Measured Transfer Rates Research Articles

Relocation of DNA between layers of adhesive tape and other substrates

ABSTRACT Adhesive tape is a common piece of evidence that can contain a myriad of traces. Due to its adhesive properties, adhesive tape can potentially collect traces unrelated to the crime or relocate crime-relevant traces. This secondary transfer of traces can have crucial implications for the evaluation at the activity level. Therefore, this study investigated the secondary transfer of DNA between layers of adhesive tape and tape and other case- and laboratory-relevant substrates. A drop of diluted blood was deposited on different primary substrates (i.e. duct tape, metal, plastic, textile, nitrile gloves). Subsequently, the primary substrate was brought into contact with a secondary substrate, and DNA was collected from both surfaces to measure transfer rates. The highest transfer rates were detected between the adhesive side of the tape and plastic, whereas the lowest transfer rates were detected between the adhesive side and textile. It was shown that the adhesive readily collects DNA from plastic and nitrile gloves commonly used in the laboratory, which highlights the importance of working with DNA-free materials. Therefore, this study demonstrated the need for caution when interpreting traces on adhesive tapes, always taking possible situations of secondary transfer into account.

A review of experimental studies on contaminant transfer in energy exchangers (rp-1780)

This article presents a literature review on experimental studies for measuring gaseous contaminant transfer in different energy exchangers. The experimental methods, measured contaminant transfer rates and uncertainties (where available) for different gases are summarized, although most studies do not include any uncertainty analysis. The measured transfer rates vary between 0% and 75%, with uncertainties between 1% and 30%. The literature review shows that mechanisms for gaseous contaminant transfer in energy exchangers are air leakage, carryover, and phase change mechanisms such as: adsorption/desorption, condensation/evaporation, and absorption/evaporation. There is an established test methodology to quantify the gaseous contaminant transfer in energy exchangers due to air leakage and carryover; however, there is no method in the literature to quantify gaseous contaminant transfer due to the phase change mechanisms. Thus, a method to determine the contaminant transfer due to the phase change mechanisms is proposed and applied to the available literature data.

Estimating the transfer rates of bacterial plasmids with an adapted Luria-Delbrück fluctuation analysis.

To increase our basic understanding of the ecology and evolution of conjugative plasmids, we need reliable estimates of their rate of transfer between bacterial cells. Current assays to measure transfer rate are based on deterministic modeling frameworks. However, some cell numbers in these assays can be very small, making estimates that rely on these numbers prone to noise. Here, we take a different approach to estimate plasmid transfer rate, which explicitly embraces this noise. Inspired by the classic fluctuation analysis of Luria and Delbrück, our method is grounded in a stochastic modeling framework. In addition to capturing the random nature of plasmid conjugation, our new methodology, the Luria-Delbrück method ("LDM"), can be used on a diverse set of bacterial systems, including cases for which current approaches are inaccurate. A notable example involves plasmid transfer between different strains or species where the rate that one type of cell donates the plasmid is not equal to the rate at which the other cell type donates. Asymmetry in these rates has the potential to bias or constrain current transfer estimates, thereby limiting our capabilities for estimating transfer in microbial communities. In contrast, the LDM overcomes obstacles of traditional methods by avoiding restrictive assumptions about growth and transfer rates for each population within the assay. Using stochastic simulations and experiments, we show that the LDM has high accuracy and precision for estimation of transfer rates compared to the most widely used methods, which can produce estimates that differ from the LDM estimate by orders of magnitude.

A High-Performance and Hardware-Efficient PCIe Transmission for a Multi-Channel Video Using Command Caching and Dynamic Splicing on FPGA

With the increasing requirements of transmitting larger amounts of diverse video and image data, the PCI express (PCIe) interface has been extensively used in high-speed digital systems for multimedia processing and communication. However, the existing PCIe transmission methods are not efficient to transmit multi-channel videos on FPGA processors, as they waste PCIe bandwidth and hardware resources. In this paper, an efficient PCIe transmission method for multi-channel video is presented on an FPGA processor. First, to reduce the programmed I/O (PIO) write latency, the command caching method is adopted. The traditional DMA descriptors are transformed into DMA commands, which are smaller, and the command buffer is used to store these commands. Second, a dynamic splicing mechanism is proposed for data transmission and commands the scheduling separately. The multi-type data is transmitted concurrently in this dynamic splicing mechanism. Moreover, the adjacent commands are spliced into one command, which reduces the DMA initiation times. Finally, the direct kernel memory access technique and timer self-feedback monitor technique are applied to improve the transmission efficiency and enhance the system reliability. The experimental results show that the transmission efficiency of the proposed method is increased by nearly 30% compared with other conventional methods, and the highest measured transfer rate is 1631 Mbytes/s on write and 1582 Mbytes/s on read, which reaches 84.4% of the theoretical maximum.

