Online Learning for Time Series Prediction

In this paper we address the problem of predicting a time series using the ARMA (autoregressive moving average) model, under minimal assumptions on the noise terms. Using regret minimization techniques, we develop effective online learning algorithms for the prediction problem, without assuming that the noise terms are Gaussian, identically distributed or even independent. Furthermore, we show that our algorithm's performances asymptotically approaches the performance of the best ARMA model in hindsight.Comment: 17 pages, 6 figure

Budget-Constrained Item Cold-Start Handling in Collaborative Filtering Recommenders via Optimal Design

It is well known that collaborative filtering (CF) based recommender systems provide better modeling of users and items associated with considerable rating history. The lack of historical ratings results in the user and the item cold-start problems. The latter is the main focus of this work. Most of the current literature addresses this problem by integrating content-based recommendation techniques to model the new item. However, in many cases such content is not available, and the question arises is whether this problem can be mitigated using CF techniques only. We formalize this problem as an optimization problem: given a new item, a pool of available users, and a budget constraint, select which users to assign with the task of rating the new item in order to minimize the prediction error of our model. We show that the objective function is monotone-supermodular, and propose efficient optimal design based algorithms that attain an approximation to its optimum. Our findings are verified by an empirical study using the Netflix dataset, where the proposed algorithms outperform several baselines for the problem at hand.Comment: 11 pages, 2 figure

Reorganization of columnar architecture in the growing visual cortex

Many cortical areas increase in size considerably during postnatal development, progressively displacing neuronal cell bodies from each other. At present, little is known about how cortical growth affects the development of neuronal circuits. Here, in acute and chronic experiments, we study the layout of ocular dominance (OD) columns in cat primary visual cortex (V1) during a period of substantial postnatal growth. We find that despite a considerable size increase of V1, the spacing between columns is largely preserved. In contrast, their spatial arrangement changes systematically over this period. While in young animals columns are more band-like, layouts become more isotropic in mature animals. We propose a novel mechanism of growth-induced reorganization that is based on the `zigzag instability', a dynamical instability observed in several inanimate pattern forming systems. We argue that this mechanism is inherent to a wide class of models for the activity-dependent formation of OD columns. Analyzing one member of this class, the Elastic Network model, we show that this mechanism can account for the preservation of column spacing and the specific mode of reorganization of OD columns that we observe. We conclude that neurons systematically shift their selectivities during normal development and that this reorganization is induced by the cortical expansion during growth. Our work suggests that cortical circuits remain plastic for an extended period in development in order to facilitate the modification of neuronal circuits to adjust for cortical growth.Comment: 8+13 pages, 4+8 figures, paper + supplementary materia

Emergence of Small-World Anatomical Networks in Self-Organizing Clustered Neuronal Cultures

In vitro primary cultures of dissociated invertebrate neurons from locust ganglia are used to experimentally investigate the morphological evolution of assemblies of living neurons, as they self-organize from collections of separated cells into elaborated, clustered, networks. At all the different stages of the culture's development, identification of neurons' and neurites' location by means of a dedicated software allows to ultimately extract an adjacency matrix from each image of the culture. In turn, a systematic statistical analysis of a group of topological observables grants us the possibility of quantifying and tracking the progression of the main network's characteristics during the self-organization process of the culture. Our results point to the existence of a particular state corresponding to a small-world network configuration, in which several relevant graph's micro- and meso-scale properties emerge. Finally, we identify the main physical processes ruling the culture's morphological transformations, and embed them into a simplified growth model qualitatively reproducing the overall set of experimental observations

ANALISA HASIL AUDIT PEMERINTAH TERHADAP TINGKAT KORUPSI PEMERINTAHAN PROVINSI JAWA TENGAH

This research aims to analyze the influence of goverment auditing results such as audit opinion, audit finding, audit retrification on the level of corruption in Central Java Province. This research uses purposive sampling and the research uses secondary data from audit results of State audit board of indonesia (BPK-RI) and data total corruption from Komisi Pemberantasan Korupsi (KPK) and Indonesian Corruption Watch (ICW). The population in this study is all districts and cities in central Java Province.The results of this study showed that audit opinion has negative effect on corruptin level, and that partials audit finding has negative effect and significant on corruption level and audit retrification has positive effect and sifnificant on corruptin level. Simultaneously, these variables have significant influence on corruption level

