188,186 research outputs found
Chan An Ancient Maya Farming Community
No full textThe farming community of Chan thrived for over twenty centuries, surpassing the longevity of many larger Maya urban centers. Between 800 BC and 1200 AD it was a major food production center, and this collection of essays reveals the important role played by Maya farmers in the development of ancient Maya society. Chan offers a synthesis of compelling and groundbreaking discoveries gathered over ten years of research at this one archaeological site in Belize. The contributors develop three central themes, which structure the book. They examine how sustainable farming practices maintained the surrounding forest, allowing the community to exist for two millennia. They trace the origins of elite Maya state religion to the complex religious belief system developed in small communities such as Chan. Finally, they describe how the group-focused political strategies employed by local leaders differed from the highly hierarchical strategies of the Classic Maya kings in their large cities. In breadth, methodology, and findings, this volume scales new heights in the study of Maya society and culture.Cover -- Title -- Copyright -- Contents -- List of Figures -- List of Tables -- Foreword -- Acknowledgments -- 1. Introducing the Chan Site: Farmers in Complex Societies -- Part 1. Time, Space, and Landscapes -- 2. A Changing Cultural Landscape: Settlement Survey and GIS at Chan -- 3. Ceramics and Chronology at Chan -- 4. Agricultural Practices at Chan: Farming and Political Economy in an Ancient Maya Community -- 5. Agroforestry and Agricultural Production of the Ancient Maya at Chan -- Part 2. Life in a Farming Community Center -- 6. Ritual in a Farming Community -- 7. Nonroyal Governance at Chan's Community Center -- 8. "Empty" Spaces and Public Places: A Microscopic View of Chan's Late Classic West Plaza -- Part 3. Diversity across the Chan Community -- 9. Recognizing Difference in Small-Scale Settings: An Examination of Social Identity Formation at the Northeast Group, Chan -- 10. Organization of Chert Tool Economy during the Late and Terminal Classic Periods at Chan: Preliminary Thoughts Based upon Debitage Analyses -- 11. Limestone Quarrying and Household Organization at Chan -- Part 4. Bodies, Material Culture, and Meaning -- 12. The Chan Community: A Bioarchaeological Perspective -- 13. Creating Community with Shell -- 14. Obsidian Acquisition, Trade, and Regional Interaction at Chan -- 15. Contextualizing Ritual Behavior: Caches, Burials, and Problematical Deposits from Chan's Community Center -- Part 5. Conclusion -- 16. Learning from an Ancient Maya Farming Community -- References -- List of Contributors -- Index -- A -- B -- C -- D -- E -- F -- G -- H -- I -- J -- K -- L -- M -- N -- O -- P -- Q -- R -- S -- T -- V -- W -- X -- YThe farming community of Chan thrived for over twenty centuries, surpassing the longevity of many larger Maya urban centers. Between 800 BC and 1200 AD it was a major food production center, and this collection of essays reveals the important role played by Maya farmers in the development of ancient Maya society. Chan offers a synthesis of compelling and groundbreaking discoveries gathered over ten years of research at this one archaeological site in Belize. The contributors develop three central themes, which structure the book. They examine how sustainable farming practices maintained the surrounding forest, allowing the community to exist for two millennia. They trace the origins of elite Maya state religion to the complex religious belief system developed in small communities such as Chan. Finally, they describe how the group-focused political strategies employed by local leaders differed from the highly hierarchical strategies of the Classic Maya kings in their large cities. In breadth, methodology, and findings, this volume scales new heights in the study of Maya society and culture.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
LAUREN M. CHAN, JAMES W. ARCHIE, ANNE D. YODER & LEE A. FITZGERALD (2013) Review of the systematic status of Sceloporus arenicolus Degenhardt and Jones, 1972 with an estimate
No full textChan, Lauren M., Archie, James W., Yoder, Anne D., Fitzgerald, Lee A. (2013): LAUREN M. CHAN, JAMES W. ARCHIE, ANNE D. YODER & LEE A. FITZGERALD (2013) Review of the systematic status of Sceloporus arenicolus Degenhardt and Jones, 1972 with an estimate. Zootaxa 3686 (1): 99-100, DOI: 10.11646/zootaxa.3686.1.