Conjugation efficiency depends on intra and intercellular interactions between distinct plasmids: Plasmids promote the immigration of other plasmids but repress co-colonizing plasmids

Conjugative plasmids encode the genes responsible for the synthesis of conjugative pili and plasmid transfer. Expression of the conjugative machinery (including conjugative pili) may be costly to bacteria, not only due to the energetic/metabolic cost associated with their expression but also because they serve as receptors for certain viruses. Consequently, the presence of two plasmids in the same cell may be disadvantageous to each plasmid, because they may impose a higher fitness cost on the host. Therefore, plasmids may encode mechanisms to cope with co-resident plasmids. Moreover, it is possible that the transfer rate of a plasmid is affected by the presence of a distinct plasmid in the recipient cell. In this work, we measured transfer rates of twelve natural plasmids belonging to seven incompatibility groups in three situations, namely when: (i) donor cells contain a plasmid and recipient cells are plasmid-free; (ii) donor cells contain two unrelated plasmids and recipient cells are plasmid-free; and (iii) half of the cells contain a given plasmid and the other half contain another, unrelated, plasmid. In the third situation, recipient cells of a plasmid are the donor cells of the other plasmid. We show that there are more negative interactions (reduction of a plasmid's conjugative efficiency) between plasmids if they reside in the same cell than if they reside in different cells. However, if plasmids interacted intercellularly, the transfer rate of one of the plasmids was often higher (when the unrelated conjugative plasmid was present in the recipient cell) than if the recipient cell was plasmid-free – a positive effect. Experimental data retrieved from the study of mutant plasmids not expressing conjugative pili on the cell surface suggest that positive effects result from a higher efficiency of mating pair formation. Overall, our results suggest that negative interactions are significantly more frequent when plasmids occupy the same cell. Such interactions may determine how antibiotic resistance disseminates in bacterial populations.

Electron Transfer from Single Semiconductor Nanocrystals to Individual Acceptor Molecules

This Letter reports the measurement of photoinduced electron-transfer rates from individual CdSe/CdS nanocrystals, or quantum dots (QDs), to methyl viologen acceptor molecules adsorbed on the QD surfaces, using time-resolved photoluminescence at the single-nanocrystal level. For each QD measured, the electron-transfer rate is constant over time, and the photoluminescence blinking dynamics are independent of the measured transfer rate. The total electron-transfer rate is distributed in discrete, constant increments, corresponding to discrete numbers of adsorbed molecules on each QD. The results thus validate previous assumptions that viologen molecules adsorb independently on QD surfaces and that the total electron-transfer rate from a single QD to multiple molecules on its surface is simply the sum of the transfer rates to the individual molecules. The measurement provides an optical method to count the number of active acceptor molecules bound to a single nanocrystal and opens up new possibilities for me...

Prediction and improvement of the solid particles transfer rate for the bulk handing system design of offshore drilling vessels

Numerous experiments with a scaled pilot facility were carried out to compare the relative bulk transfer performance of three special devices for applications to drilling systems. The pipe diameter for bulk transportation was 3 in., which corresponds to around half of the actual system dimensions. Two different pressures, 3 and 4 bar, were considered to check the relative performance under different pressure conditions at a bulk storage tank. And to make a practical estimation method of the bulk transfer rate at the early design stages of the bulk handling system, a series of experiments were conducted for real scaled bulk handing systems of two drilling vessels. The pressure drops at each pipe element as well as the bulk transfer rates were measured under different operating conditions. Using the measured results, the friction factor for each pipe element was calculated and a procedure for transfer rate estimation was developed. Compared to the measured transfer rate results for other drilling vessels, the estimated transfer rates were within a maximum 15% error bound.

