Regularized principal manifolds

Many settings of unsupervised learning can be viewed as quantization problems - the minimization of the expected quantization error subject to some restrictions. This allows the use of tools such as regularization from the theory of (supervised) risk minimization for unsupervised learning. This setting turns out to be closely related to principal curves, the generative topographic map, and robust coding. We explore this connection in two ways: (1) we propose an algorithm for nding principal manifolds that can be regularized in a variety of ways; and (2) we derive uniform convergence bounds and hence bounds on the learning rates of the algorithm. In particular, we give bounds on the covering numbers which allows us to obtain nearly optimal learning rates for certain types of regularization operators. Experimental results demonstrate the feasibility of the approach

Mufasa: The assembly of the red sequence

We examine the growth and evolution of quenched galaxies in the Mufasa cosmo- logical hydrodynamic simulations that include an evolving halo mass-based quench- ing prescription, with galaxy colours computed accounting for line-of-sight extinc- tion to individual star particles. Mufasa reproduces the observed present-day red sequence quite well, including its slope, amplitude, and scatter. In Mufasa, the red sequence slope is driven entirely by the steep stellar mass{stellar metallicity relation, which independently agrees with observations. High-mass star-forming galaxies blend smoothly onto the red sequence, indicating the lack of a well-de ned green valley at M & 1010:5M . The most massive galaxies quench the earliest and then grow very little in mass via dry merging; they attain their high masses at earlier epochs when cold in ows more e ectively penetrate hot halos. To higher redshifts, the red sequence becomes increasingly contaminated with massive dusty star-forming galaxies; UVJ selection subtly but e ectively separates these populations. We then examine the evo- lution of the mass functions of central and satellite galaxies split into passive and star-forming via UVJ. Massive quenched systems show good agreement with obser- vations out to z 2, despite not including a rapid early quenching mode associated with mergers. However, low-mass quenched galaxies are far too numerous at z . 1 in Mufasa, indicating that Mufasa strongly over-quenches satellites. A challenge for hydrodynamic simulations is to devise a quenching model that produces enough early massive quenched galaxies and keeps them quenched to z = 0, while not being so strong as to over-quench satellites; Mufasa only succeeds at the former.IS

Dietary Prebiotics and Bioactive Milk Fractions Improve NREM Sleep, Enhance REM Sleep Rebound and Attenuate the Stress-Induced Decrease in Diurnal Temperature and Gut Microbial Alpha Diversity.

Severe, repeated or chronic stress produces negative health outcomes including disruptions of the sleep/wake cycle and gut microbial dysbiosis. Diets rich in prebiotics and glycoproteins impact the gut microbiota and may increase gut microbial species that reduce the impact of stress. This experiment tested the hypothesis that consumption of dietary prebiotics, lactoferrin (Lf) and milk fat globule membrane (MFGM) will reduce the negative physiological impacts of stress. Male F344 rats, postnatal day (PND) 24, received a diet with prebiotics, Lf and MFGM (test) or a calorically matched control diet. Fecal samples were collected on PND 35/70/91 for 16S rRNA sequencing to examine microbial composition and, in a subset of rats; Lactobacillus rhamnosus was measured using selective culture. On PND 59, biotelemetry devices were implanted to record sleep/wake electroencephalographic (EEG). Rats were exposed to an acute stressor (100, 1.5 mA, tail shocks) on PND 87 and recordings continued until PND 94. Test diet, compared to control diet, increased fecal Lactobacillus rhamnosus colony forming units (CFU), facilitated non-rapid eye movement (NREM) sleep consolidation (PND 71/72) and enhanced rapid eye movement (REM) sleep rebound after stressor exposure (PND 87). Rats fed control diet had stress-induced reductions in alpha diversity and diurnal amplitude of temperature, which were attenuated by the test diet (PND 91). Stepwise multiple regression analysis revealed a significant linear relationship between early-life Deferribacteres (PND 35) and longer NREM sleep episodes (PND 71/72). A diet containing prebiotics, Lf and MFGM enhanced sleep quality, which was related to changes in gut bacteria and modulated the impact of stress on sleep, diurnal rhythms and the gut microbiota

Spontaneous cerebrospinal fluid leak at the clivus

We present a case report of a 60-year-old woman with a spontaneous cerebrospinal fluid leak at the clivus, obesity and no history of trauma. Follow-up imaging scans confirmed enlargement of the defect within the posterior clival framework to the size of 16 × 9 × 4 mm with a suspected meningocerebral hernia. The surgeons used the “two nostrils – four hands” endoscopic operating technique. The patient reported a history of cerebrospinal fluid leaks lasting for 3 years, with increasingly shorter leak-free periods and an increasing incidence of inflammatory complications. The patient recovered without complications, and she was discharged 14 days after the surgery. Good local outcome and improved patient condition were achieved postoperatively

Friends Without Benefits?:New EMU Members and the “Euro Effect” on Trade

We re-visit the evidence about the trade benefits of European Monetary Union (EMU), focusing on the experience of countries which adopted the common currency since 2002. Based on “state of the art” gravity estimations for the period 1992-2013, we reach three main conclusions. First, estimates from an appropriately specified and estimated gravity equation provide no evidence of a euro effect on trade flows among early euro adopters up to the year 2002. Second, this finding is robust to extending the sample period to incorporate data up to 2013, covering five additional euro accessions. Third, while there is no robust evidence of a euro effect, there is evidence that intra-EU trade flows have expanded faster than the global average during the 2002-2013 period. Using the functional form of a theory-consistent gravity equation, we perform pseudo out-of-sample forecasts of trade flows for recent euro joiners. In line with our estimation results, we show that pseudo forecasts of the change in trade flows after euro accession, assuming no euro effect, outperform forecasts based on the expectation of a significantly positive effect. This suggests that euro accession countries should not expect a significant boost to their trade from joining EMU

Spatial variability of functional brain networks in early-blind and sighted subjects

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