Unbounded-error One-way Classical and Quantum Communication Complexity

This paper studies the gap between quantum one-way communication complexity $Q(f)$ and its classical counterpart $C(f)$, under the {\em unbounded-error} setting, i.e., it is enough that the success probability is strictly greater than 1/2. It is proved that for {\em any} (total or partial) Boolean function $f$, $Q(f)=\lceil C(f)/2 \rceil$, i.e., the former is always exactly one half as large as the latter. The result has an application to obtaining (again an exact) bound for the existence of $(m,n,p)$-QRAC which is the $n$-qubit random access coding that can recover any one of $m$ original bits with success probability $\geq p$. We can prove that $(m,n,>1/2)$-QRAC exists if and only if $m\leq 2^{2n}-1$. Previously, only the construction of QRAC using one qubit, the existence of $(O(n),n,>1/2)$-RAC, and the non-existence of $(2^{2n},n,>1/2)$-QRAC were known.Comment: 9 pages. To appear in Proc. ICALP 200

Unbounded-Error Classical and Quantum Communication Complexity

Since the seminal work of Paturi and Simon \cite[FOCS'84 & JCSS'86]{PS86}, the unbounded-error classical communication complexity of a Boolean function has been studied based on the arrangement of points and hyperplanes. Recently, \cite[ICALP'07]{INRY07} found that the unbounded-error {\em quantum} communication complexity in the {\em one-way communication} model can also be investigated using the arrangement, and showed that it is exactly (without a difference of even one qubit) half of the classical one-way communication complexity. In this paper, we extend the arrangement argument to the {\em two-way} and {\em simultaneous message passing} (SMP) models. As a result, we show similarly tight bounds of the unbounded-error two-way/one-way/SMP quantum/classical communication complexities for {\em any} partial/total Boolean function, implying that all of them are equivalent up to a multiplicative constant of four. Moreover, the arrangement argument is also used to show that the gap between {\em weakly} unbounded-error quantum and classical communication complexities is at most a factor of three.Comment: 11 pages. To appear at Proc. ISAAC 200

The Physical Properties of LBGs at z>5: Outflows and the "pre-enrichment problem"

We discuss the properties of Lyman Break galaxies (LBGs) at z>5 as determined from disparate fields covering approximately 500 sq. arcmin. While the broad characteristics of the LBG population has been discussed extensively in the literature, such as luminosity functions and clustering amplitude, we focus on the detailed physical properties of the sources in this large survey (>100 with spectroscopic redshifts). Specifically, we discuss ensemble mass estimates, stellar mass surface densities, core phase space densities, star-formation intensities, characteristics of their stellar populations, etc as obtained from multi-wavelength data (rest-frame UV through optical) for a subsample of these galaxies. In particular, we focus on evidence that these galaxies drive vigorous outflows and speculate that this population may solve the so-called ``pre-enrichment problem''. The general picture that emerges from these studies is that these galaxies, observed about 1 Gyr after the Big Bang, have properties consistent with being the progenitors of the densest stellar systems in the local Universe -- the centers of old bulges and early type galaxies.Comment: 4 pages, to appear in "Pathways Through an Eclectic Universe", J. H. Knappen, T. J. Mahoney, and A. Vazedekis (Eds.), ASP Conf. Ser., 200

Tolerância de tubérculos de Cyperus rotundus, L. sob prolongada submersão em água.

A planta invasora, Cyperus rotundus, L. de habito perene, oferece considerável resistencia para todos os métodos de controle, sejam mecânicos, manuais, ou mesmo químicos, esses, possibilitando restrição ao seu crescimento e aumento de sua população. O controle biológico também não tem tido sucesso. Procura-se no presente relato, demonstrar sua tolerância a submersão, mesmo por períodos necessários para inundação do arroz, quando plantado em várzeas inundáveis. Essa plantação, tem a base das plantas submersas, ate a proximidade da colheita. Em media, isso perdura por 60 dias. Em ensaios conduzidos para testar a tolerância dos tubérculos de C. rotundus, em água e em água barrenta, confirmou-se que, a submersão por período de 119 dias, em qualquer dos meios citados, ainda deixa aproximadamente 10% de tubérculos viáveis, os quais, drenada a área ocupada pelo arroz, tem condições para rebrota e alastramento, sob as condições variáveis. Em um segundo ensaio, mantidos os tubérculos por período de 220 dias submersos, ainda foram viáveis 6% dos tubérculos que foram avaliados. Donde a conclusão, de que, somente por submersão não torna sucesso, o controle da planta invasora de habito perene que e o Cyperus rotundus, L. todavia, a redução obtida na população, já pode ser de utilidade, para a multiplicação, respeitadas com a complementação de outros métodos integrados no processo

Hydrodynamic fluctuations in relativistic superfluids

The Hamiltonian formulation of superfluids based on noncanonical Poisson brackets is studied in detail. The assumption that the momentum density is proportional to the flow of the conserved energy is shown to lead to the covariant relativistic theory previously suggested by Khalatnikov, Lebedev and Carter, and some potentials in this theory are given explicitly. We discuss hydrodynamic fluctuations in the presence of dissipative effects and we derive the corresponding set of hydrodynamic correlation functions. Kubo relations for the transport coefficients are obtained.Comment: 13 pages, no figures, two references adde

