Assessing relationships of moose populations, winter ticks, and forest regeneration in northern New Hampshire

This study examined relationships among winter ticks, weather, and the nutritional and reproductive status of moose, and the impact of moose on regeneration of commercial forests in northern New Hampshire. Three methods were evaluated to assess their usefulness as indices of relative winter tick abundance, and predictors of tick epizootics: tick counts on harvested moose and roadside, spring hair-loss surveys were considered time and cost effective to index winter tick abundance. Physical characteristics of harvested moose (1988--2009) indicated ovulation rates (∼20%), and mean body weight (\u3c200 kg) of yearlings declined since 1988; because adult body weight and ovulation rates remained stable, habitat quality was unlikely related. Winter tick epizootics are likely influenced by abnormal large scale weather events, as evident in the widespread die-off in 2002 associated with warm snowless conditions into mid-December 2001 that extended tick transmission to moose. Spring and fall weather should be monitored for unusual conditions causing high tick abundance and tick loads, particularly warm and snowless conditions in April and December. Mean stocking rate of all age classes of commercial tree species was above the threshold in all regions (49--87%); forest regeneration was not considered a regional problem at any moose density

Constraining the photometric properties of MgII absorbing galaxies with the SDSS

Using a sample of nearly 700 quasars with strong (W_0(2796)>0.8 Angstrom) MgII absorption lines detected in the Early Data Release of the SDSS, we demonstrate the feasibility of measuring the photometric properties of the absorber systems by stacking SDSS imaging data. As MgII lines can be observed in the range 0.37<z_abs<2.2, the absorbing galaxies are in general not identified in SDSS images, but they produce systematic light excesses around QSOs which can be detected with a statistical analysis. In this Letter we present a 6-sigma detection of this effect over the whole sample in i-band, rising to 9.4-sigma for a low-redshift subsample with 0.37<z_abs<=0.82. We use a control sample of QSOs without strong MgII absorption lines to quantify and remove systematics with typical 10-20% accuracy. The signal varies as expected as a function of absorber redshift. For the low z_abs subsample we can reliably estimate the average luminosities per MgII absorber system in the g, r, and i bands and find them to be compatible with a few-hundred-Myr old stellar population of M_r ~ -21 in the rest frame. Colors are also consistent with typical absorbing galaxies resembling local Sb-c spirals. Our technique does not require any spectroscopic follow-up and does not suffer from confusion with other galaxies arising along the line-of-sight. It will be applied to larger samples and other line species in upcoming studies.Comment: Accepted on ApJ Letters, 5 pages, 2 figure

Optical properties and spatial distribution of MgII absorbers from SDSS image stacking

We present a statistical analysis of the photometric properties and spatial distribution of more than 2,800 MgII absorbers with 0.37<z<1 and rest equivalent width W_0(\lambda2796)>0.8\AA detected in SDSS quasar spectra. Using an improved image stacking technique, we measure the cross-correlation between MgII gas and light (in the g, r, i and z-bands) from 10 to 200 kpc and infer the light-weighted impact parameter distribution of MgII absorbers. Such a quantity is well described by a power-law with an index that strongly depends on W_0, ranging from ~-1 for W_0~ 1.5\AA. At redshift 0.37<z<0.55, we find the average luminosity enclosed within 100 kpc around MgII absorbers to be M_g=-20.65+-0.11 mag, which is ~0.5 L_g*. The global luminosity-weighted colors are typical of present-day intermediate type galaxies. However, while the light of weaker absorbers originates mostly from red passive galaxies, stronger systems display the colors of blue star-forming galaxies. Based on these observations, we argue that the origin of strong MgII absorber systems might be better explained by models of metal-enriched gas outflows from star-forming/bursting galaxies. Our analysis does not show any redshift dependence for both impact parameter and rest-frame colors up to z=1. However, we do observe a brightening of the absorbers related light at high redshift (~50% from z~0.4 to 1). We argue that MgII absorbers are a phenomenon typical of a given evolutionary phase that more massive galaxies experience earlier than less massive ones, in a downsizing fashion. (abridged)Comment: ApJ in press, 28 pages, 16 figures, using emulateapj. Only typo corrections wrt the original submission (v1