State-Mixing of nS Rydberg Atoms in an External Electric Field

State-mixing effect of ultracold nS cesium Rydberg atoms in an external electric field is investigated in a magneto-optical trap. Populated high-l Rydberg atoms due to the state-mixing through avoided crossings are measured with a state-selective field ionization technique. The measured transfer rates of high-l states increase with the electric field and get to the maximum at the field of about 3.0 V/cm for 49S1/2 Rydberg state, and show decrease behavior when the electric field increases further. The decrease behavior of the transfer rate is explained with the slower m-mixing effect caused by decreasing dipole–dipole interactions between high-l Rydberg atoms. During the m-mixing process the ultracold plasma is formed by the Penning ionization.

Collisional population transfer in trappedYb+ions

Long-lived metastable states of Yb+ ions are used for atomic frequency standards, precision measurements, and quantum information research. The effect of population trapping and transfer in these states must be well understood. We report here the transfer of Yb+ ions into the long-lived {sup 2}F{sub 7/2} state by means of collisions between He buffer gas and Yb+ ions held in a linear Paul trap. Transfer rates were measured as functions of buffer-gas pressure and repump-laser power, and the collisional population transfer rates were extracted. The measured transfer rate coefficients are 8.32(75)x10-11 and 8.65(33)x10-11 cm3/s for the collisional processes {sup 2}P{sub 1/2}{yields}{sup 2}D{sub 5/2} and {sup 2}D{sub 3/2}{yields}{sup 2}F{sub 7/2}, respectively.

Design and evaluation of a hardware/software FPGA-based system for fast image processing

We evaluate the performance of a hardware/software architecture designed to perform a wide range of fast image processing tasks. The system architecture is based on hardware featuring a Field Programmable Gate Array (FPGA) co-processor and a host computer. A LabVIEW™ host application controlling a frame grabber and an industrial camera is used to capture and exchange video data with the hardware co-processor via a high speed USB2.0 channel, implemented with a standard macrocell. The FPGA accelerator is based on a Altera Cyclone II chip and is designed as a system-on-a-programmable-chip (SOPC) with the help of an embedded Nios II software processor. The SOPC system integrates the CPU, external and on chip memory, the communication channel and typical image filters appropriate for the evaluation of the system performance. Measured transfer rates over the communication channel and processing times for the implemented hardware/software logic are presented for various frame sizes. A comparison with other solutions is given and a range of applications is also discussed.

Evaluation of reproductive potential after intracytoplasmic sperm injection of varied human semen tested by antiacrosomal antibodies

To determine whether varied human spermatozoa, as detected with monoclonal antibodies against acrosomal proteins, have an influence on fertilization, transfer, pregnancy, and implantation rates when intracytoplasmic sperm injection is used. A retrospective study. A private IVF center and academic research laboratory. One thousand two hundred forty men participating in the intracytoplasmic sperm injection program. Sperm were divided into seven groups: oligozoospermia, oligoasthenozoospermia, and oligoasthenoteratozoospermia and fresh and frozen-thawed epididymal and fresh and frozen-thawed testicular sperm. Fertilization, transfer, pregnancy, and implantation rates were recorded in each category. Sperm were tested with antibodies for detection of the of the sperm acrosome. Fertilization, transfer, pregnancy and implantation rates, and percentage of acrosome-reacted cells. The fertilization rate and statistical evaluation showed differences between morphologically normal and pathological sperm and other groups. The freezing-thawing procedure had no influence on the fertilization of testicular sperm, but epididymal frozen-thawed sperm had a higher fertilization rate. Immunofluorescence proved decreasing sperm quality in all groups compared with the control group. This difference is not manifested in other parameters (transfer, pregnancy, implantation rates). The spermatozoa with varied semen characteristics and good quality, also detected with specific antibodies, gave the best fertilization rates. The paternal effect is not proved in other parameters.

Deriving the Signal-to-Noise Ratio Probability of Error and Performance Measure Matrices for Distribution Line Carrier Signals Propagation (Using Bus Impedance Approach)

The automated distribution system using distribution line carrier (DLC) needs a two way communication between the various controlled terminals and the main substation. Digital data should be transmitted over the distribution power lines from the main substation to the transceivers in the distribution system and vice versa. The distribution system is a hostile medium for data transmission [i.e., high noise levels and standing wave patterns with low voltage nodes (as a result of signal reflections in the system)]. This hostility leads to low signal-to-noise ratio (SNR) locations and subsequently to high probability of bit error at these locations. The bus impedance matrix was developed for medium voltage distribution system. An actual medium voltage distribution line was tested. The actual measurements of the tested line verified the validity of the derived equations. The above mentioned line with the addition of a branch is used as an example in this paper. This paper derives (SNR) probability of bit error and performance measure transfer rate of information bits (TRIB) matrices of any DLC system starting from the bus impedance matrix.

