Detecting fractions of electrons in the high-TcT_c cuprates

We propose several tests of the idea that the electron is fractionalized in the underdoped and undoped cuprates. These include the ac Josephson effect, and tunneling into small superconducting grains in the Coulomb blockade regime. In both cases, we argue that the results are qualitatively modified from the conventional ones if the insulating tunnel barrier is fractionalized. These experiments directly detect the possible existence of the chargon - a charge $e$ spinless boson - in the insulator. The effects described in this paper provide a means to probing whether the undoped cuprate (despite it's magnetism) is fractionalized. Thus, the experiments discussed here are complementary to the flux-trapping experiment we proposed in our earlier work(cond-mat/0006481).Comment: 7 pages, 5 figure

Radiation- and Phonon-Bottleneck-Induced Tunneling in the Fe8 Single-Molecule Magnet

We measure magnetization changes in a single crystal of the single-molecule magnet Fe8 when exposed to intense, short (<20 $\mu$s) pulses of microwave radiation resonant with the m = 10 to 9 transition. We find that radiation induces a phonon bottleneck in the system with a time scale of ~5 $\mu$s. The phonon bottleneck, in turn, drives the spin dynamics, allowing observation of thermally assisted resonant tunneling between spin states at the 100-ns time scale. Detailed numerical simulations quantitatively reproduce the data and yield a spin-phonon relaxation time of T1 ~ 40 ns.Comment: 6 RevTeX pages, including 4 EPS figures, version accepted for publicatio

Seed Storage Reserves and Glucosinolates in Brassica rapa L. Grown on the International Space Station

Although plants are envisioned to play a central role in life support systems for future long-duration space travel, plant growth in space has been problematic due to horticultural problems of nutrient delivery and gas resupply posed by the weightless environment. Iterative improvement in hardware designed for growth of plants on orbital platforms now provides confidence that plants can perform well in microgravity, enabling investigation of their nutritional characteristics. Plants of B. rapa (cv. Astroplants) were grown in the Biomass Production System on the International Space Station. Flowers were hand-pollinated and seeds were produced prior to harvest at 39 days after planting. The material was frozen or fixed while on orbit and subsequently analyzed in our laboratories. Gross measures of growth, leaf chlorophyll, starch and soluble carbohydrates confirmed comparable performance by the plants in spaceflight and ground control treatments. Analysis of glucosinolate production in the plant stems indicated that 3-butenylglucosinolate concentration was on average 75% greater in flight samples than in ground control samples. Similarly, the biochemical make-up of immature seeds produced during spaceflight and fixed or frozen while in orbit was significantly different from the ground controls. The immature seeds from the spaceflight treatment had higher concentrations of chlorophyll, starch, and soluble carbohydrates than the ground controls. Seed protein was significantly lower in the spaceflight material. Microscopy of immature seeds fixed in flight showed embryos to be at a range of developmental stages, while the ground control embryos had all reached the premature stage of development. Storage reserve deposition was more advanced in the ground control seeds. The spaceflight environment thus influences B. rapa metabolite production in ways that may affect flavor and nutritional quality of potential space produce

Effect of Level Statistics on Superconductivity in Ultrasmall Metallic Grains

We examine the destruction of superconducting pairing in metallic grains as their size is decreased for both even and odd numbers of electrons. This occurs when the average level spacing d is of the same order as the BCS order parameter. The energy levels of these grains are randomly distributed according to random matrix theory, and we must work statistically. We find that the average value of the critical level spacing is larger than for the model of equally spaced levels for both parities, and derive numerically the probabilities $P_{o,e}(d)$ that a grain of mean level spacing d shows pairing.Comment: 12 pages, 2 PostScript files, RevTex format, submitted to PR

Empowering patient education on self-care activity among patients with colorectal cancer - a research protocol for a randomised trial

Background: Chemotherapy-induced side effects may have a negative effect on nutrition intake, thus increasing the risk of malnutrition and consequently, other serious complications for patients with cancer. The prevalence of malnutrition is common among patients with colorectal cancer. Nurse-led empowering education may have a positive effect on self-care activity in this patient group. Therefore, our purpose is to develop an empowering educational nursing intervention and test its effect on self-care activation and knowledge level among patients with colorectal cancer during chemotherapy. Secondary outcomes are quality of life and risk of malnutrition. Methods: An interdisciplinary expert group developed a face-to-face empowering educational intervention using teach-back method. A two-arm, single-centre, superiority trial with stratified randomisation (1:1) and pre-post measures will be used to assess the effect of the intervention compared to standard care. Patients (N = 40 + 40) will be recruited in one university hospital outpatient clinic in Finland. Eligibility criteria are adult patients diagnosed with colorectal cancer starting oral fluoropyrimidine or combination chemotherapy treatment. A registered nurse experienced in oncology will deliver the intervention 2 weeks after the first chemotherapy. Outcomes are measured before intervention (M0) and after a two-month follow-up period (M1). Discussion: This study will assess whether nurse-led empowering education using teach-back method is effective on self-care activity among patients with colorectal cancer. If the intervention has a positive effect, it may be implemented into patient education in a corresponding context.Peer reviewe

Electromechanics of charge shuttling in dissipative nanostructures

We investigate the current-voltage (IV) characteristics of a model single-electron transistor where mechanical motion, subject to strong dissipation, of a small metallic grain is possible. The system is studied both by using Monte Carlo simulations and by using an analytical approach. We show that electromechanical coupling results in a highly nonlinear IV-curve. For voltages above the Coulomb blockade threshold, two distinct regimes of charge transfer occur: At low voltages the system behave as a static asymmetric double junction and tunneling is the dominating charge transfer mechanism. At higher voltages an abrupt transition to a new shuttle regime appears, where the grain performs an oscillatory motion back and forth between the leads. In this regime the current is mainly mediated by charges that are carried on the grain as it moves from one lead to the other.Comment: 8 pages, 10 figures, final version to be published in PR

Rf-induced transport of Cooper pairs in superconducting single electron transistors in a dissipative environment

We investigate low-temperature and low-voltage-bias charge transport in a superconducting Al single electron transistor in a dissipating environment, realized as on-chip high-ohmic Cr microstrips. In our samples with relatively large charging energy values Ec > EJ, where EJ is the energy of the Josephson coupling, two transport mechanisms were found to be dominating, both based on discrete tunneling of individual Cooper pairs: Depending on the gate voltage Vg, either sequential tunneling of pairs via the transistor island (in the open state of the transistor around the points Qg = CgVg = e mod(2e), where Cg is the gate capacitance) or their cotunneling through the transistor (for Qg away of these points) was found to prevail in the net current. As the open states of our transistors had been found to be unstable with respect to quasiparticle poisoning, high-frequency gate cycling (at f ~ 1 MHz) was applied to study the sequential tunneling mechanism. A simple model based on the master equation was found to be in a good agreement with the experimental data.Comment: 8 pages, 6 figure