Investigations into Increased Incidence of Severe Gizzard Erosions and Ulcerations in U.S. Commercial Broilers.

During a series of pathology surveys in four production complexes of a U.S. broiler integrator, the technical services veterinarians of an animal health company noted a high incidence of severe gizzard erosions and ulcerations (GEU), prompting further clinical investigation and a battery trial. No growth-promoting antibiotics or ionophore coccidiostats were used during the period of these surveys. All used tribasic copper chloride (TBCC) at ≤120 ppm added copper in broiler rations. Clostridium perfringens was isolated from 83% and 67% of gizzard lesions cultured in two complexes, and cecal C. perfringens most probable number determinations were higher in severely affected than in mildly affected or unaffected birds. Histopathology revealed both acellular koilin fusion defects characteristic of copper toxicity, as well as inflammatory cell infiltrates. Intralesional bacilli suggestive of C. perfringens were noted in 78% of affected flocks examined. Species E Aviadenovirus was isolated from one bird in one complex, and that bird had a single intranuclear inclusion body; no other flocks had Adenoviruses isolated or detected on PCR, nor any inclusion bodies. Other viruses detected were thought to be incidental. A pilot study using feed with supplemental copper from TBCC or copper sulfate and challenge with one of the isolated C. perfringens strains reproduced the lesions. A battery study was conducted with an unchallenged negative control group fed a diet with 16 ppm added copper, a group fed the control diet and orally challenged with 108 organisms of a field strain of C. perfringens at 21 and 22 days, and a group treated with the same diet containing 250 ppm added copper from TBCC and orally challenged with C. perfringens. Birds were necropsied at 23 and 28 days. All challenged groups developed lesions, with those receiving both TBCC and C. perfringens having significantly higher gross and histopathological lesion scores than the unchallenged negative controls. Lesions were qualitatively similar to those in the field and contained suspected C. perfringens bacilli. Because the levels of TBCC used in the commercial birds and in the battery trial generally have been considered safe, and because C. perfringens is usually regarded as a pathogen of the lower GI tract, the possible association of these two agents with GEU is a novel observation and warrants further investigation.

Investigaciones sobre el aumento de la incidencia de erosiones y ulceraciones severas en la molleja en pollos de engorde comerciales en los Estados Unidos. Durante una serie de estudios de patología en cuatro complejos de producción de un integrador de pollos de engorde de los Estados Unidos, veterinarios de servicio técnico de una empresa de salud animal observaron una alta incidencia de erosiones y ulceraciones severas de la molleja (GEU), lo que motivó una mayor investigación clínica y un estudio en batería. Durante el período de estas encuestas no se utilizaron antibióticos promotores del crecimiento ni coccidiostáticos ionóforos. Todos utilizaron cloruro de cobre tribásico (TBCC) con un nivel de ≤120 ppm de cobre agregado en raciones para pollos de engorde. Se aisló Clostridium perfringens del 83% y el 67% de las lesiones de molleja cultivadas en dos complejos, y las determinaciones del número más probable de C. perfringens en los sacos ciegos fueron mayores en aves severamente afectadas que en aves levemente afectadas o no afectadas. La histopatología reveló defectos de fusión de la capa córnea acelular característicos de la toxicidad por cobre, así como infiltrados de células inflamatorias. Se observaron bacilos intralesionales sugestivos de C. perfringens en el 78% de las parvadas afectadas examinadas. La especie Aviadenovirus E se aisló de un ave en un complejo, y esa ave tenía un único cuerpo de inclusión intranuclear; en ninguna otra parvada se aislaron o detectaron adenovirus mediante PCR, ni se observaron cuerpos de inclusión. Se pensó que otros virus detectados fueron incidentales. Un estudio piloto que utilizó alimento con cobre suplementario de cloruro de cobre tribásico o sulfato de cobre y con desafío con una de las cepas aisladas de C. perfringens reprodujo las lesiones. Se realizó un estudio de batería con un grupo de control negativo no desafiado alimentado con una dieta con 16 ppm de cobre agregado, un grupo alimentado con la dieta de control y desafiado por vía oral con 108 organismos de una cepa de campo de C. perfringens a los 21 y 22 días, y un grupo tratado con la misma dieta que contenía 250 ppm de cobre agregado de cloruro de cobre tribásico y desafiados por vía oral con C. perfringens. A las aves se les realizó la necropsia a los 23 y 28 días. Todos los grupos desafiados desarrollaron lesiones, y aquellos que recibieron cloruro de cobre tribásico y C. perfringens tuvieron puntuaciones de lesiones macroscópicas e histopatológicas significativamente más altas que los controles negativos no desafiados. Las lesiones eran cualitativamente similares a las del campo y contenían bacilos sospechosos de C. perfringens. Debido a que los niveles de cloruro de cobre tribásico utilizados en las aves comerciales y en el ensayo en batería generalmente se han considerado seguros, y debido a que C. perfringens generalmente se considera un patógeno del tracto gastrointestinal inferior, la posible asociación de estos dos agentes con erosiones y ulceraciones severas de la molleja es una observación reciente y justifica una mayor investigación.

Clinical laboratory characteristics in patients with suspected COVID-19: One single-institution experience.