Identifying the Pathways of Energy Transfer between Carotenoids and Chlorophylls in LHCII and CP29. A Multicolor, Femtosecond Pump−Probe Study

Spectral and kinetic information on energy transfer from carotenoids (Cars) to chlorophylls (Chls) within light-harvesting complex II (LHCII) and CP29 was obtained from femtosecond transient absorption study by using selective Car excitation (489 and 506 nm) and detecting the induced changes over a wide spectral interval (460−720 nm). By examining the evolution of entire spectral bands rather than looking at a few single traces, we were able to identify the species (pigments and/or electronic states) which participate in the energy flow, as well as the lifetimes and quantum yields of individual processes. Hence, it was found that the initially excited Car S2 state decays very fast, with lifetimes of 70−90 fs in CP29 and 100 ± 20 fs in LHCII, via two competing channels: energy transfer to Chls (60−65%) and internal conversion to the lower, optically forbidden S1 state (35−40%). In CP29, the energy acceptors are exclusively Chls a, while in LHCII, this is only valid for lutein and violaxanthin. In the latter case, neoxanthin transfers energy mostly to Chls b. In both complexes, ca. 15−20% of the initial Car excitations are transferred to Chls a via the S1 level, with a time constant of around 1 ps, thus bringing the total Car−Chl transfer efficiency to ca. 80%. Given the yield of this process and the large difference between the transfer time and the intrinsic S1 lifetime (∼20 ps), it seems that lutein is the only species active on this pathway. From the measured transfer rates, we estimated that a coupling of 280−330 cm-1 drives the transfer via the S2 route, while a coupling value of around 100 cm-1 was estimated for the S1 transfer. The Car S2 state is coupled to both Qx and Qy states of the Chl through a Coulombic mechanism; from the available structural information, we estimated the dipole−dipole contribution to be 450−500 cm-1. The S1 state is coupled to the Chl a Qy transition via an exchange and/or a Coulombic mechanism.

Construction of a compact DAQ-system using DSP-based VME modules

A data-acquisition (DAQ) system based upon the SRARC digital-signal-processor (DSP) has been developed. Either one or two DSPs are mounted onto VME boards, WS2126. VME-to-VME data transfer utilizes SHARC links (33.7 MB/s of measured transfer rate), routed onto a front panel of the WS2126 by I/O piggy pack modules, WS9002. The system has been designed for readout of 81,920 FADC (flash analog-to-digital converter) channels at a maximum trigger rate of 500 Hz. This system could be accomplished in a compact setup of four FADC readout VME crates and one master-control VME crate (for event-building and run-control). The system was tested for readout of the BELLE Si vertex detector (SVD).

Multiple paths protocol for a cluster type network

Nowadays we can access the Internet by carrying a portable computer and using wireless communication. The wireless network with personal handy phone system (PHS) and portable cellular telephone has only rates of tens of Kbps to a few Mbps. Compared with the cable network, the transfer rate cannot generally satisfy a highly developed communication service such as large file transfer and real-time communications. This paper proposes a protocol, SHAKE, for sharing multiple paths in a cluster type network that is a kind of LAN in which some mobile hosts temporarily connect mutually. SHAKE provides the functions for composing a cluster type network, and dispersing traffic efficiently by measuring transfer rate and round-trip time. As a mobile host has only a low transfer capacity for individuals to communicate with the outside, if whole capacities of other hosts which compose a cluster type network are shared, we can get larger transfer capacity and satisfy the required communication services. Copyright © 1999 John Wiley & Sons, Ltd.

Dynamic Mixing and Oxygen Transfer in Small, Airlift Loop Bioreactors: Model and Experimental Verification

AbstractA mechanistic model for mixing and mass transfer in both airlift bubble column and loop bioreactors is described. The model is a useful design tool to improve oxygen‐transfer characteristics. It is shown that the model fits mixing and mass‐transfer experimental data closely. The model confirms that the overall oxygen‐transfer coefficient in the riser of a loop airlift fermentor is similar to that in bubble columns and that lower measured transfer rates are due solely to the dead volume in the downcomer. The effects of parameters such as mass‐transfer coefficient, aeration rate, dispersion coefficient, sparger rotation speed, and liquid circulation velocity are presented in terms of both the liquid‐ and gas‐phase oxygen concentrations.

