Drexel University

About: Drexel University is a education organization based out in Philadelphia, Pennsylvania, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 26770 authors who have published 51438 publications receiving 1949443 citations. The organization is also known as: Drexel & Drexel Institute.

Rain in Shallow Cumulus Over the Ocean: The RICO Campaign

Abstract: Shallow, maritime cumuli are ubiquitous over much of the tropical oceans, and characterizing their properties is important to understanding weather and climate. The Rain in Cumulus over the Ocean (RICO) field campaign, which took place during November 2004–January 2005 in the trades over the western Atlantic, emphasized measurements of processes related to the formation of rain in shallow cumuli, and how rain subsequently modifies the structure and ensemble statistics of trade wind clouds. Eight weeks of nearly continuous S-band polarimetric radar sampling, 57 flights from three heavily instrumented research aircraft, and a suite of ground- and ship-based instrumentation provided data on trade wind clouds with unprecedented resolution. Observational strategies employed during RICO capitalized on the advances in remote sensing and other instrumentation to provide insight into processes that span a range of scales and that lie at the heart of questions relating to the cause and effects of rain from shallow ...

MoS2 Nanosheets Vertically Aligned on Carbon Paper: A Freestanding Electrode for Highly Reversible Sodium‐Ion Batteries

Abstract: The development of sodium-ion batteries for large-scale applications requires the synthesis of electrode materials with high capacity, high initial Coulombic efficiency (ICE), high rate performance, long cycle life, and low cost. A rational design of freestanding anode materials is reported for sodium-ion batteries, consisting of molybdenum disulfide (MoS2) nanosheets aligned vertically on carbon paper derived from paper towel. The hierarchical structure enables sufficient electrode/electrolyte interaction and fast electron transportation. Meanwhile, the unique architecture can minimize the excessive interface between carbon and electrolyte, enabling high ICE. The as-prepared MoS2@carbon paper composites as freestanding electrodes for sodium-ion batteries can liberate the traditional electrode manufacturing procedure, thereby reducing the cost of sodium-ion batteries. The freestanding MoS2@carbon paper electrode exhibits a high reversible capacity, high ICE, good cycling performance, and excellent rate capability. By exploiting in situ Raman spectroscopy, the reversibility of the phase transition from 2H-MoS2 to 1T-MoS2 is observed during the sodium-ion intercalation/deintercalation process. This work is expected to inspire the development of advanced electrode materials for high-performance sodium-ion batteries.

Human hippocampal theta oscillations and the formation of episodic memories

Abstract: The importance of the hippocampal theta oscillation (4- 8 Hz) to memory formation has been well-established through studies in animals, prompting researchers to propose comprehensive theories of memory and learning that rely on theta oscillations for integrating infor- mation in the hippocampus and neocortex. Yet, empirical evidence for the importance of 4-8 Hz hippocampal theta oscillations to memory formation in humans is equivocal at best. To clarify this apparent inter- species discrepancy, we recorded intracranial EEG (iEEG) data from 237 hippocampal electrodes in 33 neurosurgical patients as they performed an episodic memory task. We identified two distinct patterns of hippo- campal oscillations, at 3 and 8 Hz, which are at the edges of the tra- ditional 4-8 Hz human theta band. The 3 Hz ''slow-theta'' oscillation exhibited higher power during successful memory encoding and was functionally linked to gamma oscillations, but similar patterns were not present for the 8 Hz ''fast-theta'' oscillation. For episodic memory, slow-theta oscillations in the human hippocampus appear to be analo- gous to the memory-related theta oscillations observed in animals. Both fast-theta and slow-theta oscillations exhibit evidence of phase syn- chrony with oscillations in the temporal cortex. We discuss our findings in the context of recent research on the electrophysiology of human memory and spatial navigation, and explore the implications of this result for theories of cortico-hippocampal communication. V C 2011 Wiley

A prospective randomized study of various irradiation doses and fractionation schedules in the treatment of inoperable non-oat-cell carcinoma of the lung. Preliminary report by the radiation therapy oncology group

Abstract: Preliminary analysis is presented of a prospective randomized study involving 365 patients with histologically proven unresectable non-oat-cell carcinoma of the lung treated with definitive radiotherapy. The patients were randomized to one of four treatment regimens: 4000 rad split course (2000 rad in five fractions one week, two weeks rest, and an additional 2000 rad in five fractions in one week) or 4000, 5000, or 6000-rad continuous courses in five fractions per week. Ninety to 100 patients were accessioned to each group. The one-year survival rate is 50% and the two-year survival rate, 25%. The patients treated with the split course have the lowest survival rate (10% at two years) in comparison with the other groups (range = 20–25%). The complete and partial local regression of tumor was 49% in patients treated with 4000 rad and 55% in the groups treated with 5000 and 6000 rad. For patients who achieved complete regression of the tumor following irradiation, the two-year survival rate is 40%, in contrast to 20% for those with partial regression, and no survivors among the patients with stable or progressive disease. The incidence of intrathoracic recurrence was 33% for patients treated with 6000 rad, 39% for those receiving 5000 rad, and 44–49% for those treated with a 4000-rad split or continuous course. At present, the data strongly suggest that patients treated with 5000 or 6000 rad have a better response, tumor control, and survival rate than those receiving lower doses. However, additional followup of patients at risk in each group will be necessary before a final conclusion is drawn. Patients with high performance status (Kornofsky index higher than 70), or with tumors in earlier stages (T1N2 or T3N0) have a two-year survival rate of approximately 40%, in comparison with 20% for other patients. The various irradiation regimens have been well tolerated, with complications being slightly higher in the 4000-rad split course group (10 severe and 2 life-threatening) and in the 6000-rad continuous course group (9 severe and 4 life-threatening). The most frequent complications have been pneumonitis, pulmonary fibrosis, and dysphagia due to transient esophagitis. Further investigation will be necessary before the optimal management of patients with bronchogenic carcinoma by irradiation is established.

An Overview of the Transmission Capacity of Wireless Networks

Abstract: This paper surveys and unifies a number of recent contributions that have collectively developed a metric for decentralized wireless network analysis known as transmission capacity. Although it is notoriously difficult to derive general end-to-end capacity results for multi-terminal or adhoc networks, the transmission capacity (TC) framework allows for quantification of achievable single-hop rates by focusing on a simplified physical/MAC-layer model. By using stochastic geometry to quantify the multi-user interference in the network, the relationship between the optimal spatial density and success probability of transmissions in the network can be determined, and expressed-often fairly simply-in terms of the key network parameters. The basic model and analytical tools are first discussed and applied to a simple network with path loss only and we present tight upper and lower bounds on transmission capacity (via lower and upper bounds on outage probability). We then introduce random channels (fading/shadowing) and give TC and outage approximations for an arbitrary channel distribution, as well as exact results for the special cases of Rayleigh and Nakagami fading. We then apply these results to show how TC can be used to better understand scheduling, power control, and the deployment of multiple antennas in a decentralized network. The paper closes by discussing shortcomings in the model as well as future research directions.