14,868 research outputs found
The changing role of cell culture in the generation of transgenic livestock
Transgenesis may allow the generation of farm animals with altered phenotype, animal models for research and animal bioreactors. Although such animals have been produced, the time and expense involved in generating transgenic livestock and then evaluating the transgene expression pattern is very restrictive. If questions about the ability and efficiency of expression could be asked solely in vitro rapid progress could be achieved. Unfortunately, experiments addressing transcriptional control in vitro have proved unreliable in their ability to indicate whether a transgene will be transcribed or not. However, initial studies suggest that cell culture may be able to predict in vivo post-transcriptional events. We review these issues and propose that strategies which engineer the transgene integration site could enhance the probability for efficient expression. This approach has now become feasible with the development of techniques allowing animals to be generated from somatic cells by nuclear transfer. The important step in this procedure is the use of cells grown in culture as the source of genetic information, allowing the selection of specific transgene integration events. This technology which has dramatically increased the potential use of transgenic livestock for both agricultural and biotechnological applications, is based on standard cell culture methodology. We are now at the start of a new era in large animal transgenics
New functional redundancy approaches for attitude control thruster systems
Functional redundancy safeguards for inert gas attitude control thruster system
Circuit QED with a Flux Qubit Strongly Coupled to a Coplanar Transmission Line Resonator
We propose a scheme for circuit quantum electrodynamics with a
superconducting flux-qubit coupled to a high-Q coplanar resonator. Assuming
realistic circuit parameters we predict that it is possible to reach the strong
coupling regime. Routes to metrological applications, such as single photon
generation and quantum non-demolition measurements are discussed.Comment: 8 pages, 5 figure
Processing and Deploying the McDonnell Douglas Payload Assist Module (PAM)
This pap*r presents the flow of the operational PAM system from the time processing is started at the launch site through deployment from the Orbiters. It addresses the ground checkout activities, in-orbit operations including crew and ground personnel system evaluation and command activities, and PAM deployment from the Orbiter. Additionally, transfer orbit errors for two PAMs used on STS-5 are presented.
The PAM ground processing approach affords maximum assurance of a flight-ready PAM prior to mating the spacecraft and provides a cargo element that is fully verified as flightready before integration with the cargo integration test equipment (CITE) and the Orbiter. The PAM system design and on-board data displays give the astronauts the capability to evaluate the status of the PAM\u27s health and deploy the PAM/spacecraft without air-to-ground data or communications
Generation of spin-motion entanglement in a trapped ion using long-wavelength radiation
Applying a magnetic-field gradient to a trapped ion allows long-wavelength radiation to produce a mechanical force on the ion's motion when internal transitions are driven. We demonstrate such a coupling using a single trapped Yb+171 ion and use it to produce entanglement between the spin and motional state, an essential step toward using such a field gradient to implement multiqubit operations
Ground-state cooling of a trapped ion Using long-wavelength radiation
We demonstrate ground-state cooling of a trapped ion using radio-frequency (rf) radiation. This is a powerful tool for the implementation of quantum operations, where rf or microwave radiation instead of lasers is used for motional quantum state engineering. We measure a mean phonon number of n¯=0.13(4) after sideband cooling, corresponding to a ground-state occupation probability of 88(7)%. After preparing in the vibrational ground state, we demonstrate motional state engineering by driving Rabi oscillations between the |n=0⟩ and |n=1⟩ Fock states. We also use the ability to ground-state cool to accurately measure the motional heating rate and report a reduction by almost 2 orders of magnitude compared with our previously measured result, which we attribute to carefully eliminating sources of electrical noise in the system
Polyaryl ethers and related polysiloxane copolymer molecular coatings preparation and radiation degrdation
Poly(arylene ether sulfones) comprise a class of materials known as engineering thermoplastics which have a variety of important applications. These polymers are tough, rigid materials with good mechanical properties over a wide temperature range, and they are processed by conventional methods into products typically having excellent hydrolytic, thermal, oxidative and dimensional stability. Wholly aromatic random copolymers of hydroquinone and biphenol with 4.4 prime dichlorodiphenyl sulfone were synthesized via mechanical nucleophilic displacement. Their structures were characterized and mechanical behavior studied. These tough, ductile copolymers show excellent radiation resistance to electron beam treatment and retain much of the mechanical properties up to at least 700 Mrads under argon
The Ultrasensitivity of Living Polymers
Synthetic and biological living polymers are self-assembling chains whose
chain length distributions (CLDs) are dynamic. We show these dynamics are
ultrasensitive: even a small perturbation (e.g. temperature jump) non-linearly
distorts the CLD, eliminating or massively augmenting short chains. The origin
is fast relaxation of mass variables (mean chain length, monomer concentration)
which perturbs CLD shape variables before these can relax via slow chain growth
rate fluctuations. Viscosity relaxation predictions agree with experiments on
the best-studied synthetic system, alpha-methylstyrene.Comment: 4 pages, submitted to Phys. Rev. Let
Community Group-Based Models of Medication Delivery: Applicability to Cardiovascular Diseases.
The rising global burden of chronic non-communicable diseases (NCDs) has put a strain on healthcare systems globally, especially in low- and middle-income countries, which have seen disproportionate mortality rates due to non-communicable diseases. These deaths are in part due to challenges with medication adherence, which are compounded by lack of access to medication and weak community support systems. This paper aims to propose a potential solution using models of service delivery in HIV/AIDS, given the many similarities between NCD and HIV/AIDS. Models that have been particularly effective in HIV/AIDS are the community-based peer-support medication delivery groups: medication adherence clubs and community antiretroviral therapy (ART) groups. The positive outcomes from these models, including improved medication adherence and patient satisfaction, provide evidence for their potential success when applied to non-communicable diseases, particularly hypertension and cardiovascular disease
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