Neptune's resonances in the Scattered Disk

The Scattered Disk Objects (SDOs) are thought to be a small fraction of the ancient population of leftover planetesimals in the outer solar system that were gravitationally scattered by the giant planets and have managed to survive primarily by capture and sticking in Neptune's exterior mean motion resonances (MMRs). In order to advance understanding of the role of MMRs in the dynamics of the SDOs, we investigate the phase space structure of a large number of Neptune's MMRs in the semi-major axis range 33--140~au by use of Poincar\'e sections of the circular planar restricted three body model for the full range of particle eccentricity pertinent to SDOs. We find that, for eccentricities corresponding to perihelion distances near Neptune's orbit, distant MMRs have stable regions with widths that are surprisingly large and of similar size to those of the closer-in MMRs. We identify a phase-shifted second resonance zone that exists in the phase space at planet-crossing eccentricities but not at lower eccentricities; this second resonance zone plays an important role in the dynamics of SDOs in lengthening their dynamical lifetimes. Our non-perturbative measurements of the sizes of the stable resonance zones confirm previous results and provide an additional explanation for the prominence of the $N$:1 sequence of MMRs over the $N$:2, $N$:3 sequences and other MMRs in the population statistics of SDOs; our results also provide a tool to more easily identify resonant objects.Comment: 20 pages, 15 figures, 1 table. Some re-organization and minor revisions; to be published in CMD

Ellsberg Paradox and Second-order Preference Theories on Ambiguity: Some New Experimental Evidence

We study the two-color problem by Ellsberg (1961) with the modification that the decision maker draws twice with replacement and a different color wins in each draw. The 50-50 risky urn turns out to have the highest risk conceivable among all prospects including the ambiguous one, while all feasible color distributions are mean-preserving spreads to one another. We show that the well-known second-order sophisticated theories like MEU, CEU, and REU as well as Savage’s first-order theory of SEU share the same predictions in our design, for any first-order risk attitude. Yet, we observe that substantial numbers of subjects violate the theory predictions even in this simple design

Ellsberg Paradox and Second-order Preference Theories on Ambiguity: Some New Experimental Evidence

We study the two-color problem by Ellsberg (1961) with the modification that the decision maker draws twice with replacement and a different color wins in each draw. The 50-50 risky urn turns out to have the highest risk conceivable among all prospects including the ambiguous one, while all feasible color distributions are mean-preserving spreads to one another. We show that the well-known second-order sophisticated theories like MEU, CEU, and REU as well as Savage’s first-order theory of SEU share the same predictions in our design, for any first-order risk attitude. Yet, we observe that substantial numbers of subjects violate the theory predictions even in this simple design.Ellsberg paradox, Ambiguity, Second-order risk, Second-order preference theory, Experiment

HOW TO DRIVE EMBRYONIC STEM CELLS TOWARD A RETINAL FATE: THE ROLE OF THE NEURAL INDUCER NOGGIN

Millions of people worldwide suffer of irreversible vision loss because of retinal degenerative diseases such as Retinitis pigmentosa (RP). Embryonic stem cells (ESCs) have been considered as an important source for the replacement of the retinal neurons following degeneration since they have the ability to differentiate into any cell type of the organism. The animal cap tissue of the blastula stage Xenopus embryo consists of a few layers of ectodermal cells, which are pluripotent and can, as ESCs, be induced to form any cell type. Noggin, a small secreted protein, can induce ectoderm to form neural tissue. In this study, we explored the potential of noggin to drive pluripotent Xenopus animal cap embryonic stem (ACES) cells toward retinal cell fates. Using RT-PCR, in situ hybridization and immunohistochemistry, we found that different doses of noggin have different effects on the expression, in cultured ACES cells, of terminal differentiation markers of specific retinal cell types. ACES cells expressing high doses of noggin efficiently induce the expression of retinal differentiation markers, and, following in vivo transplantation, form a retina both in the presumptive eye field and in ectopic posterior regions. The eyes originating from the transplants in the eye field region are functionally equivalent to normal eyes, as revealed by electrophysiology and c-fos expression in response to light. By contrast, ACES cells expressing low doses of noggin induce retina formation only in a low percentage of cases. Our studies show that in Xenopus embryos, appropriate doses of noggin, can effectively drive ACES cells toward retinal cell differentiation. Moreover, we performed microarray analysis to identify the factors necessary for Noggin-mediated retinal induction. The preliminary results we have show the involvement of other signaling pathways that act synergistically with noggin to promote retinal differentiation of ACES cells. This provides a link between BMP and other signaling pathways in eye specification. The further elucidation of the pathways through which Noggin elicits retinal fates will help us to establish improved protocols for the differentiation of mammalian ESCs toward retinal neurons

