Use of ordination and classification procedures to evaluate phytoplankton communities during Superflux II

Cluster analysis and an ordination procedure were performed on two data matrices to investigate real and environmental spatial relationships. Multiple regression analysis was used to relate the measured environmental variables to the phytoplankton community changes. Qualitative type phytoplankton data proved to be less structured in both of these spaces, relative to the biomass data. The salinity gradients of the northern transects covaried significantly with the phytoplankton association changes. In the southern transects the light variable was most important in explaining the variance in the ordination axes. These data suggest the close relationships between phytoplankton community changes and the physical hydrology of the area

Reactive attachment disorder in the general population: a hidden ESSENCE disorder

Reactive attachment disorder (RAD) is a severe disorder of social functioning. Previous research has shown that children with RAD may have poor cognitive and language abilities; however, findings mainly come from biased, institutionalised samples. This paper describes the characteristics of all children who were given a suspected or likely diagnosis of reactive attachment disorder in an epidemiological study of approximately 1,600 children investigating the prevalence of RAD in the general population. We found that children with RAD are more likely to have multiple comorbidities with other disorders, lower IQs than population norms, more disorganised attachment, more problem behaviours, and poorer social skills than would be found in the general population and therefore have a complex presentation than can be described as ESSENCE. We discuss the clinical and educational implications

Snowex 2017 Community Snow Depth Measurements: A Quality-Controlled, Georeferenced Product

Snow depth was one of the core ground measurements required to validate remotely-sensed data collected during SnowEx Year 1, which occurred in Colorado. The use of a single, common protocol was fundamental to produce a community reference dataset of high quality. Most of the nearly 100 Grand Mesa and Senator Beck Basin SnowEx ground crew participants contributed to this crucial dataset during 6-25 February 2017. Snow depths were measured along ~300 m transects, whose locations were determined according to a random-stratified approach using snowfall and tree-density gradients. Two-person teams used snowmobiles, skis, or snowshoes to travel to staked transect locations and to conduct measurements. Depths were measured with a 1-cm incremented probe every 3 meters along transects. In shallow areas of Grand Mesa, depth measurements were also collected with GPS snow-depth probes (a.k.a. MagnaProbes) at ~1-m intervals. During summer 2017, all reference stake positions were surveyed with <10 cm accuracy to improve overall snow depth location accuracy. During the campaign, 193 transects were measured over three weeks at Grand Mesa and 40 were collected over two weeks in Senator Beck Basin, representing more than 27,000 depth values. Each day of the campaign depth measurements were written in waterproof field books and photographed by National Snow and Ice Data Center (NSIDC) participants. The data were later transcribed and prepared for extensive quality assessment and control. Common issues such as protocol errors (e.g., survey in reverse direction), notebook image issues (e.g., halo in the center of digitized picture), and data-entry errors (sloppy writing and transcription errors) were identified and fixed on a point-by-point basis. In addition, we strove to produce a georeferenced product of fine quality, so we calculated and interpolated coordinates for every depth measurement based on surveyed stakes and the number of measurements made per transect. The product has been submitted to NSIDC in csv format. To educate data users, we present the study design and processing steps that have improved the quality and usability of this product. Also, we will address measurement and design uncertainties, which are different in open vs. forest areas

Scaling Symmetries of Scatterers of Classical Zero-Point Radiation

Classical radiation equilibrium (the blackbody problem) is investigated by the use of an analogy. Scaling symmetries are noted for systems of classical charged particles moving in circular orbits in central potentials V(r)=-k/r^n when the particles are held in uniform circular motion against radiative collapse by a circularly polarized incident plane wave. Only in the case of a Coulomb potential n=1 with fixed charge e is there a unique scale-invariant spectrum of radiation versus frequency (analogous to zero-point radiation) obtained from the stable scattering arrangement. These results suggest that non-electromagnetic potentials are not appropriate for discussions of classical radiation equilibrium.Comment: 13 page

Polarization effects in millimeter wave propagation through rain: A review of present theory and a discussion of current experiments

An attempt was made to calculate the depolarization effects of rain on linearly or elliptically polarized millimeter waves. Results are given in graphs and tables

