Aerodynamic properties of fractal grains: Implications for the primordial solar nebula

Under conditions in the primordial solar nebula and dense interstellar clouds, small grains have low relative velocities. This is the condition for efficient sticking and formation of fractal aggregates. A calculation of the ratio of cross section, sigma, to number of primary particles, N, for fractal clusters yielded 1n sigma/N = 0.2635 + 0.5189N sup (-0.1748). This ratio decreases slowly with N and approaches a constant for large N. Under the usual assumption of collisions producing spherical compact, uniform density aggregates, sigma/N varies as N sup -1/3 and decreases rapidly. Fractal grains are therefore much more closely coupled to the gas than are compact aggregates. This has a significant effect on the aerodynamic behavior of aggregates and consequently on their evolution and that of the nebula

Book review: energy, capitalism and world order: toward a new agenda in international political economy edited by Tim Di Muzio and Jesse Salah Ovadia

In the new collection Energy, Capitalism and World Order: Towards a New Agenda in International Political Economy, editors Tim Di Muzio and Jesse Salah Ovadia bring together contributors to examine the relationship between energy, capitalism and the world order in light of pressing and emergent issues such as fracking, biofuels and climate change. While more attention on the diverse challenges faced by different political economies would have been welcome, this collection presents lucid analyses and grounded case studies that will be of use to scholars, students and policymakers, finds Donn David P. Ramos

On the formation of graphite grains in cool stars

Graphite grain formation in cool stars examined on basis of molecular equilibrium data for stellar atmosphere

All the way to the top! The energy implications of building tall cities

Density of urban form may be achieved under a variety of morphological designs that do not rely on tallness alone. Tall buildings have implications on the broader urban environment and infrastructure that lower buildings would not have, e.g. wind effects, sight-lines, or over-shading. They may also have an impact on energy use for reasons of buildings-physics, construction, and occupant practices. This study uses a statistical approach of neighbourhood level data to analyse the impact of building morphology (e.g. height, volume and density) on energy demand in 12 local authorities in London. The research shows that areas marked by tall buildings use more gas after adjusting for exposures surface area, volume, number of residents and other features. The implication for energy policy and planning is building taller without increasing density may have an energy penalty

Energy use and height in office buildings

The relationship between energy use and height is examined for a sample of 611 office buildings in England and Wales using actual annual metered consumption of electricity and fossil fuels. The buildings are of different ages; they have different construction characteristics and methods of heating and ventilation; and they include both public and commercial offices. When rising from five storeys and below to 21 storeys and above, the mean intensity of electricity and fossil fuel use increases by 137% and 42% respectively, and mean carbon emissions are more than doubled. A multivariate regression model is used to interpret the contributions of building characteristics and other factors to this result. Air-conditioning is important, but a trend of increased energy use with height is also found in naturally ventilated buildings. Newer buildings are not in general more efficient: the intensity of electricity use is greater in offices built in recent decades, without a compensating decrease in fossil fuel use. The evidence suggests it is likely – although not proven – that much of the increase in energy use with height is due to the greater exposure of taller buildings to lower temperatures, stronger winds and more solar gains

DETERMINING THE EFFECTIVENESS OF PROFESSIONAL TRAININGS OF TEACHERS IN A LOCAL COLLEGE

Using the quantitative research method, the effectiveness of professional trainings that have been undertaken by teachers as well as the impact on teachers’ teaching practices were determined. It likewise explored whether teachers’ assessment scores were significantly associated with their profile characteristics. The common professional trainings undertaken include in-service trainings (100%), education conferences (97.1%), informal dialogue with colleagues (97.1%), and individual or group research (91.2%). Of all the professional training activities, only getting involved with teachers on how to improve teaching practice was assessed to be highly effective in developing their competence, knowledge, and expertise. However, benchmarking visits to other colleges or universities and faculty participation in a professional organization that are helpful to their teaching profession was determined to be only moderately effective. The respondents reported significant improvements in their teaching practices in connection with content and pedagogy, diversity of learners, community linkages, and professional engagement. A positive relationship was found between the variable age and respondents’ assessment scores on benchmarking visits to other colleges or universities and individual or group research on the field of interest. However, a negative relationship exists between respondents’ highest educational attainment and assessment scores on professional links with colleagues such as mentoring, and coaching among others as part of the institutional policy. Thus, a teacher’s training that encourages collaboration and sharing of knowledge should be promoted.  Article visualizations

Obtaining forest foods from timber trees in Cameroon: How far do people walk to collect fruits and caterpillars?

Approximately 61% of timber species in the Congo Basin also bear locally used non-timber forest products. Amongst these are fruits of Baillonella toxisperma, and edible caterpillars on Entandrophragma cylindricum and Erythrophleum suaveolens. Participatory mapping combining GPS coordinates and interviews was carried out with collectors in villages adjacent to logging concessions in Cameroon in order to: locate the trees from which men and women obtained these foods; determine the distances travelled by men and women to collect these wild resources; and assess the potential impacts of logging activities on local people’s access to these food resource

Brief Note A Radiocarbon-Dated Mammoth Site, Marion County, Ohio

Author Institution: Ohio Division of Geological Survey; Ohio Historical Society; Ohio State University-Mario

Comparison of intraoperative frozen section analysis for sentinel lymph node biopsy during breast cancer surgery for invasive lobular carcinoma and invasive ductal carcinoma

<p>Abstract</p> <p>Background</p> <p>Sentinel lymph node (SLN) biopsy is the standard of care for the surgical assessment of the axilla during breast cancer surgery. However, the diagnostic accuracy of intraoperative frozen section analysis for confirming metastatic involvement of SLNs in cases of invasive lobular carcinoma (ILC) versus that of invasive ductal carcinoma (IDC) has generated controversy secondary to a frequently low-grade cytologic appearance and an often discohesive pattern displayed by metastatic lymph nodes in ILC. In the current report, we present a comparison of intraoperative frozen section analysis for confirming the presence of metastatic disease within SLNs during breast cancer surgery for ILC and IDC.</p> <p>Methods</p> <p>We evaluated the results of 131 consecutive cases of ILC from 1997 to 2008 and 133 cases of IDC (selected by a random sequence generator program) from amongst 1163 consecutive cases of IDC from the same time period. All cases had at least one SLN that had both intraoperative frozen section analysis and confirmatory permanent section analysis performed.</p> <p>Results</p> <p>No statistically significant difference was found in the sensitivity (67% vs. 75%, P = 0.385), specificity (100% vs. 100%), accuracy (86% vs. 92%, P = 0.172), false negative rate (33% vs. 25%, P = 0.385), negative predictive value (81% vs. 89%, P = 0.158), and positive predictive value (100% vs. 100%) for frozen section analysis for confirming the presence of metastatic disease within SLNs during breast cancer surgery for ILC and IDC.</p> <p>Conclusion</p> <p>Since there was no statistically significant difference in sensitivity, specificity, accuracy, false negative rate, negative predictive value, and positive predictive value between frozen section analysis of SLNs for patients with ILC and IDC, the clinical accuracy of confirming metastatic involvement of SLNs on frozen section analysis for ILC should not be considered inferior to the clinical accuracy for IDC. Therefore, frozen section analysis of all SLNs during breast cancer surgery in patients with ILC should remain the standard of care in order to reduce the risk of the need of a later, separate axillary lymph node dissection.</p