THE INFLUENCE OF INFLATION, GRDP, AND MSE ON UNEMPLOYMENT RATE IN CENTRAL JAVA PROVINCE 2017-2019

Penelitian bertujuan untuk mengetahui pengaruh inflasi, PDRB dan UMK terhadap tingkat pengangguran di Provinsi Jawa Tengah. Penelitian ini merupakan penelitian kuantitatif. Analisis data dalam penelitian ini menggunakan regresi linear berganda dengan EViews 10. Populasi dalam penelitian ini adalah seluruh kabupaten dan kota di Provinsi Jawa Tengah tahun 2017-2019. Sampel dalam penelitian ini ialah 35 kabupaten dan kota di Provinsi Jawa Tengah. Data yang digunakan dalam penelitian ini ialah data sekunder yang diperoleh dari Badan Pusat Statistik. Hasil penelitian ini menunjukkan bahwa inflasi dan UMK berpengaruh negative dan tidak signifikan terhadap tingkat pengangguran di Provinsi Jawa Tengah. Sedangkan PDRB berpengaruh negative dan signifikan terhadap tingkat pengangguran di Jawa Tengah. Berdasarkan uji F variable inflasi, PDRB dan UMK secara simultan berpengaruh signifikan terhadap tingkat pengangguran di Provinsi Jawa Tengah. Berdasarkan hasil uji koefisien determinasi atau R square diperoleh 0,864915 hal ini menunjukkan bahwa presentase pengaruh variable inflasi, PDRB dan UMK terhadap variable tingkat pengangguran sebesar 86,4%

Pengaruh Profitabilitas Terhadap Harga Saham Pada Jakarta Islamic Index: Struktur Modal Sebagai Variabel Intervening

This study aims to analyze the profitability and capital structure of stock prices. The direct effect of profitability illustrated by ROA, ROE, NPM and EPS, and the capital structure proxied by DER on stock prices and the indirect effect of ROA, ROE, NPM, and EPS on stock prices through the Jakarta Islamic Index (JII) capital structure . The population in this study were 30 companies in the Jakarta Islamic Index (JII) for the 2015-2018 period. The results of this study found that ROA and NPM have a negative effect on stock prices. But NPM has a significant effect while ROA is not significant. ROE and EPS are both positive and significant effect on stock prices. The capital structure does not mediate the ROA and NPM variables but mediate the ROE and EPS variables on stock pricesKeyword : Profitability, Capital Structure, Stock Pric

Small RNAs Reflect Grandparental Environments in Apomictic Dandelion

Plants can show long-term effects of environmental stresses and in some cases a stress “memory” has been reported to persist across generations, potentially mediated by epigenetic mechanisms. However, few documented cases exist of transgenerational effects that persist for multiple generations and it remains unclear if or how epigenetic mechanisms are involved. Here, we show that the composition of small regulatory RNAs in apomictic dandelion lineages reveals a footprint of drought stress and salicylic acid treatment experienced two generations ago. Overall proportions of 21 and 24 nt RNA pools were shifted due to grandparental treatments. While individual genes did not show strong up- or downregulation of associated sRNAs, the subset of genes that showed the strongest shifts in sRNA abundance was significantly enriched for several GO terms including stress-specific functions. This suggests that a stress-induced signal was transmitted across multiple unexposed generations leading to persistent changes in epigenetic gene regulation

How Morphological Constraints Affect Axonal Polarity in Mouse Neurons

Neuronal differentiation is under the tight control of both biochemical and physical information arising from neighboring cells and micro-environment. Here we wished to assay how external geometrical constraints applied to the cell body and/or the neurites of hippocampal neurons may modulate axonal polarization in vitro. Through the use of a panel of non-specific poly-L-lysine micropatterns, we manipulated the neuronal shape. By applying geometrical constraints on the cell body we provided evidence that centrosome location was not predictive of axonal polarization but rather follows axonal fate. When the geometrical constraints were applied to the neurites trajectories we demonstrated that axonal specification was inhibited by curved lines. Altogether these results indicated that intrinsic mechanical tensions occur during neuritic growth and that maximal tension was developed by the axon and expressed on straight trajectories. The strong inhibitory effect of curved lines on axon specification was further demonstrated by their ability to prevent formation of multiple axons normally induced by cytochalasin or taxol treatments. Finally we provided evidence that microtubules were involved in the tension-mediated axonal polarization, acting as curvature sensors during neuronal differentiation. Thus, biomechanics coupled to physical constraints might be the first level of regulation during neuronal development, primary to biochemical and guidance regulations