suggest that people from Tibet and Siberia may have interacted at this time. Science , this issue p. 1049 ; see also p. 992 The Nwya Devu Paleolithic site in Tibet, 4600 meters above sea level, preserves evidence of early human high-altitude adaptation. The Tibetan Plateau is the highest and one of the most demanding environments ever inhabited by humans. We investigated the timing and mechanisms of its initial colonization at the Nwya Devu site, located nearly 4600 meters above sea level. This site, dating from 40,000 to 30,000 years ago, is the highest Paleolithic archaeological site yet identified globally. Nwya Devu has yielded an abundant blade tool assemblage, indicating hitherto-unknown capacities for the survival of modern humans who camped in this environment. This site deepens the history of the peopling of the “roof of the world” and the antiquity of human high-altitude occupations more generally.
Journal Article
Modulating p38 MAPK signaling by proteostasis mechanisms supports tissue integrity during growth and aging
The conserved p38 MAPK family is activated by phosphorylation during stress responses and inactivated by phosphatases.
C. elegans
PMK-1 p38 MAPK initiates innate immune responses and blocks development when hyperactivated. Here we show that PMK-1 signaling is enhanced during early aging by modulating the stoichiometry of non-phospho-PMK-1 to promote tissue integrity and longevity. Loss of
pmk-1
function accelerates progressive declines in neuronal integrity and lysosome function compromising longevity which has both cell autonomous and cell non-autonomous contributions. CED-3 caspase cleavage limits phosphorylated PMK-1. Enhancing p38 signaling with caspase cleavage-resistant PMK-1 protects lysosomal and neuronal integrity extending a youthful phase. PMK-1 works through a complex transcriptional program to regulate lysosome formation. During early aging, the absolute phospho-p38 amount is maintained but the reservoir of non-phospho-p38 diminishes to enhance signaling without hyperactivation. Our findings show that modulating the stoichiometry of non-phospho-p38 dynamically supports tissue-homeostasis during aging without hyper-activation of stress response.
The extent of phosphorylated p38 MAPK is known to determine signaling. Here, the authors show the relative pool of non-phosphorylated p38 MAPK modulates signaling output to control growth, lysosome formation and neuronal integrity during early aging.
Journal Article
Xeroderma pigmentosum protein XPD controls caspase-mediated stress responses
Caspases regulate and execute a spectrum of functions including cell deaths, non-apoptotic developmental functions, and stress responses. Despite these disparate roles, the same core cell-death machinery is required to enzymatically activate caspase proteolytic activities. Thus, it remains enigmatic how distinct caspase functions are differentially regulated. In this study, we show that Xeroderma pigmentosum protein XPD has a conserved function in activating the expression of stress-responsive caspases in
C. elegans
and human cells without triggering cell death. Using
C. elegans
, we show XPD-1-dependent activation of CED-3 caspase promotes survival upon genotoxic UV irradiation and inversely suppresses responses to non-genotoxic insults such as ER and osmotic stressors. Unlike the TFDP ortholog DPL-1 which is required for developmental apoptosis in
C. elegans
, XPD-1 only activates stress-responsive functions of caspase. This tradeoff balancing responses to genotoxic and non-genotoxic stress may explain the seemingly contradictory nature of caspase-mediated stress resilience versus sensitivity under different stressors.
How caspases are differentially regulated in non-apoptotic stress responses remains enigmatic. Here, the authors show that Xeroderma pigmentosum protein XPD promotes stress specific caspase expression to balance genotoxic and non-genotoxic responses.
Journal Article
Observation of universal strong orbital-dependent correlation effects in iron chalcogenides
Establishing the appropriate theoretical framework for unconventional superconductivity in the iron-based materials requires correct understanding of both the electron correlation strength and the role of Fermi surfaces. This fundamental issue becomes especially relevant with the discovery of the iron chalcogenide superconductors. Here, we use angle-resolved photoemission spectroscopy to measure three representative iron chalcogenides, FeTe
0.56
Se
0.44
, monolayer FeSe grown on SrTiO
3
and K
0.76
Fe
1.72
Se
2
. We show that these superconductors are all strongly correlated, with an orbital-selective strong renormalization in the
d
xy
bands despite having drastically different Fermi surface topologies. Furthermore, raising temperature brings all three compounds from a metallic state to a phase where the
d
xy
orbital loses all spectral weight while other orbitals remain itinerant. These observations establish that iron chalcogenides display universal orbital-selective strong correlations that are insensitive to the Fermi surface topology, and are close to an orbital-selective Mott phase, hence placing strong constraints for theoretical understanding of iron-based superconductors.
A proper theoretical description for unconventional superconductivity in iron-based compounds remains elusive. Here, the authors, to capture the electron correlation strength and the role of Fermi surfaces, report ARPES measurements of three iron chalcogenide superconductors to establish universal features.
Journal Article