LOMARC: Look ahead matchmaking for multi-resource coscheduling.

Hyper-Threading (HT) provides a new possibility for job coscheduling without context switch and without the cost for coordinating processes of one parallel job. However, HT achieves high processor throughput at the expense of reducing the performance of the individual process. Since the hardware resources are actually shared between two coscheduled jobs, the resource contention will harm the performance of each job. Most scheduling approaches only focus on the CPU without considering the impact on other resources. In this thesis we present LOMARC, a space-time sharing approach that takes multiple resources, including CPU, I/O, memory and network, into consideration for job coscheduling on HT processors. To improve resource utilization and reduce job response times, LOMARC matches two jobs with complementary resource requirements to coschedule. Our approach partially reorders the waiting job queue by lookahead to increase the possibility of finding a good match. LOMARC also generalizes for standard CPUs, using an adjusted matching scheme and only focusing on hiding I/O latency. In addition, LOMARC incorporates standard scheduling approaches such as priority ordering, aging and backfilling. In our simulation experiment, we use a realistic workload model to provide the convincing results. Our experimental results demonstrate that LOMARC delivers better performance than the standard space sharing approach and the other two job coscheduling approaches for HT processors. The performance gain is mainly due to an increased possibility of coscheduling two complementary jobs by looking ahead on the waiting queue. Source: Masters Abstracts International, Volume: 43-01, page: 0239. Adviser: Angela Sodan. Thesis (M.Sc.)--University of Windsor (Canada), 2004

New Identity, New Mission: A Survey on Contemporary Migrant Workers in Beijing

Ever since the middle and late 1980s, migrant workers have started to move and work in Beijing. Compared with the old generation of migrant workers, the average age of contemporary migrant workers in Beijing is 30.71 and they are inclined to decent jobs with comparatively high education. Migrant workers with high school or above diploma account for 82.5 of the total population. More significantly, having got rid of country culture, the contemporary migrant workers have created new culture

Improved Subsampled Randomized Hadamard Transform for Linear SVM

Subsampled Randomized Hadamard Transform (SRHT), a popular random projection method that can efficiently project a $d$-dimensional data into $r$-dimensional space ($r \ll d$) in $O(dlog(d))$ time, has been widely used to address the challenge of high-dimensionality in machine learning. SRHT works by rotating the input data matrix $\mathbf{X} \in \mathbb{R}^{n \times d}$ by Randomized Walsh-Hadamard Transform followed with a subsequent uniform column sampling on the rotated matrix. Despite the advantages of SRHT, one limitation of SRHT is that it generates the new low-dimensional embedding without considering any specific properties of a given dataset. Therefore, this data-independent random projection method may result in inferior and unstable performance when used for a particular machine learning task, e.g., classification. To overcome this limitation, we analyze the effect of using SRHT for random projection in the context of linear SVM classification. Based on our analysis, we propose importance sampling and deterministic top-$r$ sampling to produce effective low-dimensional embedding instead of uniform sampling SRHT. In addition, we also proposed a new supervised non-uniform sampling method. Our experimental results have demonstrated that our proposed methods can achieve higher classification accuracies than SRHT and other random projection methods on six real-life datasets.Comment: AAAI-2