In vitro evidence that phospholipid secretion into bile may be coordinated intracellularly by the combined actions of bile salts and the specific phosphatidylcholine transfer protein of liver.

Using model systems, we explored a potential function of hepatic phosphatidylcholine transfer protein to extract biliary-type phosphatidylcholines from intracellular membranes (e.g., smooth endoplasmic reticulum) and deliver them to canalicular plasma membranes where biliary secretion occurs. We measured transfer rates of parinaroyl phosphatidylcholine, a naturally fluorescent phospholipid, from small unilamellar vesicles composed of sn-1 palmitoyl, sn-2 parinaroyl phosphatidylcholine, and egg yolk phosphatidylcholine (molar ratio 75:25) wherein the fluorophore is self-quenched to small unilamellar vesicles composed of phosphatidylethanolamine, sphingomyelin, phosphatidylserine, phosphatidylinositol, and cholesterol (molar ratios 22:22:10:8:38) representing model microsomal and canalicular plasma membranes, respectively. Following addition of phosphatidylcholine transfer protein (purified from bovine liver), fluorescence intensity increased exponentially indicating net phosphatidylcholine transfer from donor to acceptor vesicles. Submicellar concentrations of a wide hydrophobicity range of common and uncommon taurine and glycine conjugated bile salts species (anionic steroid detergent-like molecules), sodium taurofusidate (a conjugated fungal bile salt analog), and sodium dodecyl sulfate and octylglucoside, anionic and nonionic straight chain detergents, respectively, markedly stimulated phosphatidylcholine transfer protein activity. This 40-115-fold effect was most pronounced for the common bile salts and correlated positively with bile salt hydrophobicity. Thermodynamic analysis of net transfer revealed that the rate-limiting step was extraction of phosphatidylcholine molecules from donor vesicles and that bile salts facilitated their capture by enhancing both phosphatidylcholine transfer protein binding as well as perturbing phospholipid packing in vesicle bilayers.(ABSTRACT TRUNCATED AT 250 WORDS)

The mechanism of Tm to Ho energy transfer in LiYF4

The energy transfer properties of the Tm, Ho:LiYF4 are examined, and special attention is given to the Tm(3F4) to Ho(5I7) transfer dynamics and equilibration. The measured transfer times are compared with the values calculated on the basis of the static Forster-Dexter and the migration-assisted Burshtein energy transfer models (which require only spectral information and rare-earth concentrations as input data). The detection of anomalously fast measured transfer rates at high Tm doping levels is interpreted within the context of percolation theory, since migration pathways from the excited Tm ion to a Ho ion must necessarily exist above a particular threshold concentration. Lastly, it is suggested that the use of low Tm concentrations below the percolation threshold may serve to minimize the Auger upconversion losses, and also will shift the excited-state equilibrium to the Ho population; this type of scenario requires that the Tm ions be pumped directly into the 3F4 state with 1.68 mu m InGaAs diode sources.

PCDD/F in an agricultural food chain Part 1: PCDD/F mass balance of a lactating cow

A mass balance was conducted of the PCDD/F fluxes into and out of a lactating cow in an unmodified environment. Feed was found to be responsible for virtually all of the cow's PCDD/F exposure. Approximately 20% of the 2,3,7,8-Cl 4DD toxic equivalents taken up by the cow was excreted in the milk. The measured transfer rates for a cow in a natural state generally agreed well with the results from feeding experiments in the literature. The digestive tract resorption of PCDD/F decreased with increasing degree of chlorination. Both the feces and the milk were important routes for the excretion of persistent PCDD/F isomers.

Facilitated transport of benzylpenicillin through immobilized liquid membrane

AbstractThe rate of benzylpenicillin transport, as an ionic pair with a tetrabutyl ammonium cation, from aqueous media through a liquid membrane consisting of n‐decanol supported in a porous Teflon membrane has been investigated as a function of the chemical composition of the system and the hydrodynamic conditions at 25°C. The measured transfer rates have been explained in terms of the diffusion of the ionic pair species through the liquid membrane. The results are in agreement with theoretical predictions and it is demonstrated that the transport of benzylpenicillin takes place against a concentration gradient.