320 research outputs found
Studies relating to the Ă-disintegration of some heavy elements, using magnetic spectrometer of high collecting power.
In recent years the improved methods of nuclear
spectroscopy have provided an increasing body of
information about the modes of disintegration of both
naturally occurring and artificially produced radio-elements.
This has led to the development of nuclear
models which are capable of interpreting the nuclear
data in terms of the properties of the nuclear structure
with some success. Spins and parities are
assigned to nuclear energy levels, and selection rules
have been formulated by which the observed decay
properties can be explained fairly consistently. The
properties of the nuclear levels can be established
from a variety of measurements. In Ă- and Îł -ray
spectroscopy these include the relative intensities
and high energy end-points of the partial components of
the Ă-speetrum, determined by the method of Fermi
analysis from the continuous spectrum produced in the
(Ă-decay of a parent nucleus, and the intensities,
lifetimes and multipole nature of subsequent Îł-
transitions between higher and lower lying energy
levels in the daughter nucleus. These Îł-transitions
give rise to internal conversion electrons which are
superimposed as mono-energetic lines on the continuous
Ă-spectrum. The internal conversion electrons are
formed through the interaction of a Îł-ray of energy
EÎł with an electron of the K, L, -shell of the
product nucleus. The energy EĂ of the electrons
emitted from the shell is given by EĂ = EÎł - Eâ (or
Eâ ), where Eâ' (or Eâ', ) is the binding
energy of the K, L, -shell electrons in the proÂŹ
duct atom. It is customary to speak of the conversion
of the Îł-rays although it is now recognised that the
electron emission is a competitive decay process resulting
from the mutual interaction of the overlapping
nuclear and electronic wave functions. The relative
conversion efficiencies for Îł-rays in the different
shells or sub-shells and the ratio of conversion electrons
to photon de-excitations (the conversion coefficients)
in an atom depend, along with their lifetimes,
on the energy and multipole nature of the radiation.
The absolute intensities of the conversion lines,
together with theoretically or experimentally determined
conversion coefficients, permit the total intensities
of y-transitions to be calculated relative to the
total number of Ă-transitions. The energies and
intensities of the Ă- and Îł-transitions in conjunction
with Îł-ray studies may then form the basis of a
complete disintegration scheme, while measurements of the
coincidence of Ă- and Îł-transitions may be made to
decide conclusively between possible level schemes.
The present investigations on the electron spectrum
of heavy radio-elements were undertaken with a
magnetic spectrometer and provide information on the
energies and intensities of Ă-transitions and internally
converted Îł-transitions. The spectrometer has
recently been equipped with a Îł-ray detector which,
with the possibility of making Ă-Îł coincidence
measurements, will extend its capabilities in future
studies.
The spectrometer was designed by Richardson (1, 2)
and the performance has been investigated and described,
by Braid and Richardson (3). A description of the
spectrometer is given in Chapter 3 but those features
that distinguish it from conventional Ă-particle
spectrometers will be mentioned here, together with
those properties that determine the type of radio-element
that can be most profitably investigated
Processing LiDAR Data to Predict Natural Hazards
ELF-Base and ELF-Hazards (wherein 'ELF' signifies 'Extract LiDAR Features' and 'LiDAR' signifies 'light detection and ranging') are developmental software modules for processing remote-sensing LiDAR data to identify past natural hazards (principally, landslides) and predict future ones. ELF-Base processes raw LiDAR data, including LiDAR intensity data that are often ignored in other software, to create digital terrain models (DTMs) and digital feature models (DFMs) with sub-meter accuracy. ELF-Hazards fuses raw LiDAR data, data from multispectral and hyperspectral optical images, and DTMs and DFMs generated by ELF-Base to generate hazard risk maps. Advanced algorithms in these software modules include line-enhancement and edge-detection algorithms, surface-characterization algorithms, and algorithms that implement innovative data-fusion techniques. The line-extraction and edge-detection algorithms enable users to locate such features as faults and landslide headwall scarps. Also implemented in this software are improved methodologies for identification and mapping of past landslide events by use of (1) accurate, ELF-derived surface characterizations and (2) three LiDAR/optical-data-fusion techniques: post-classification data fusion, maximum-likelihood estimation modeling, and hierarchical within-class discrimination. This software is expected to enable faster, more accurate forecasting of natural hazards than has previously been possible
Activity of artemether and OZ78 against triclabendazole-resistant Fasciola hepatica
