Some examples related to knot sliceness

It is known that the linking form on the 2-cover of slice knots has a metabolizer. We show that several weaker conditions, or some other conditions related to sliceness, do not imply the existence of a metabolizer. We then show how the Rudolph-Bennequin inequality can be used indirectly to prove that some knots are not slice.Comment: 16 pages, 4 figures; Rev 12 Aug 06: minor corrections (Fig 1,3 and Example 3.7) and expanded introductio

Integrated photonic delay-lasers for reservoir computing

Currently, multiple photonic reservoir computing systems show great promise for providing a practical yet powerful hardware substrate for neuromorphic computing. Among those, delay-based systems offer a simple technological route to implement photonic neuromorphic computation. Its operation boils down to a time-multiplexing with the delay length limiting the processing speed. As most optical setups end up to be bulky employing long fiber loops or free-space optics, the processing speeds are ranging from kSa/s to tens of MSa/s. Therefore, we focus on external cavities which are far shorter than what has been realized before in such experiments. We present experimental results of reservoir computing based on a semiconductor laser, operating in a single mode regime around 1550nm, with a 10.8cm delay line. Both are integrated on an active/passive InP photonic chip built on the Jeppix platform. Using 23 virtual nodes spaced 50 ps apart in the integrated delay section, we increase the processing speed to 0.87GSa/s. The computational performance is benchmarked on a forecasting task applied to chaotic time samples. Competitive performance is observed for injection currents above threshold, with higher pumps having lower prediction errors. The feedback strength can be controlled by electrically pumping integrated amplifiers within the delay section. Nevertheless, we find good performance even when these amplifiers are unpumped. To proof the relevance and necessity of the external cavity on the computational capacity, we have analysed linear and nonlinear memory tasks. We also propose several post-processing methods, which increase the performance without a penalty to speed

Health Care Provider Choice

In order to achieve an ‘optimal health system’ health policies should not only be focused on the supply of health care, but also take cognisance of the demand for health care. Studies of health care demand in South Africa are scarce due to considerable data limitations. This analysis attempts to fill this gap by combining two data sets (specifically, the GHS 2004 and IES/LFS 2000) in order to be able to utilize the wealth of information regarding health care utilization in the General Household Survey. The aim is to inform and encourage debate on how to incorporate demand side considerations in order to arrive at improved public health care in South Africa.health care, demand for health, combining data sets, South Africa

The Online Data Quality Monitoring System at BESIII

The online Data Quality Monitoring (DQM) plays an important role in the data taking process of HEP experiments. BESIII DQM samples data from online data flow, reconstructs them with offline reconstruction software, and automatically analyzes the reconstructed data with user-defined algorithms. The DQM software is a scalable distributed system. The monitored results are gathered and displayed in various formats, which provides the shifter with current run information that can be used to find problems early. This paper gives an overview of DQM system at BESIII.Comment: Already submit to Chinese Physics

Improved Low-qubit Hidden Shift Algorithms

Hidden shift problems are relevant to assess the quantum security of various cryptographic constructs. Multiple quantum subexponential time algorithms have been proposed. In this paper, we propose some improvements on a polynomial quantum memory algorithm proposed by Childs, Jao and Soukharev in 2010. We use subset-sum algorithms to significantly reduce its complexity. We also propose new tradeoffs between quantum queries, classical time and classical memory to solve this problem

A non-equilibrium Monte Carlo approach to potential refinement in inverse problems

The inverse problem for a disordered system involves determining the interparticle interaction parameters consistent with a given set of experimental data. Recently, Rutledge has shown (Phys. Rev. E63, 021111 (2001)) that such problems can be generally expressed in terms of a grand canonical ensemble of polydisperse particles. Within this framework, one identifies a polydisperse attribute (`pseudo-species') $\sigma$ corresponding to some appropriate generalized coordinate of the system to hand. Associated with this attribute is a composition distribution $\bar\rho(\sigma)$ measuring the number of particles of each species. Its form is controlled by a conjugate chemical potential distribution $\mu(\sigma)$ which plays the role of the requisite interparticle interaction potential. Simulation approaches to the inverse problem involve determining the form of $\mu(\sigma)$ for which $\bar\rho(\sigma)$ matches the available experimental data. The difficulty in doing so is that $\mu(\sigma)$ is (in general) an unknown {\em functional} of $\bar\rho(\sigma)$ and must therefore be found by iteration. At high particle densities and for high degrees of polydispersity, strong cross coupling between $\mu(\sigma)$ and $\bar\rho(\sigma)$ renders this process computationally problematic and laborious. Here we describe an efficient and robust {\em non-equilibrium} simulation scheme for finding the equilibrium form of $\mu[\bar\rho(\sigma)]$. The utility of the method is demonstrated by calculating the chemical potential distribution conjugate to a specific log-normal distribution of particle sizes in a polydisperse fluid.Comment: 6 pages, 3 figure

On the Renminbi: The Choice between Adjustment under a Fixed Exchange Rate and Adjustment under a Flexible Rate

Fixed and flexible exchange rates each have advantages, and a country has the right to choose the regime suited to its circumstances. Nevertheless, several arguments support the view that the de facto dollar peg may now have outlived its usefulness for China. (1) China's economy is on the overheating side of internal balance, and appreciation would help easy inflationary pressure. (2) Although foreign exchange reserves are a useful shield against currency crises, by now China's current level is fully adequate, and US treasury securities do not pay a high return. (3) It becomes increasingly difficult to sterilize the inflow over time, exacerbating inflation. (4) Although external balance could be achieved by expenditure reduction, e.g., by raising interest rates, the existence of two policy goals (external balance and internal balance) in general requires the use of two independent policy instruments (e.g., the real exchange rate and the interest rate). (5) A large economy like China can achieve adjustment in the real exchange rate via flexibility in the nominal exchange rate more easily than via price flexibility. (6) The experience of other emerging markets points toward exiting from a peg when times are good and the currency is strong, rather than waiting until times are bad and the currency is under attack. (7) From a longer-run perspective, prices of goods and services in China are low -- not just low relative to the United States (.23), but also low by the standards of a Balassa-Samuelson relationship estimated across countries (which predicts .36). In this specific sense, the yuan was undervalued by approximately 35% in 2000, and is by at least as much today. The paper finds that, typically across countries, such gaps are corrected halfway, on average, over the subsequent decade. These seven arguments for increased exchange rate flexibility need not imply a free float. China is a good counter-example to the popular "corners hypothesis" prohibition on intermediate exchange rate regimes.

Symmetry Breaking in a Model for Nodal Cilia

Nodal cilia are very short cilia found in the embryonic node on the ventral surface of early mammalian embryos. They create a right to left fluid flow that is responsible for determining the normal asymmetry of the internal organs of the mammalian body. To do this, the distal end of the cilium must circle in a counterclockwise sense. Computer simulations with 3-dimensional models of flagella allow examination of 3-dimensional movements such as those of nodal cilia. 3-dimensional circling motions of short cilia can be achieved with velocity controlled models, in which dynein activity is regulated by sliding velocity. If dyneins on one outer doublet are controlled by the sliding velocity experienced by that doublet, the system is symmetric, and the 3-dimensional models can show either clockwise or counterclockwise circling. My computer simulations have examined two possible symmetry breaking mechanisms: 1) dyneins on doublet N are regulated by a mixture of the sliding velocities experienced by doublets N and N+1 (numbered in a clockwise direction, looking from the base). or 2) symmetry is broken by an off-axis force that produces a right-handed twist of the axoneme, consistent with observations that some dyneins can rotate their substrate microtubules in a clockwise direction