Reconstruction of lake-level and climate changes in Lake Qarun,Egypt, during the last 7000 years

Sediment cores from Lake Qarun provide a record of mid-late Holocene climatic changes in Northern and Eastern Africa as well as environmental changes due to the activities of ancient Egyptians. We used sedimentological, mineralogical, and geochemical analyses of the cores to investigate long-term variations in lake level due to changing hydrologic inputs. An age model based on three paired ¹⁴C and paleomagnetic measurements suggests that the base of the sediment cores is as old as ∼ 5000 B.C.E. Geochemical analyses indicated that lake sediments were derived from Nile floods with an admixture of Saharan sand. Laminated endogenic carbonate-rich clayey silt lithofacies with benthic diatoms are indicative of relatively low lake levels, saline waters and dry conditions; massive lithofacies with planktonic diatom species are indicative of relatively high lake levels, fresh waters and humid conditions. Faintly laminated clayey silt lithofacies suggest intermediate conditions. Variations in lithology as well as diatom composition suggest that the lake level has varied from relatively high levels in its early history to lower levels in later years although there have been numerous cycles in water level over the past 7000 years. A combination of climate changes in the source area of the Nile River as a result of monsoon dynamics; climatic changes in the setting area of the Lake Qarun; and human activities through the dynasties in Egypt produced these variations in lake level.     

Numerical Analysis of the Boundary Scattering Effect on Transport Properties in Bi-Sb Nanowires

In this study, we have numerically analyzed the transport properties of Bi-Sb nanowires, taking into account wire boundary scattering. Wire boundary scattering slightly decreased the Seebeck coefficient of Bi-Sb nanowires. This effect is due to the observation that boundary scattering and the mobility ratio of L-point electrons to T-point holes in the nanowires are smaller than those in bulk Bi-Sb because the wire boundary scattering suppresses the mobilities of L-point electrons and heavy holes. The largest Seebeck coefficient for all wire diameters was obtained when the Sb concentration was 5 at.%. The effective mass approached zero near 5 at.% Sb, and the small effective mass led to a large subband shift in each band. Thus, a small effective mass enhances the quantum effect at a fixed wire diameter, even if wire boundary scattering is taken into account.     

The influence of dopant species on thermal stability of NiSi film

We investigated the relationship between thermal stability of NiSi films and the implanted dopant species on Si substrates. The most stable NiSi layer appeared on Boron-implanted Si substrate, where the formation of pseudo-epitaxial transrotational structure was observed, just in case that the dose of boron is more than 5e15 atoms/cm². This unique crystallographic orientation of NiSi film on Boron-implanted substrate is a key role of thermal stability because thermal stress at grain boundary can be diminished by peculiar arrangement of transrotational domains, owing to the anisotropy in coefficient of thermal expansion (CTE) of NiSi.     

Space Division Multiple Access (SDMA): An Editorial Introduction

Wireless Personal Communications -     

Evaluation of Chinese hamster ovary cell stability during repeated batch culture for large-scale antibody production

Pharmaceutical manufacturing plants can be operated continuously for several months. It is therefore important to use cells with long-term stability for the production of active ingredients. We investigated the reliability and long-term stability of an antibody-producing cell line. A recombinant Chinese hamster ovary (CHO) cell line was cultivated in spinner flasks and reactors, including a practical production-scale reactor (1600 L), for 109 days to produce monoclonal antibodies against the HM1.24 antigen. During cultivation, the cells remained stable and there was an increase in the rate of cell proliferation, yielding viable cells at high density. A decrease in cell-specific productivity was associated with this increase in the rate of cell proliferation. The cells were genetically stable and other measures of cellular function remained consistent throughout the cultivation period.     

On a Distributed Cognitive MAC Protocol for IEEE 802.11s Wireless Mesh Networks

A distributed frequency agile medium access control (MAC) extension to the IEEE 802.11s for the next generation wireless mesh networks is proposed. The introduced protocol enhancements are capable of concurrent deployment of existing frequency opportunities in order to coordinate simultaneous data transmissions. The root concept is mainly based on the deployment of well-known ISM frequency bands, where the legacy 802.11-based wireless equipments operate, as the common control channel in order to establish contemporaneous transmissions. We apply the aforementioned key concept to the IEEE 802.11s common channel framework to attain two important goals: To improve the channel utilization using the concept of cognitive radio, and to lower the access delay. Through extensive event-driven simulations, taking into account primary user appearance in non-ISM frequency bands, performance of the proposed MAC enhancement is evaluated showing its higher efficiency compared to the existing solutions, in addition to its better wireless medium management.     

Defect reduction in Cu dual damascene process using short-loop test structures

This paper outlines the defect reduction measures performed during the development of a 130-nm Cu dual-damascene process. The test methodology, using short-loop test structures, included defect tracing, overlaying defect data and electrical measurement data, physical analyses based on these results, and analyses of defect size distribution. While the defect size distributions for large-scale integration processes are considered to depend on x/sup -k/, the distribution for the Cu dual-damascene process is found to be different and is instead characterized by a cumulative distribution described by the composition of several Lorentzian functions. Using these procedures, defect densities were successfully reduced by 50% in half the time taken previously and without the need for actual products.     

A DC-powered Josephson logic family that uses hybrid unlatchingflip-flop logic elements (Huffles)

This paper describes the development of a dc-powered Josephson logic family that uses hybrid unlatching flip-flop logic elements (Huffles). The Huffle circuit used in this study is modified by adding a parallel resistor to the original Hebard-type Huffle circuit. Analysis of the circuit's operation shows that the undesirable hung-up phenomena are prevented by this modification. Based on the result of the analysis, the circuit's parameters are derived and a typical operating margin of ±26% is obtained. Besides AND/OR operations using a threshold logic operation, two-input exclusive OR (XOR), two-input multiplexor (MUX), and three-input majority (MAJ) operations are realized using a Huffle gate in which 2-Josephson-interferometers (2JI) in the standard Huffle gate are replaced by stacked-2JI's. Thus, a Huffle logic family, formed from NOT, AND, OR, XOR, MUX, MAJ, and flip-flop (FF), are constructed. By using this Huffle logic family, a 6-b arithmetic logic operating unit (ALU), a 6-b analog-to-digital converter (ADC), and a 6-b gray-to-binary converter (GBC) have been successfully operated. During high-speed testing, a 1-b comparator was operated up to an input bandwidth of 6 GHz