Triclabendazole is the drug of choice against Fasciola hepatica infections in humans and animals. However, parasite resistance against triclabendazole is spreading in the veterinary field, and there are no drugs of comparable activity currently available for the treatment and control of fascioliasis. We investigated the efficacy of single oral doses of artemether and OZ78 against adult triclabendazole-resistant F. hepatica harboured in rats, and compared the results with triclabendazole administered at two different doses. Single oral doses of 100 mg/kg OZ78 and 200 mg/kg artemether resulted in worm burden reductions of 100%. Whereas a single 10 mg/kg dose of triclabendazole achieved a worm burden reduction of only 4.0%, a five-fold higher dose yielded a significant worm burden reduction of 60.9%. However, the lower dose of triclabendazole administered to rats harbouring a triclabendazole-sensitive F. hepatica isolate resulted in a worm burden reduction of 95.3%. Our findings confirm that artemether and OZ78 possess good fasciocidal properties, even against a triclabendazole-resistant F. hepatica isolate, and hence these drugs might become useful in areas where triclabendazole resistance is commo
Testing albendazole resistance in Fasciola hepatica: validation of an egg hatch test with isolates from South America and the United Kingdom
The main goal of the current work was to develop and validate an in vitro fluke egg hatch test, as a method for the detection of albendazole (ABZ) resistance in the liver fluke, Fasciola hepatica. Fluke eggs (200/ml, n ÂŒ 5) from six different isolates were used in the current experimental work. They were obtained from different geographical locations and named Cullompton (UK), CEDIVE (Chascomus, Argentina), INTA-Bariloche (Bariloche, Argentina), Rubino (Uruguay), Cajamarca (PeruÂŽ ) and RıŽo Chico (Catamarca, Argentina). The fluke eggs were incubated (258C) for a 12-h period in the presence of either ABZ or its sulphoxide metabolite (ABZ.SO) (5, 0.5 or 0.05 nmol/ml). Untreated eggs were incubated as a control. Incubated eggs (with or without drug present) were kept in darkness at 258C for 15 days. Afterwards, the trematode eggs were exposed to daylight over a 2-h period. Hatched and unhatched eggs were evaluated using an optical microscope, and the ovicidal activity was assessed for each fluke isolate. A very low ovicidal activity (#13.4%) was observed in the ABZ-resistant CEDIVE isolate for both ABZ and ABZ.SO. Conversely, in the INTA-Bariloche and RıŽo Chico isolates, which are suspected to be susceptible to ABZ, ovicidal activities $ 70.3% were observed after incubation with ABZ at the lowest concentration tested (0.05 nmol/ml). This finding correlates with that previouslyFil: Canevari, JosĂ©. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de FisiopatologĂa. Laboratorio de FarmacologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Tandil. Centro de Investigacion Veterinaria de Tandil; ArgentinaFil: Ceballos, Laura. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de FisiopatologĂa. Laboratorio de FarmacologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Tandil. Centro de Investigacion Veterinaria de Tandil; ArgentinaFil: Sanabria, Rodrigo Eduardo Fabrizio. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Departamento de Clinica. Centro de Diagnostico e Investigaciones Veterinarias; ArgentinaFil: Romero, Jorge Roberto. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Departamento de Clinica. Centro de Diagnostico e Investigaciones Veterinarias; ArgentinaFil: Olaechea, FermĂn. Instituto Nacional de TecnologĂa Agropecuaria. Centro Regional Patagonia Norte. EstaciĂłn Experimental Agropecuaria San Carlos de Bariloche; ArgentinaFil: Ortiz, Pedro. Universidad Nacional de Cajamarca. Facultad de Ciencias Veterinarias; PerĂșFil: Cabrera, MarĂa. Universidad Nacional de Cajamarca. Facultad de Ciencias Veterinarias; PerĂșFil: Gayo, Valeria. Instituto DILAVE "Miguel C. Rubino"; UruguayFil: Fairweather, Ian. The Queenâs University of Belfast. Medical Biological Centre. School of Biological Sciences. Parasite Therapeutics Research Group; ArgentinaFil: Lanusse, Carlos Edmundo. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de FisiopatologĂa. Laboratorio de FarmacologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Tandil. Centro de Investigacion Veterinaria de Tandil; ArgentinaFil: Alvarez, Luis Ignacio. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de FisiopatologĂa. Laboratorio de FarmacologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Tandil. Centro de Investigacion Veterinaria de Tandil; Argentin
Control of Nematodirus spp. infection by sheep flock owners in Northern Ireland
Publication history: Accepted - 10 October 2017; Published online - 19 October 2017.Background
To address a lack of information on the control of ovine helminth parasites in Northern Ireland (NI), a number of research projects have been undertaken, dealing with gastrointestinal nematodes, tapeworms and liver fluke. This investigation concerns Nematodirus and concentrates on three aspects of disease: farm management strategies for its control, derived from the results of a Questionnaire; the efficacy of treatment used by farmers, as determined by a coprological survey; and the hatching requirements of Nematodirus eggs, that is, whether prolonged chilling is a pre-requisite for hatching.