Orthogonal Range Searching in Moderate Dimensions: k-d Trees and Range Trees Strike Back
No full textWe revisit the orthogonal range searching problem and the exact l_infinity nearest neighbor searching problem for a static set of n points when the dimension d is moderately large. We give the first data structure with near linear space that achieves truly sublinear query time when the dimension is any constant multiple of log n. Specifically, the preprocessing time and space are O(n^{1+delta}) for any constant delta>0, and the expected query time is n^{1-1/O(c log c)} for d = c log n. The data structure is simple and is based on a new "augmented, randomized, lopsided" variant of k-d trees. It matches (in fact, slightly improves) the performance of previous combinatorial algorithms that work only in the case of offline queries [Impagliazzo, Lovett, Paturi, and Schneider (2014) and Chan (SODA'15)]. It leads to slightly faster combinatorial algorithms for all-pairs shortest paths in general real-weighted graphs and rectangular Boolean matrix multiplication.
In the offline case, we show that the problem can be reduced to the Boolean orthogonal vectors problem and thus admits an n^{2-1/O(log c)}-time non-combinatorial algorithm [Abboud, Williams, and Yu (SODA'15)]. This reduction is also simple and is based on range trees.
Finally, we use a similar approach to obtain a small improvement to Indyk's data structure [FOCS'98] for approximate l_infinity nearest neighbor search when d = c log n
Coulter, Chan L., July 23, 1996 [Interview]
No full textProfessor of Philosophy Chan L. Coulter was interviewed on June 17, 1996, by Michael Birkner and David Hedrick about his career at Gettysburg College, including memorable colleagues, classes, and controversies.Dunn, Seymour B.; Glatfelter, Charles H.; Hanson, C. Arnold; Crapster, Basil L.; Barnes, Robert D.; Baskerville, Edward J.; Mara, Richard T.; Qually, Ingolf; Bugbee, Bruce W.; Richardson, Norman E.; Bolich, Harry F.; Arms, Richard A.; Mason, Francis C.; Taylor, Kathrine Kressmann; Schmidt, Emile O.; Glassick, Charles E.; Potts, David B.Willard S. Paul Years; Carl Arnold Hanson Years; Charles E. Glassick Years; Gordon A. Haaland Year
Differences in Radiative Forcing, Not Sensitivity, Explain Differences in Summertime Land Temperature Variance Change Between CMIP5 and CMIP6
No full text© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Chan, D., Rigden, A., Proctor, J., Chan, P. W., & Huybers, P. Differences in radiative forcing, not sensitivity, explain differences in summertime land temperature variance change between CMIP5 and CMIP6. Earth’s Future, 10(2), (2022): e2021EF002402, https://doi.org/10.1029/2021EF002402.How summertime temperature variability will change with warming has important implications for climate adaptation and mitigation. CMIP5 simulations indicate a compound risk of extreme hot temperatures in western Europe from both warming and increasing temperature variance. CMIP6 simulations, however, indicate only a moderate increase in temperature variance that does not covary with warming. To explore this intergenerational discrepancy in CMIP results, we decompose changes in monthly temperature variance into those arising from changes in sensitivity to forcing and changes in forcing variance. Across models, sensitivity increases with local warming in both CMIP5 and CMIP6 at an average rate of 5.7 ([3.7, 7.9]; 95% c.i.) × 10−3°C per W m−2 per °C warming. We use a simple model of moist surface energetics to explain increased sensitivity as a consequence of greater atmospheric demand (∼70%) and drier soil (∼40%) that is partially offset by the Planck feedback (∼−10%). Conversely, forcing variance is stable in CMIP5 but decreases with warming in CMIP6 at an average rate of −21 ([−28, −15]; 95% c.i.) W2 m−4 per °C warming. We examine scaling relationships with mean cloud fraction and find that mean forcing variance decreases with decreasing cloud fraction at twice the rate in CMIP6 than CMIP5. The stability of CMIP6 temperature variance is, thus, a consequence of offsetting changes in sensitivity and forcing variance. Further work to determine which models and generations of CMIP simulations better represent changes in cloud radiative forcing is important for assessing risks associated with increased temperature variance.This study was supported by the Harvard Global Institute and NSF (Award 1903657). D. Chan was also supported by the Woods Hole Oceanographic Institute Weston Howland Jr. Postdoctoral Fellowship