Dynamic Structure Factor of Normal Fermi Gas from Collisionless to Hydrodynamic Regime

The dynamic structure factor of a normal Fermi gas is investigated by using the moment method for the Boltzmann equation. We determine the spectral function at finite temperatures over the full range of crossover from the collisionless regime to the hydrodynamic regime. We find that the Brillouin peak in the dynamic structure factor exhibits a smooth crossover from zero to first sound as functions of temperature and interaction strength. The dynamic structure factor obtained using the moment method also exhibits a definite Rayleigh peak ($/omega /sim 0$), which is a characteristic of the hydrodynamic regime. We compare the dynamic structure factor obtained by the moment method with that obtained from the hydrodynamic equations.Comment: 19 pages, 9 figure

Initial breastfeeding attitudes and practices of women born in Turkey, Vietnam and Australia after giving birth in Australia

BACKGROUND: Cultural variations exist in the proportion of women who breastfeed. For some cultural groups, migration to a new country is associated with a reduction in the initiation and duration of breastfeeding. This paper describes the initial breastfeeding attitudes and practices of women born in Vietnam, Turkey and Australia who gave birth in Australia. METHODS: The study included 300 women: 100 hundred Turkish-born, 100 Vietnamese-born and 100 Australian-born women who had given birth in a large public, tertiary referral maternity hospital between January 1998 and May 1999 in Melbourne, Australia. Women were interviewed in hospital, between 24 hours after the birth and discharge from hospital. Data were collected using a structured questionnaire with some open-ended questions. Only women who had a normal vaginal birth and who gave birth to a healthy baby were included in the study. RESULTS: Almost all Turkish women initiated breastfeeding (98%) compared with 84% of Australian women. Vietnamese women had the lowest rate of breastfeeding initiation (75%), perceived their partners to be more negative about breastfeeding and did not value the health benefits of colostrum to the same extent as the other two groups. Forty percent of Vietnamese women gave their baby formula in hospital. The results of this study add to the previously reported finding that immigrant Vietnamese women have low breastfeeding rates compared with other groups. CONCLUSION: Despite the Baby Friendly status of the hospital where the study was conducted, major differences were found in breastfeeding initiation. Future research should develop and test interventions aimed at increasing breastfeeding initiation in Vietnamese women where initiation is low

Self-consistent theory of turbulence

A new approach to the stochastic theory of turbulence is suggested. The coloured noise that is present in the stochastic Navier-Stokes equation is generated from the delta-correlated noise allowing us to avoid the nonlocal field theory as it is the case in the conventional theory. A feed-back mechanism is introduced in order to control the noise intensity.Comment: submitted to J.Tech. Phys.Letters (St. Petersburg

Leading Order Calculation of Shear Viscosity in Hot Quantum Electrodynamics from Diagrammatic Methods

We compute the shear viscosity at leading order in hot Quantum Electrodynamics. Starting from the Kubo relation for shear viscosity, we use diagrammatic methods to write down the appropriate integral equations for bosonic and fermionic effective vertices. We also show how Ward identities can be used to put constraints on these integral equations. One of our main results is an equation relating the kernels of the integral equations with functional derivatives of the full self-energy; it is similar to what is obtained with two-particle-irreducible effective action methods. However, since we use Ward identities as our starting point, gauge invariance is preserved. Using these constraints obtained from Ward identities and also power counting arguments, we select the necessary diagrams that must be resummed at leading order. This includes all non-collinear (corresponding to 2 to 2 scatterings) and collinear (corresponding to 1+N to 2+N collinear scatterings) rungs responsible for the Landau-Pomeranchuk-Migdal effect. We also show the equivalence between our integral equations obtained from quantum field theory and the linearized Boltzmann equations of Arnold, Moore and Yaffe obtained using effective kinetic theory.Comment: 45 pages, 22 figures (note that figures 7 and 14 are downgraded in resolution to keep this submission under 1000kb, zoom to see them correctly

Hydrodynamic approach to coherent nuclear spin transport

We develop a linear response formalism for nuclear spin diffusion in a dipolar coupled solid. The theory applies to the high-temperature, long-wavelength regime studied in the recent experiments of Boutis et al. [Phys. Rev. Lett. 92, 137201 (2004)], which provided direct measurement of interspin energy diffusion in such a system. A systematic expansion of Kubo's formula in the flip-flop term of the Hamiltonian is used to calculate the diffusion coefficients. We show that this approach is equivalent to the method of Lowe and Gade [Phys. Rev. 156, 817 (1967)] and Kaplan [Phys. Rev. B 2, 4578 (1970)], but has several calculational and conceptual advantages. Although the lowest orders in this expansion agree with the experimental results for magnetization diffusion, this is not the case for energy diffusion. Possible reasons for this disparity are suggested.Comment: 7 pages, REVTeX4; Published Versio