Results
A Questionnaire was sent to 252 sheep farmers in NI in March 2012 (covering the years 2009â2012) and replies were received from 228 farmers. Under-dosing, inaccurate calibration of equipment and inappropriate product choice were poor practices identified. Following this survey, the efficacy of treatment of Nematodirus spp. in sheep flocks was evaluated in April and May 2012. Sampling kits were sent to 51 flock owners, all of whom returned pre- and post-anthelmintic dosing faecal samples to the laboratory for analysis. At the time of treatment, 41 flocks were positive for Nematodirus (as diagnosed by the presence of eggs). Reduced benzimidazole efficacy was detected in 35.7% of flocks tested (n = 28). Although only involving a small number of flocks, reduced efficacy of levamisole treatment was detected in 50%, of avermectins in 33% and of moxidectin in 75% of flocks tested (n = 2, 6 and 4, respectively). In the egg hatch experiment, carried out under âchilledâ and ânon-chilledâ conditions, 43% of the eggs in the ânon-chilledâ group were able to hatch, compared to 100% in the âchilledâ group.
Conclusions
The identification of inefficient control strategies argues for continued education of stockholders, in order to improve their management programmes. This is particularly important where the practices might impact on the development of anthelmintic resistance, which has been shown to exist on NI farms. The appropriate choice of anthelmintic is a vital part of this plan. The ability of eggs to hatch under non-chilled conditions demonstrates a flexibility in hatching behaviour. This may represent an adaptation to climate change and account for the recent emergence of a second, autumnal peak of infection
Risk-based learning games improve long-term retention of information among school pupils
Risk heightens motivation and, if used appropriately, may have the potential to improve engagement in the classroom. We have developed a risk-based learning game for school pupils in order to test whether such learning games can improve later recall of information. The study was performed during a series of public engagement workshops delivered by undergraduate students. Undergraduate neuroscience students delivered 90-minute science workshops to 9â10 year old school pupils (n = 448) that were divided into âRiskâ, âNo riskâ and âControlâ classes. âRiskâ classes received periodic multiple-choice questions (MCQs) during the workshops which required small teams of pupils to assign tokens to the answer(s) they believed to be correct. Tokens assigned to the correct answer were returned to the group and an equal number given back as a prize; tokens assigned to incorrect answers were lost. Participation was incentivised by the promise of a brain-related prize to the team with the most tokens at the end of the workshop. âNo riskâ classes received MCQs without the risk component whilst the âControlâ classes received no MCQs. When presented with a neuroscience quiz based on workshop content at the end of the workshop, pupils in the âRiskâ classes exhibited significantly greater recall of information one week later. Quiz scores were higher than scores from the day of the workshop which suggested pupils may have discussed the workshop content outside of the classroom, thereby increasing knowledge over and above what was learned during the workshop. This is supported by feedback from pupils in âRiskâ classes which indicated that âRiskâ workshops were more interesting than âNo riskâ and âControlâ workshops. These data suggest that there is a role for risk in the classroom but further -investigations are required to elucidate the causal mechanisms of improved retention of information
Considering racial and ethnic preferences in communication and interactions among the patient, family member, and physician following diagnosis of localized prostate cancer: study of a US population
Prostate cancer is the most commonly diagnosed cancer among American men. The multiple treatment options for localized prostate cancer and potential side effects can complicate the decision-making process. We describe the level of engagement and communication among the patient, family member, and physician (the decision-making âtriadâ) in the decision process prior to treatment. Using the Family and Cancer Therapy Selection (FACTS) study baseline survey data, we note racial/ethnic variations in communication among the triad. Sensitivity to and awareness of decision-making styles of both the patient and their family member (or caregiver) may enable clinicians to positively influence communication exchanges about important clinical decisions
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