1,689 research outputs found
Transformation
Prior to leaving for Claremont Colleges’ Envriolab Asia trip to Malaysia and Singapore, I was conflicted by the question: Do we have the moral authority to interfere with resource extraction and oil-palm development in SE Asia? At that time, the trip seemed imperialistic. Why should people from Malaysia, Indonesia or any developing SE Asia country listen to a group of liberal arts college faculty from a city where widespread habitat modifications have led to significant loss of native habitats, declines in biodiversity, and changes in how these ecosystems function? Many observations transformed my opinion and have inspired me to advocate for transformative environmental and social change both in SE Asia and at home
Transformation
Prior to leaving for Claremont Colleges’ Envriolab Asia trip to Malaysia and Singapore, I was conflicted by the question: Do we have the moral authority to interfere with resource extraction and oil-palm development in SE Asia? At that time, the trip seemed imperialistic. Why should people from Malaysia, Indonesia or any developing SE Asia country listen to a group of liberal arts college faculty from a city where widespread habitat modifications have led to significant loss of native habitats, declines in biodiversity, and changes in how these ecosystems function? Many observations transformed my opinion and have inspired me to advocate for transformative environmental and social change both in SE Asia and at home
Re-envisioning Sustainable Oil-Palm in SE Asia
In Southeast Asia, expansion of oil-palm agriculture, in combination with other industries (logging, fiber, and mega-dams), is transforming significant portions of the landscape threatening biodiversity, key ecosystem services, and human cultural diversity. While transformative answers to these multifaceted environmental issues seem daunting, the conservation biology literature provides a road map for effective techniques to mitigate environmental degradation while allowing for thoughtful, well-planned economic growth. I suggest that the lack of strict operational definitions and a holistic approach to sustainability are the two most critical factors hindering development of sustainable oil-palm agriculture. The task for environmental practitioners is to succinctly define quantifiable long-term sustainability practices and persuade governments and industries that it is in their best interest not to dismiss environmental concerns. If adopted, oil-palm and other industries in SE Asia could become a sustainable model for the world by preserving diverse biological and human communities while expanding economic interests
Near-infrared spectra of ISO selected Chamaeleon I young stellar objects
We present 0.95--2.5 micron moderate (R = 500) resolution spectra of 19
ISOCAM detected sources in the Chamaeleon I dark cloud. Thirteen of these stars
are candidate very low mass members of the cloud proposed by Persi et al. (2000
A&A 357:219) on basis of the mid-IR color excess. The sample also includes a
bona-fide young brown dwarf (Cha Halpha 1), a transition
--stellar/sub-stellar-- object (Cha Halpha 2), one previously known T Tauri
star (Sz 33) and three ISOCAM sources with no mid-IR excess. The spectra of the
mid-IR color excess sources are relatively flat and featureless in this
wavelength range. Both atomic and molecular lines (when in absorption) are
partially veiled suggesting the presence of continuum emission from
circumstellar dust. In addition some of the sources show Paschen and Brackett
lines in emission. We apply the 2 micron water vapor index defined by Wilking
et al. (1999 AJ 117:469) to estimate spectral types. These stars have spectral
types M0--8. We use Persi et al.'s stellar luminosity determinations, in
combination with D'Antona & Mazzitelli latest pre-main sequence evolutionary
tracks, to estimate masses and ages. The ISOCAM detected mid-IR excess sources
have sub-solar masses down to the H-burning limit and a median age of few x
10^6 yr, in good agreement with the higher mass members of this cloud.Comment: Preprint in Manuscript format; 30 pages including 10 figure
Hash Functions for Episodic Recognition and Retrieval
Episodic memory systems for artificially intelligent agents must cope with an ever-growing episodic memory store. This paper presents an approach for minimizing the size of the store by using specialized hash functions to convert each memory into a relatively short binary code. A set of desiderata for such hash functions are presented including locale sensitivity and reversibility. The paper then introduces multiple approaches for such functions and compares their effectiveness
Identification of the donor in GRS 1915+105
We report on the results of medium-resolution spectroscopy of GRS 1915+105 in
the H and K band using the 8m VLT at ESO. We clearly identify absorption
bandheads from CO12 and CO13. Together with other features this results in a
classification of the donor as a K-M III star.Comment: 4 pages, Kluwer style, to appear in Astrophys. Space Sci. Rev, Proc.
of 3rd Microquasar workshop, Granada, Sep. 2000, Eds. A.J. Castro-Tirado, J.