La Grande dépression américaine et la neutralité de la monnaie : un test économétrique

Dans ce texte, nous utilisons des données de la période de l’entre-deux-guerres aux États-Unis pour vérifier l’hypothèse de la neutralité de la monnaie. Dans l’ensemble, nos résultats démontrent que l’hypothèse de la neutralité est rejetée par les données même dans le cas où l’on élimine la variable de faillites bancaires du domaine de l’information disponible dans l’équation d’anticipation de la monnaie. Ces résultats vont donc à l’encontre de ceux obtenus pour l’après-guerre par Barro (1977, 1978) et Barro et Rush (1980) mais vont dans le sens de ceux de Mishkin (1982).In this paper, the neutrality hypothesis is tested for the U.S. Great Depression. Neutrality is generally rejected by the data even when banking failures are excluded from the available information set in generating the anticipated rate of growth of money series. Hence our results are contrary to those of Barro (1977, 1978) and Barro and Rush (1980) for the Post War years. They confirm those of Mishkin (1982)

Damped Lyman Alpha Systems at z<1.65: The Expanded SDSS HST Sample

We present results of our HST Cycle 11 Survey for low-redshift (z<1.65) DLAs in the UV spectra of quasars selected from the SDSS Early Data Release. These quasars have strong intervening MgII-FeII systems which are known signatures of high column density neutral gas. In total, UV observations of Ly-alpha absorption in 197 MgII systems with z<1.65 and rest equivalent width (REW) W2796 \ge 0.3A have now been obtained. The main results are: (1) 36(+/- 6)% of systems with W2796 \ge 0.5 A and FeII W2600 \ge 0.5 A are DLAs. This increases to 42(+/- 7)% for systems with W2796/W2600 0.1 A. (2) The mean N(HI) of MgII systems with 0.3 A \le W2796 < 0.6 A is a factor of ~36 lower than that of systems with W2796 \ge 0.6 A. (3) The DLA incidence per unit redshift is consistent with no evolution for z <~ 2 (Omega_L=0.7, Omega_M = 0.3), but exhibits significant evolution for z >~ 2. (4) Omega_{DLA} is constant for 0.5<z<5.0 to within the uncertainties. This is larger than Omega_{gas}(z=0) by a factor of ~2. (5) The slope of the N(HI) distribution does not change significantly with redshift. However, the low redshift distribution is marginally flatter due to the higher fraction of high N(HI) systems in our sample. (6) Finally, using the precision of MgII survey statistics, we find that there may be evidence of a decreasing Omega_{DLA} from z=0.5 to z=0. We reiterate the conclusion of Hopkins, Rao, & Turnshek that very high columns of neutral gas might be missed by DLA surveys because of their very small cross sections, and therefore, that Omega_{DLA} might not include the bulk of the neutral gas mass in the Universe. (Abridged)Comment: Accepted for publication in ApJ. 22 pages, 22 figure

La Grande dépression américaine et la neutralité de la monnaie : un test économétrique

In this paper, the neutrality hypothesis is tested for the U.S. Great Depression. Neutrality is generally rejected by the data even when banking failures are excluded from the available information set in generating the anticipated rate of growth of money series. Hence our results are contrary to those of Barro (1977, 1978) and Barro and Rush (1980) for the Post War years. They confirm those of Mishkin (1982). Dans ce texte, nous utilisons des données de la période de l’entre-deux-guerres aux États-Unis pour vérifier l’hypothèse de la neutralité de la monnaie. Dans l’ensemble, nos résultats démontrent que l’hypothèse de la neutralité est rejetée par les données même dans le cas où l’on élimine la variable de faillites bancaires du domaine de l’information disponible dans l’équation d’anticipation de la monnaie. Ces résultats vont donc à l’encontre de ceux obtenus pour l’après-guerre par Barro (1977, 1978) et Barro et Rush (1980) mais vont dans le sens de ceux de Mishkin (1982).