Chan-Sik Kim
No full text학위논문(박사)--아주대학교 일반대학원 :의학과,2014. 2I. INTRODUCTION 1
A. Age-related oxidative renal injury 1
B. AGEs and oxidative stress 2
C. High mobility group box protein-1 and receptor for AGE 3
D. Role of podocyte in glomerular pathobiology 3
E. Exercise and renal injury 4
F. Korean red ginseng and renal injury 5
G. Obesity-related renal injury 6
H. Aims of study 6
II. MATERIALS AND METHODS 8
A. KRG preparation 8
B. Animals and experimental design 8
C. Analysis of metabolic data 9
D. In vitro assay of the cross-linking of glycated proteins 10
E. Immunohistochemical staining 10
F. Double staining for TUNEL and Wilms tumor antigen-1 11
G. Apoptosis analysis 11
H. Statistical analysis 12
III. Results 13
A. Body weight and blood lipid profile 13
B. CML accumulation in renal tissues 16
C. Oxidative DNA damage in renal tissues 18
D. Apoptosis assay in renal tissues 20
E. Expression of Bax and Bcl-2 in renal tissues 22
F. Caspase-3 activation 25
G. Glomerular podocyte loss 27
H. Inhibitory effect of KRG on glycated proteins cross-linking in vitro. 31
I. Body weight and blood lipid profile 33
J. Oxidative DNA damage in renal tissues 36
K. Protein glycations in renal tissues 38
L. Apoptosis assay in renal tissues 40
M. HMGB1 cytoplasmic translocalization in renal tissues 42
N. RAGE Expression in renal tissues 44
IV. DISCUSSION 47
V. CONCLUSION 53
VI. REFERENCES 54
국문요약 67MasterA decline in renal function is seen commonly in aging. Aging further increase oxidative stress in the kidney and are associated with reduced renal function. Aging is progressive accumulation of oxidative agents. Advanced glycation end products (AGEs) and advanced lipoxidation end products (ALEs) formation has been implicated in the aging process. Obesity induced by a high-fat diet (HFD) may reduce renal function. However, the impact of obese on the age-related renal disease is not well understood. Exercise reduces oxidative stress. Korean red ginseng (KRG) has been reported to ameliorate oxidative tissue injury and has an anti-aging effect. The purpose of this study was to investigate whether HFD would accelerate ᴅ-galactose (GAL)-induced renal injury and to examine the preventive effects of a regular exercise and KRG on GAL/HFD -induced renal injury.
In the first experiment, age-related renal injury was induced by an administration with GAL (100 mg/kg, i.p.) in the absence or presence of high-fat diet (60% kcal as fat) for 9 weeks. The exercise group was trained on a motorized treadmill for 60 min/day, 5 times/week over the same period. In the second experiment, in vitro inhibitory effect of KRG on AGEs-cross-linking was examined by enzyme-linked immunosorbent assay (ELISA), and KRG (200 mg/kg/day) was given to GAL plus HFD-induced aging rats for 9 weeks.
Immunohistochemical staining for 8-OHdG (a specific marker of oxidative DNA damage) and CMLs (a marker of both glycation and lipoxidation reactions) revealed that GAL-treated rats fed a HFD showed aggravated renal injury associated with more pronounced renal AGEs/ALEs formation and oxidative DNA damage. In TUNEL assay, the numbers of TUNEL-positive cell in the GAL/HFD group were significantly higher than the GAL group. The expression of activated caspase-3 protein and Bax/Bcl-2 ratio also were significantly increased in the GAL/HFD group than that in the GAL group. Moreover, imuunohistochemical staining for synaptopodin and WT-1, well-known podocyte markers, revealed that HFD aggravates the loss of podocytes in renal glomeruli. However, the regular exercise restored all these renal changes in HFD plus GAL-treated rats.
KRG inhibited AGEs and collagen cross-link at ten-fold less concentration (IC50=55.65 μg/ml) than aminoguanidine (IC50=563.54 μg/ml), a well-known glycation inhibitor. When rats were fed with a HFD for 9 weeks in GAL-induced aging rats, renal AGEs accumulation, extracellular high mobility group box 1 protein (HMGB1), a signal of tissue damage) and receptor for AGE (RAGE) were extensively expressed in renal tissues of the GAL/HFD group than that in the GAL group. HMGB1 was clearly translocated from the nucleus to the cytoplasm in renal tubular epithelial cells. However, treatment of HFD plus GAL-induced aging rats with KRG restored all these renal changes.