Greiner, J.M. Paredes; all proceedings contr. available at
http://www.aip.de/~jcg/granada.htm
Fundamental parameters and infrared excesses of Hipparcos stars
We derive the fundamental parameters (temperature and luminosity) of 107 619
Hipparcos stars and place these stars on a true Hertzsprung-Russell diagram.
This is achieved by comparing BT-Settl model atmospheres to spectral energy
distributions (SEDs) created from Hipparcos, Tycho, SDSS, DENIS, 2MASS, MSX,
AKARI, IRAS and WISE data. We also identify and quantify from these SEDs any
infrared excesses attributable to circumstellar matter. We compare our results
to known types of objects, focussing on the giant branch stars. Giant star dust
production (as traced by infrared excess) is found to start in earnest around
680 Lsun.Comment: 16 pages, 8 figures, accepted MNRA
Graphene as a quantum surface with curvature-strain preserving dynamics
We discuss how the curvature and the strain density of the atomic lattice
generate the quantization of graphene sheets as well as the dynamics of
geometric quasiparticles propagating along the constant curvature/strain
levels. The internal kinetic momentum of Riemannian oriented surface (a vector
field preserving the Gaussian curvature and the area) is determined.Comment: 13p, minor correction
Loss of MITF expression during human embryonic stem cell differentiation disrupts retinal pigment epithelium development and optic vesicle cell proliferation
Microphthalmia-associated transcription factor (MITF) is a master regulator of pigmented cell survival and differentiation with direct transcriptional links to cell cycle, apoptosis and pigmentation. In mouse, Mitf is expressed early and uniformly in optic vesicle (OV) cells as they evaginate from the developing neural tube, and null Mitf mutations result in microphthalmia and pigmentation defects. However, homozygous mutations in MITF have not been identified in humans; therefore, little is known about its role in human retinogenesis. We used a human embryonic stem cell (hESC) model that recapitulates numerous aspects of retinal development, including OV specification and formation of retinal pigment epithelium (RPE) and neural retina progenitor cells (NRPCs), to investigate the earliest roles of MITF. During hESC differentiation toward a retinal lineage, a subset of MITF isoforms was expressed in a sequence and tissue distribution similar to that observed in mice. In addition, we found that promoters for the MITF-A, -D and -H isoforms were directly targeted by Visual Systems Homeobox 2 (VSX2), a transcription factor involved in patterning the OV toward a NRPC fate. We then manipulated MITF RNA and protein levels at early developmental stages and observed decreased expression of eye field transcription factors, reduced early OV cell proliferation and disrupted RPE maturation. This work provides a foundation for investigating MITF and other highly complex, multi-purposed transcription factors in a dynamic human developmental model syste
Prediction of Emerging Technologies Based on Analysis of the U.S. Patent Citation Network
The network of patents connected by citations is an evolving graph, which
provides a representation of the innovation process. A patent citing another
implies that the cited patent reflects a piece of previously existing knowledge
that the citing patent builds upon. A methodology presented here (i) identifies
actual clusters of patents: i.e. technological branches, and (ii) gives
predictions about the temporal changes of the structure of the clusters. A
predictor, called the {citation vector}, is defined for characterizing
technological development to show how a patent cited by other patents belongs
to various industrial fields. The clustering technique adopted is able to
detect the new emerging recombinations, and predicts emerging new technology
clusters. The predictive ability of our new method is illustrated on the
example of USPTO subcategory 11, Agriculture, Food, Textiles. A cluster of
patents is determined based on citation data up to 1991, which shows
significant overlap of the class 442 formed at the beginning of 1997. These new
tools of predictive analytics could support policy decision making processes in
science and technology, and help formulate recommendations for action
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