Job Search and Frictional Unemployment : Some Empirical Evidence

L'auteur du présent article expose les résultats d'une enquête destinée à fournir certaines informations supplémentaires au sujet du chômage frictionnel.Il définit d'abord ce type de chômage à partir d'une formule algébrique, puis indique trois formes de chômage frictionnel: un chômage transitoire résultant de la mise à pied des salariés, un chômage volontaire lorsque ceux-ci quittent volontairement leur emploi, un chômage d'entrée au travail, lorsqu'il s'agit des personnes qui arrivent ou reviennent sur le marché du travail.Dans un deuxième temps, il soulève un autre élément de cette forme de chômage, soit la période plus ou moins longue au cours de laquelle les travailleurs sont à la recherche d'un emploi. Comme le chômage frictionnel est censé se produire lorsque les offres d'emploi sont égales ou supérieures aux demandes d'emploi, il est important de savoir pourquoi les travailleurs ne se placent pas immédiatement. D'une façon générale, on admet que quatre raisons principales peuvent expliquer le chômage frictionnel: 1° les travailleurs peuvent agir au hasard dans la recherche d'un emploi; 2° ils se peut qu'ils soient insuffisamment informés quant aux emplois vacants; 3° ils peuvent se réserver un temps plus ou moins long afin de recueillir des renseignements plus complets; 4° il peut arriver qu'ils mettent délibérément de côté certains emplois vacants.L'auteur, comme bien d'autres économistes, se posent un certain nombre de questions relatives au fait du chômage frictionnel. Les travailleurs en chômage sont-ils insuffisamment informés des conditions du marché du travail? Pendant qu'ils sont sans travail, s'efforcent-t-ils de se renseigner davantage sur l'existence des emplois vacants? Selon quels critères, décident-ils de solliciter un emploi? Tiennent-ils compte des conditions de travail et des taux de salaire?L'auteur a voulu procéder autrement, et voici comment. Il a choisi, aux fins de sa recherche, dans la ville d'Edmonton en Alberta l'endroit où étaient concentrées un grand nombre d'entreprises, soit ce qu'on appelle communément « le centre des affaires. » Il a fait porter son enquête sur une seule occupation, soit celle de dactylo. On leur a demandé combien de temps elles étaient demeurées sans emploi avant d'obtenir leur poste actuel, si elles se trouvaient suffisamment informées lorsqu'elles sont devenues sans travail, quelles furent leurs sources de renseignements au cours de leur périodede chômage et selon quels critères elles ont choisi les entreprises où elles ont postulé des emplois. Enfin, on a tenté de savoir si elles avaient, entre-temps, refusé une offre et si les taux de salaire payés par les employeurs y étaient pour quelque chose.— 68% d'entre elles ont réussi à obtenir leur emploi actuel en moins de quatre semaines, alors que 12 des 21 qui restaient ne se sont pas mises aussitôt en chômage à la recherche d'un nouveau poste. Dans l'ensemble, la durée de la recherche d'un emploi a été de 5.7 semaines.— Au sujet des renseignements nécessaires à la découverte de ce nouvel emploi, 42 employées, 12% d'entre elles seulement, ont déclaré qu'elles n'étaient pas suffisamment informées, alors que 30, ou 45%, estimaient posséder de bonnes ou d'excellentes informations.— Les répondantes estiment aussi qu'elles ne considèrent pas le fait de s'enregistrer aux centres de main-d'oeuvre et aux agences de placement privées comme une activité de cueillette d'information, estimant que ces organismes ne sont que des extensions des bureaux de personnel des entreprises.Finalement, l'Auteur s'est enquis des critères utilisés par les employées pour décider d'accepter un poste. Fait surprenant, 32 dactylos ont rejeté une offre d'emploi et 12 en ont refusé plus d'un. La principale raison de ces refus étaient que les conditions salariales étaient inacceptables.De cette enquête, l'Auteur cherche à tirer quelques conclusions générales. L'hypothèse selon laquelle les travailleurs manquent de renseignements lorsqu'ils tombent en chômage n'est pas confirmée par les résultats de l'enquête.The purpose of this paper is to report on some recent empirical research undertaken in order to provide additional information concerning the frictionally unemployed

A Census of X-ray gas in NGC 1068: Results from 450ks of Chandra HETG Observation

We present models for the X-ray spectrum of the Seyfert 2 galaxy NGC 1068. These are fitted to data obtained using the High Energy Transmission Grating (HETG) on the Chandra X-ray observatory. The data show line and radiative recombination continuum (RRC) emission from a broad range of ions and elements. The models explore the importance of excitation processes for these lines including photoionization followed by recombination, radiative excitation by absorption of continuum radiation and inner shell fluorescence. The models show that the relative importance of these processes depends on the conditions in the emitting gas, and that no single emitting component can fit the entire spectrum. In particular, the relative importance of radiative excitation and photoionization/recombination differs according to the element and ion stage emitting the line. This in turn implies a diversity of values for the ionization parameter of the various components of gas responsible for the emission, ranging from log(xi)=1 -- 3. Using this, we obtain an estimate for the total amount of gas responsible for the observed emission. The mass flux through the region included in the HETG extraction region is approximately 0.3 Msun/yr assuming ordered flow at the speed characterizing the line widths. This can be compared with what is known about this object from other techniques.Comment: 39 pages, 12 figures, Ap. J. in pres

Monitoring and Discovering X-ray Pulsars in the Small Magellanic Cloud

Regular monitoring of the SMC with RXTE has revealed a huge number of X-ray pulsars. Together with discoveries from other satellites at least 45 SMC pulsars are now known. One of these sources, a pulsar with a period of approximately 7.8 seconds, was first detected in early 2002 and since discovery it has been found to be in outburst nine times. The outburst pattern clearly shows a period of 45.1 +/- 0.4 d which is thought to be the orbital period of this system. Candidate outburst periods have also been obtained for nine other pulsars and continued monitoring will enable us to confirm these. This large number of pulsars, all located at approximately the same distance, enables a wealth of comparative studies. In addition, the large number of pulsars found (which vastly exceeds the number expected simply by scaling the relative mass of the SMC and the Galaxy) reveals the recent star formation history of the SMC which has been influenced by encounters with both the LMC and the Galaxy.Comment: 5 pages, 4 figures, AIP conference proceedings format. Contribution to "X-ray Timing 2003: Rossi and Beyond." meeting held in Cambridge, MA, November, 200