INTEGRAL/XMM views on the MeV source GRO J1411-64

The COMPTEL unidentified source GRO J 1411-64 was observed by INTEGRAL and XMM-Newton in 2005. The Circinus Galaxy is the only source detected within the 4σ location error of GRO J1411-64, but in here excluded as the possible counterpart. At soft X-rays, 22 reliable and statistically significant sources (likelihood >10) were extracted and analyzed from XMM-Newton data. Only one of these sources, XMMU J141255.6-635932, is spectrally compatible with GRO J1411-64 although the fact the soft X-ray observations do not cover the full extent of the COMPTEL source position uncertainty make an association hard to quantify and thus risky. At the best location of the source, detections at hard X-rays show only upper limits, which, together with MeV results obtained by COMPTEL suggest the existence of a peak in power output located somewhere between 300–700 keV for the so-called low state. Such a spectrum resembles those in blazars or microquasars, and might suggest at work by the models accordingly. However, an analysis using a microquasar model consisting on a magnetized conical jet filled with relativistic electrons, shows that it is hard to comply with all observational constrains. This fact and the non-detection at hard X-rays introduce an a-posteriori question mark upon the physical reality of this source, what is discussed here.     

Temperature variability and early clustering of record-breaking events

As the number of climatological studies using record-breaking statistics is growing rapidly, understanding the sensitivity of the chosen time period becomes essential. To that end, here we examine the evolving variability of monthly mean temperatures and its dependence on beginning and final year. Specifically, we use an index, α, based on record-breaking statistics and employing reversibility such that 〈α〉=0 indicates no trend in variability. Generally, 〈α〉 has decreased between 1900 and 2013, indicating decreasing variability relative to early decades for stations from the contiguous USA (United States Historical Climatology Network, version 2.5). We find, somewhat surprisingly, that the observed decrease is due to an early excess of records beginning in 1917 (record low value) and 1921 (record high value). While detailed results depend on whether the data is gridded, detrended, etc., the general finding appears remarkably robust and holds globally as well.     

Urban Community Garden Agrodiversity and Cultural Identity in Philadelphia,Pennsylvania, U.S.

Considerable research has examined the social, cultural, economic, and community benefits of urban gardening. Few studies, however, have empirically assessed factors that influence urban community garden agrodiversity or its relationship to these dimensions of gardening. We conducted an interdisciplinary study of agrodiversity and cultural identity, based certain markers of identity, including how people see themselves with respect to race, ethnicity, or place of origin, in community gardens in Philadelphia, Pennsylvania. We conducted fifty‐six semistructured interviews with gardeners with different cultural identities in eight community gardens on their motivations for urban community gardening during 2014. We conducted plant inventories of the corresponding garden plots and found 104 cultivated edible and ornamental species and 28 varieties representing 34 families. We find that although gardens with culturally diverse gardeners did not have higher species richness, the cultural identity of the gardeners influenced species selection and reason for gardening. Further, the structure, design and species composition of garden plots reflected the identities of garden members. These finding have implications for the recent institutionalization of urban agriculture into city land policies in Philadelphia and other cities in North America.     

Evidence of beneficial role of inclined piles: observations and summary of numerical analyses

The behaviour under seismic loading of inclined piles embedded in two idealized soil profiles, a homogeneous and a non-homogenous “Gibson” soil, is analysed with 3D finite elements. Two structures, modeled as single-degree-of-freedom oscillators, are studied: (1) a tall slender superstructure (H _st = 12 m) whose crucial loading is the overturning moment, and (2) a short structure (H _st = 1 m) whose crucial loading is the shear force. Three simple two-pile group are studied: (a) one comprising a vertical pile and a pile inclined at 25°, (b) one consisting of two piles symmetrically inclined at 25°, and (c) a group of two vertical piles. The influence of key parameters is analysed and non-dimensional diagrams are presented to illustrate the role of raked piles on pile and structure response. It is shown that this role can be beneficial or detrimental depending on a number of factors, including the slenderness of the superstructure and the type of pile-to-cap connection.     

A New Ionosphere Monitoring Technology Based on GPS

Although global positioning system (GPS) was originally planned as a satellite-based radio-navigation system for military purposes, civilian users have significantly increased their access to the system for both, commercial and scientific applications. Almost 400 permanent GPS tracking stations have been stablished around the globe with the main purpose of supporting scientific research. In addition, several GPS receivers on board of low Earth orbit satellites fitted with special antennas that focus on Earth's horizon, are tracking the radio signals broadcasted by the high-orbiting GPS satellites, as they rise and set on Earth horizon. The data of these ground and space-born GPS receivers, readily accessible through Internet in a ‘virtual observatory’ managed by the International GPS Service, are extensively used for many researches and might possibly ignite a revolution in Earth remote sensing. By measuring the changes in the time it takes for the GPS signals to arrive at the receiver as they travel through Earth's atmosphere, scientists can derive a surprising amount of information about the Earth's ionosphere, a turbulent shroud of charged particles that, when stimulated by solar flares, can disrupt communications around the world. This contribution presents a methodology to obtain high temporal resolution images of the ionospheric electron content that lead to two-dimensional vertical total electron content maps and three-dimensional electron density distribution. Some exemplifying results are shown at the end of the paper.     

Downwelling Events in a Coastal Mussel Farming Area,NW Thessaloniki’s Gulf (NW Aegean Sea)

Ocean Science Journal - The coastal area of Chalastra (NW Thessaloniki’s Gulf, Northern Greece) features prominent mussel farming activity as well as fishing activity. These activities are...     

全新世东地中海的陆源碎屑输入及其水文气候变化:海盆尺度地球化学分析

地中海位于非洲季风气候和欧洲温带气候的交界处,同时接受周边地区岩石性质和风化状况差异极大的碎屑物质,所以是研究地球表层水文循环的理想区域。前人的认识集中于撒哈拉风尘和尼罗河输入,往往忽视了其他的陆源碎屑沉积,尤其对不同水文气候条件下的潜在变化缺乏考虑。针对形成于全新世非洲湿润期的腐泥层S1页岩沉积,并结合采自岩心顶部的晚全新世/现代沉积物,文章从18个站位选取了30个样品开展碎屑组分的地球化学分析,通过在具有不同干湿环境背景的时间片段上开展盆地尺度的对比(约9.5~8.9 ka vs. 约1.7~0 ka),探讨全新世东地中海的陆源碎屑输入模式。Ti/Al、Zr/Al、Ca/Al、Y/Al都清晰显示了经向和纬向上的梯度变化,可用作撒哈拉风尘的可靠指标;这些碎屑元素之间的差异反映了北非风尘来源和传送路径的变化。这些风尘指标在南-北向上的一致变化指示了副热带高压与西风带的交互界限为36°N,该界限在全新世应稳定存在。与风尘相反,河流输入的指标值在早全新世时显著高于现代,并呈现不同的地理分布。K/Al具有西高东低、北高南低的分布特征,指示了地中海北部沿岸地区的河流输入。根据与Ti/Al、K/Al的差异,利用(Cr+Ni)/Al可较好地识别被增强的季风降雨所激活的北非古河流沉积。河流输入在早全新世时显著上升,但不同河流系统的影响范围差异很大,受制于源区水文气候、表层洋流搬运等因素。