Supernova bound on keV-mass sterile neutrinos reexamined

Active-sterile neutrino mixing is strongly constrained for m_s > 100 keV to avoid excessive energy losses from supernova cores. For smaller m_s, matter effects suppress the effective mixing angle except for a resonant range of energies where it is enhanced. We study the case of \nu_tau-\nu_s-mixing where a \nu_tau-\bar\nu_tau asymmetry builds up due to the strong excess of \nu_s over \bar\nu_s emission or vice versa, reducing the overall emission rate. In the warm dark matter range m_s < 10 keV the mixing angle is essentially unconstrained.Comment: 6 pages, 4 figures; minor changes, references updated, matches the published versio

Testing neutrino instability with active galactic nuclei

Active galactic nuclei and gamma ray bursts at cosmological distances are sources of high-energy electron and muon neutrinos and provide a unique test bench for neutrino instability. The typical lifetime-to-mass ratio one can reach there is $\tau/m\sim 500 Mpc/cE_{\nu}\sim 500$ s/eV. We study the rapid decay channel $\nu_i\to\nu_j+\phi$, where $\phi$ is a massless or very light scalar (possibly a Goldstone boson), and point out that one can test the coupling strength of $g_{ij}\nu_i\nu_j$ down to g_{ij}\lsim 10^{-8} eV/m by measuring the relative fluxes of $\nu_{e}$, $\nu_{\mu}$ and $\nu_{\tau}$. This is orders of magnitude more stringent bound than what one can obtain in other phenomena, e.g. in neutrinoless double beta decay with scalar emission.Comment: 3 page

Muutokset alakouluikäisten fyysisessä aktiivisuudessa 2000-luvulla

Tiivistelmä. Tutkielman tarkoituksena oli tarkastella alakouluikäisten lasten fyysistä aktiivisuutta ja sen muutoksia 2000-luvun aikana. Lisäksi tavoitteena oli kuvata muutoksia alakouluikäisten urheiluseuratoimintaan osallistumisessa 2000-luvulla. Tarkastelimme myös koronapandemian vaikutuksia alakouluikäisten liikkumiseen sekä urheiluseuratoimintaan. Toteutimme tutkielman kuvailevana kirjallisuuskatsauksena. Tutkielman aihe on merkittävä, koska lapsena ja nuorena opittu fyysisesti aktiivinen elämäntapa luo tutkitusti hyvät edellytykset terveelle ja hyvinvoivalle elämälle. Fyysisesti aktiivinen elämäntapa on merkittävää kansanterveyden näkökulmasta, sillä liikkuminen vaikuttaa positiivisesti lasten ja nuorten fyysiseen, psyykkiseen sekä sosiaaliseen terveyteen. Aihepiiristä tehty aiempi tutkimus osoittaa, että huoli lasten liikkumisesta ja fyysisen suorituskyvyn heikkenemisestä on aiheellinen. Tehty tutkimus osoittaa, että suuri osa alakouluikäisistä liikkuu liian vähän liikkumissuosituksiin nähden. Kuitenkin 2000-luvun aikana tehdyistä tutkimuksista voidaan havaita pientä positiivista kehitystä fyysisen kokonaisaktiivisuuden osalta. Urheiluseuratoimintaan osallistuminen kasvoi tasaisesti 2000-luvun aikana alakouluikäisillä lapsilla, kunnes koronapandemia rajoitti harrastusmahdollisuuksia ja osallistuminen kääntyi ainakin väliaikaisesti laskuun. Lisäksi koronapandemia aiheutti askelmäärien merkittävää vähentymistä alakouluikäisillä lapsilla. 2000-luvun aikana tapahtuneesta positiivisesta kehityksestä huolimatta liikkumisen määrää tulisi saada lisättyä alakouluikäisillä lapsilla. Koronapandemian pidempiaikaisia vaikutuksia fyysisen aktiivisuuden määrään ja urheiluseuratoimintaan on tärkeä tutkia pandemian jälkeen. Lasten fyysisen aktiivisuuden ja urheiluseuratoimintaan osallistumisen määrä olisi tärkeä saada palautettua koronapandemiaa edeltävälle tasolle. Jotta tulevaisuudessa yhä useampi lapsi liikkuisi liikkumissuositusten mukaan, täytyisi saada selville mitkä asiat motivoisivat liikkumaan niitä lapsia, jotka eivät tällä hetkellä liiku tarpeeksi

Neutrino Mass Texture with Large Mixing

We propose a simple texture for the right-handed Majorana mass matrix to give a large $\nu_\mu-\nu_\tau$ mixing angle and hierarchical left-handed neutrino mass pattern. Consistently with the Dirac mass texture of the quark sector realizing the CKM mixing, this naturally explains the recent experimental results on both the atmospheric neutrino anomaly observed by the Superkamiokande collaboration and the solar neutrino problem. In this texture the right-handed Majorana mass of the third generation is of the order of GUT scale, which is favorable for reproducing the observed bottom-tau mass ratio.Comment: 10 pages, LaTeX, comments and references adde

