Macroscopic effects of the spectral structure in turbulent flows

Two aspects of turbulent flows have been the subject of extensive, split research efforts: macroscopic properties, such as the frictional drag experienced by a flow past a wall, and the turbulent spectrum. The turbulent spectrum may be said to represent the fabric of a turbulent state; in practice it is a power law of exponent \alpha (the "spectral exponent") that gives the revolving velocity of a turbulent fluctuation (or "eddy") of size s as a function of s. The link, if any, between macroscopic properties and the turbulent spectrum remains missing. Might it be found by contrasting the frictional drag in flows with differing types of spectra? Here we perform unprecedented measurements of the frictional drag in soap-film flows, where the spectral exponent \alpha = 3 and compare the results with the frictional drag in pipe flows, where the spectral exponent \alpha = 5/3. For moderate values of the Reynolds number Re (a measure of the strength of the turbulence), we find that in soap-film flows the frictional drag scales as Re^{-1/2}, whereas in pipe flows the frictional drag scales as Re^{-1/4} . Each of these scalings may be predicted from the attendant value of \alpha by using a new theory, in which the frictional drag is explicitly linked to the turbulent spectrum. Our work indicates that in turbulence, as in continuous phase transitions, macroscopic properties are governed by the spectral structure of the fluctuations.Comment: 6 pages, 3 figure

Random Hyper-parameter Search-Based Deep Neural Network for Power Consumption Forecasting

In this paper, we introduce a deep learning approach, based on feed-forward neural networks, for big data time series forecasting with arbitrary prediction horizons. We firstly propose a random search to tune the multiple hyper-parameters involved in the method perfor-mance. There is a twofold objective for this search: firstly, to improve the forecasts and, secondly, to decrease the learning time. Next, we pro-pose a procedure based on moving averages to smooth the predictions obtained by the different models considered for each value of the pre-diction horizon. We conduct a comprehensive evaluation using a real-world dataset composed of electricity consumption in Spain, evaluating accuracy and comparing the performance of the proposed deep learning with a grid search and a random search without applying smoothing. Reported results show that a random search produces competitive accu-racy results generating a smaller number of models, and the smoothing process reduces the forecasting error.Ministerio de Economía y Competitividad TIN2017-88209-C2-1-

Comparison of the Two Followup Observation Strategies for Gravitational Microlensing Planet Searches

There are two different strategies of followup observations for the detection of planets by using microlensing. One is detecting the light curve anomalies affected by the planetary caustic from continuous monitoring of all events detected by microlensing survey programs (type I strategy) and the other is detecting anomalies near the peak amplification affected by the central caustic from intensive monitoring of high amplification events (type II strategy). It was shown by Griest & Safizadeh that the type II strategy yields high planet detection efficiency per event. However, it is not known the planet detection rate by this strategy can make up a substantial fraction of the total rate. In this paper, we estimate the relative planet detection rates expected under the two followup observation strategies. From this estimation, we find that the rate under the type II strategy is substantial and will comprise $\sim 1/4$ -- 1/2 of the total rate. We also find that compared to the type I strategy the type II strategy is more efficient in detecting planets located outside of the lensing zone. We determine the optimal monitoring frequency of the type II strategy to be $\sim 20$ times/night, which can be easily achieved by the current microlensing followup programs even with a single telescope.Comment: total 5 pages, including 3 figures and 1 table, ApJ, submitte

T-cell cytotoxicity in the absence of viral protein synthesis in target cells

CYTOTOXIC T cells lyse only those virus infected target cells in vitro which express, in addition to the viral antigen(s), those K or D region products of the major histocompati-bility complex (MHC) which were present during anti-viral sensitisation in vivo. This 'associative recogniton' by cytotoxic T cells could reflect the interaction of two T-cell receptors with specificity for target K or D gene products and independently for the viral antigen, or one receptor with specificity for virally altered K or D region products (see ref. 1 and refs therein). There are various ways that the MHC antigens could be altered, including 'modification from within', where the virus modifies host protein synthesis by interfering with transcription2, translation or post-translational glycosylation; or 'modification from without' where enzymic or chemical alteration of cell membrane proteins are induced by virus activity at the cell surface. In this report we show that inactivated Sendai virus or isolated Sendai virus envelopes can serve to modify a cell and make it a specific target for Sendai-immune T-cell killing, thus excluding the possibility of 'modification from within' in this system

Anomalous field-dependent specific heat in charge-ordered Pr1−x_{1-x}Cax_xMnO3_3 and La0.5_{0.5}Ca0.5_{0.5}MnO3_3

We report low temperature specific heat measurements of Pr$_{1-x}$Ca$_{x}$MnO$_{3}$ ($0.3\leq x \leq 0.5$) and La$_{0.5}$Ca$_{0.5}$MnO$_{3}$ with and without applied magnetic field. An excess specific heat, $C^{\prime}(T)$, of non-magnetic origin associated with charge ordering is found for all the samples. A magnetic field sufficient to induce the transition from the charge-ordered state to the ferromagnetic metallic state does not completely remove the $C^{\prime}$ contribution. This suggests that the charge ordering is not completely destroyed by a "melting" magnetic field. In addition, the specific heat of the Pr$_{1-x}$Ca$_{x}$MnO$_{3}$ compounds exhibit a large contribution linear in temperature ($\gamma T$) originating from magnetic and charge disorder.Comment: submitted to PRL 5 pages, 3 figures include

Hadronic production of light color-triplet Higgs bosons: an alternative signature for GUT

The conventional signature for grand unified theories (GUT) is the proton decay. Recently, some models in extra dimensions or with specific discrete symmetries, which aim at solving the doublet-triplet problem, allow the color-triplet in the TeV mass region by suppressing the Yukawa couplings of the triplets to matter fermions. We study the hadronic production and detection of these TeV colored Higgs bosons as an alternative signature for GUT, which would behave like massive stable charged particles in particle detectors producing a striking signature of a charged track in the central tracking system and being ionized in the outer muon chamber. We found that the LHC is sensitive to a colored Higgs boson up to about 1.5 TeV. If the color-triplets are stable in cosmological time scale, they may constitute an interesting fraction of the dark matter.Comment: We added the description of a model by Goldberger et al.-- a 5D SU(5) SUSY model in a slice of AdS space with special boundary conditions to suppress proton decay. The color-triplet also has a TeV mas