In summary, when rats were fed with a HFD for 9 weeks in GAL-induced aging rats, oxidative DNA damage, protein glycations, renal cell apoptosis and cytoplasmic translocation of HMGB1 were caused in renal glomerular cells and tubular epithelial cells. However, the regular exercise and KRG treatment restored all these renal changes in GAL/HFD-treated rats. Therefore, this study suggested that long-term HFD may accelerate the deposition of AGEs/ALEs and oxidative renal injury in GAL-treated rats. This HFD-increased renal injury in GAL-induced aging rats could be suppressed by regular exercise and KRG through the repression of oxidative injury
D-brane Chan-Paton Factors and Orientifolds
No full textIn this thesis, we mainly study the structure of -brane Chan-Paton factors in Type II orientifold theories. An explicit structure is found through a thorough and systematic derivation. For this purpose, we give a complete analysis of the
worldsheet parity square action for all p-q open strings (i.e, the strings starting from -branes and ending on -branes),
which is an extension of Gimon-Polchinski's work on the parity square action for p-q strings with even. We also formulate the rules for computing the scattering amplitudes of open strings ending on D-branes. These are important to build phenomenological models in string theory. As an application to the mathematical aspects of
string theory, we confirm the proposal that the D-brane charges in Type II orientifolds are classified by the KR-theory groups. All
these results will appear in our paper\footnote{Dongfeng Gao and Kentaro Hori, Clifford Algebras and Chan-Paton Factors, to appear.}.
We also show some preliminary results on the B-type D-branes in the orientifolds of linear sigma models. A typical linear sigma model has both a geometric phase and a Landau-Ginzberg phase over its
K\"ahler moduli space. The B-type D-branes are described by suitable categories in a linear sigma model and its phases. The orientifold projection induces parity mappings on the various categories. By
looking at the transportation of invariant branes in the moduli space, we find the relations among the parity mappings of different phases in the quintic model.Ph
Naruse, T., Chan, T.-Y., Tan H.H., Ahyong, S.T. & Reimer, J.D. (2012) Scientific Results of the Marine Biodiversity Expedition-KUMEJIMA 2009. Zootaxa, 3367, 1-280.
No full textNARUSE, T., CHAN, T. Y., TAN, H. H., AHYONG, S. T., REIMER, J. D. (2012): Naruse, T., Chan, T.-Y., Tan H.H., Ahyong, S.T. & Reimer, J.D. (2012) Scientific Results of the Marine Biodiversity Expedition-KUMEJIMA 2009. Zootaxa, 3367, 1-280. Zootaxa 3390 (1): 68, DOI: 10.11646/zootaxa.3390.1.7, URL: http://dx.doi.org/10.11646/zootaxa.3390.1.
Helical structure of the waves propagating in a spinning Timoshenko beam
No full textThe aim of the paper is to study the cause of a frequency-splitting phenomenon that occurs in a spinning Timoshenko beam. The associated changes in the structure of the progressive waves are investigated to shed light on the relationship between the wave motion in a spinning beam and the whirling of a shaft. The main result is that travelling bending waves in a beam spinning about its central axis have the topological structure of a revolving helix traced by the centroidal axis with right-handed or left-handed chirality. Each beam element behaves like a gyroscopic disc in precession being rotated at the wave frequency with anticlockwise or clockwise helicity. The gyroscopic effect is identified as the cause of the frequency splitting and is shown to induce a coupling between two interacting travelling waves lying in mutually orthogonal planes. Two revolving waves travelling in the same direction in space appear, one at a higher and one at a lower frequency compared with the pre-split frequency value. With reference to a given spinning speed, taken as clockwise, the higher one revolves clockwise and the lower one has anticlockwise helicity, each wave being represented by a characteristic four-component vector wavefunction.Two factors are identified as important, the shear-deformation factor q and the gyroscopic-coupling phase factor ?. The q-factor is related to the wavenumber and the geometric shape of the helical wave. The ?-factor is related to the wave helicity and has two values, +?/2 and ??/2 corresponding to the anticlockwise and clockwise helicity, respectively. The frequency-splitting phenomenon is addressed by analogy with other physical phenomena such as the Jeffcott whirling shaft and the property of the local energy equality of a travelling wave. The relationship between Euler's formula and the present result relating to the helical properties of the waves is also explored
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
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