A Mass Matrix for Atmospheric, Solar, and LSND Neutrino Oscillations

We construct a mass matrix for the four neutrino flavors, three active and one sterile, needed to fit oscillations in all three neutrino experiments: atmospheric, solar, and LSND, simultaneously. It organizes the neutrinos into two doublets whose central values are about 1 eV apart, and whose splittings are of the order of 10^(-3) eV. Atmospheric neutrino oscillations are described as maximal mixing within the upper doublet, and solar as the same within the lower doublet. Then LSND is a weak transition from one doublet to the other. We comment on the Majorana versus Dirac nature of the active neutrinos and show that our mass matrix can be derived from an S_2 x S_2 permutation symmetry plus an equal splitting rule.Comment: 4 pages, 0 figures, minor text change

Detecting structural changes induced by Heterobasidion root rot on Scots pines using terrestrial laser scanning

Root rot, caused by the decay fungus Heterobasidion annosum, damages both below- and above-ground parts of Scots pines (Pinus Sylvestris L.). The diseased pines are often first characterized by deteriorated crowns and they will eventually be killed by the infection, but the process is gradual and difficult to be observed before the symptoms are severe. We tested the applicability of point cloud data produced by terrestrial laser scanning (TLS) for quantifying the structural differences between the healthy and the diseased trees. This approach was applied in a mature pine stand in southern Finland, which was known to be infected by H. annosum. We first scanned the stand using TLS, and thereafter felled the trees for detailed inspection and classification of the infection status. From the TLS point cloud, we estimated i) crosscut areas within the lowest 1 m of the stem, identifying potential deformations initiated by the fungus, ii) degree of crown deterioration, often providing the first visual signs of the infection at the level of individual trees, and iii) crown occupancy and open space around the trees, prone to be altered by the mycelial spread of the fungus between the adjacent trees. The results indicate that differences in both stem dimensions and crown deterioration can be detected between the healthy and the diseased trees. The diseased trees were found to have a more swollen butt, but no irregularities in circularity of the crosscuts were detected. In terms of vertical point distribution, the diseased trees had point accumulations at substantially greater heights, reflecting easier penetration of laser beams and sparsity of the crown. Regarding to crown occupancy, the diseased trees had more open space around their crowns, but difference to the healthy trees was not statistically significant. According to a simple prediction test based on the calculated features, up to 85% classification accuracy of the infection status was reached. This study is the first indication that TLS can successfully be applied for detecting structural changes of Scots pines connected to Heterobasidion root rot. Our results also show evidence that H. annosum causes butt swelling, which has rarely been reported as a symptom for Scots pines

Four species neutrino oscillations at ν\nu-Factory: sensitivity and CP-violation

The prospects of measuring the leptonic angles and CP-odd phases at a {\em neutrino factory} are discussed in the scenario of three active plus one sterile neutrino. We consider the \nu_\mu \raw \nu_e LSND signal. Its associated large mass difference leads to observable neutrino oscillations at short ($\sim 1$ km) baseline experiments. Sensitivities to the leptonic angles down to $10^{-3}$ can be easily achieved with a 1 Ton detector. Longer baseline experiments ($\sim 100$ km) with a 1 Kton detector can provide very clean tests of CP-violation especially through tau lepton detection.Comment: 15 pages, LaTeX2e, 14 eps files, use package epsfi

Neutrino mixing and CP-violation

The prospects of measuring the leptonic angles and CP-odd phases at a neutrino factory are discussed in two scenarios: 1) three active neutrinos as indicated by the present ensemble of atmospheric plus solar data; 2) three active plus one sterile neutrino when the LSND signal is also taken into account. For the latter we develop one and two mass dominance approximations. The appearance of wrong sign muons in long baseline experiments and tau leptons in short baseline ones provides the best tests of CP-violation in scenarios 1) and 2), respectively.Comment: 22 pages, LaTeX2e, 17 eps files, use package epsfi

Light Sterile Neutrino from extra dimensions and Four-Neutrino Solutions to Neutrino Anomalies

We propose a four-neutrino model which can reconcile the existing data coming from underground experiments in terms of neutrino oscillations, together with the hint from the LSND experiment and a possible neutrino contribution to the hot dark matter of the Universe. It applies the idea that extra compact dimensions, probed only by gravity and possibly gauge-singlet fields, can lower the fundamental scales such as the Planck, string or unification scales. Our fourth light neutrino $\nu_s$ ($s$ for sterile) is identified with the zero mode of the Kaluza-Klein states. To first approximation \nu_sterile combines with the nu_mu in order to form a Dirac neutrino with mass in the eV range leaving the other two neutrinos massless. The smallness of this mass scale (suitable for LSND and Hot Dark Matter) arises without appealing neither to a see-saw mechanism nor to a radiative mechanism, but from the volume factor associated with the canonical normalization of the wave-function of the bulk field in the compactified dimensions. % On the other hand the splitting between \nm and \nu_sterile (atmospheric scale) as well as the mass of the two other neutrinos (solar mass scale) arise from the violation of the fermion number on distant branes. We also discuss alternative scenarios involving flavour-changing interactions. In one of them \ne can be in the electron-volt range and therefore be probed in beta decay studies.Comment: 12 pages, latex, no figures, title changed, final version to be published in Phys Rev