OBJECTIVES: Since December 2019, the outbreak of coronavirus disease 2019 (COVID-19) has become a worldwide pandemic. The aim of the study is to investigate the demographic, clinical, and laboratory characteristics in suspected COVID-19 patients in our institution. METHODS: In this retrospective study, we investigated suspected COVID-19 patients admitted to the University of Alabama at Birmingham with a request for an interleukin-6 send-out test, from March 28 to June 27, 2020. Patients' demographic, clinical, and laboratory characteristics were collected by chart review. RESULTS: Fifty patients suspected with COVID-19 were included in our study, of whom 24 patients were positive with severe acute respiratory syndrome coronavirus-2 infection and 26 were negative. During the observation period, 30 patients were discharged, 17 died during hospitalization, and three remained in hospital. Compared to non-COVID-19 patients, COVID-19 patients had older age, more comorbidities, and elevated levels of inflammation markers such as erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), serum ferritin, and lactate dehydrogenase (LDH). However, there was no significant difference in laboratory data between survivors and nonsurvivors in COVID-19 patients in our study. CONCLUSION: This study indicated that potential risk factors of older age, multiple comorbidities, and high levels of ESR, CRP, serum ferritin, and LDH could help the clinician to identify potential COVID-19 patients. However, this data needs to be further validated in a larger population.

Efficacy of Trace Mineral-Amino Acid Complexes in a Necrotic Enteritis Challenge Model.

Necrotic enteritis (NE) is a common and costly disease of poultry caused by virulent toxigenic strains of Clostridium perfringens. Although the importance of trace minerals for intestinal integrity and health is well documented, there is little information on their role in ameliorating the effects of NE. The two studies reported here examined the effects of replacing a portion of the dietary zinc (Zn), copper (Cu), and manganese (Mn) supplied as sulfates in the control diets with metal-amino acid-complexed minerals in a NE-challenge model consisting of coccidiosis and Clostridium perfringens. In a 28-day battery study, the treatments were the following: (1) no additional Zn or Mn, unchallenged (negative control); (2) no added Zn or Mn, challenged (positive control); (3) added ZnSO4 and MnSO4 at 100 ppm each, challenged; (4) additional ZnSO4 at 60 ppm, Availa-Zn at 40 ppm (Low), and MnSO4 at 100 ppm, challenged; (5) added ZnSO4 at 60 ppm, Availa-Zn at 60 ppm (high), and MnSO4 at 100 ppm, challenged; and (6) added ZnSO4 at 60 ppm, Availa-Zn at 40 ppm, MnSO4 at 60 ppm, and Availa-Mn at 40 ppm, challenged. None of the treatments ameliorated gross lesion scores, but all reduced NE-associated mortality compared with the positive control. At 28 days, the group supplemented with Availa-Zn at 40 ppm (low) had a lower body weight than challenged groups supplemented with Zn and the negative control. In a floor pen study, the five treatment groups were the following: (1) Zn, Mn, and Cu from sulfate sources at 100, 100, and 20 ppm respectively; (2) Zn, Mn, and Cu from sulfate sources at 40, 100, and 20 ppm, respectively, plus Zn from Availa-Zn at 60 ppm; (3) Zn and Mn from sulfate sources at 40 and 100 ppm, respectively, plus Zn from Availa-Zn at 60 ppm and Cu from Availa-Cu at 10 ppm; (4) Zn, Mn, and Cu from sulfate sources at 60, 60, and 20 ppm, respectively, plus Zn and Mn from Availa-Zn/Mn at 40 and 40 ppm, respectively; and (5) bacitracin methylene disalicylate at 55 g/metric ton with Zn, Mn, and Cu from sulfate sources at 100, 100, and 20 ppm, respectively (Zoetis, Inc., Kalamazoo, MI). None of the treatments reduced lesion scores. The Availa-Zn and Availa-Zn/Mn had lower mortality than the sulfate-supplemented feed, whereas Availa-Zn/Cu and bacitracin methylene disalicylate were intermediate and did not differ from the other groups. Considering both trials together, and by using NE mortality as the discriminating factor, we found that adding Zn and Mn exceeding National Research Council requirements reduced NE-associated mortality, and in the floor pen study, complexed Zn and complexed Zn plus Mn appeared to be superior to sulfates.

Efficacy of Butyric and Valeric Acid Esters in a Necrotic Enteritis Challenge Model.

Restrictions on the use of antibiotics in poultry production have increased interest in nonantibiotic alternatives to control necrotic enteritis (NE). Volatile fatty acids, and in particular butyric acid preparations, have shown potential as aids in controlling NE. Valeric acid compounds may be a new additional alternative. This series of three trials compared the effects of tributyrin, monovalerin, which is an organic acid mixture, and bacitracin in a NE challenge model consisting of challenge with coccidiosis followed by Clostridium perfringens. Trial 1 was a pen trial comparing tributyrin at 0.5 kg/metric ton continuously in the feed, a proprietary organic acid blend at 1 kg per 1000 L as a metaphylactic treatment in the water, and bacitracin in the feed at 55 g/metric ton. Tributyrin and the organic acid mixture were at least as effective as bacitracin in controlling the growth- and efficiency-suppressing effects of the NE challenge, and the organic acid mixture reduced NE lesion scores. None of the treatments reduced mortality. Trial 2 was a battery study comparing monovalerin at 1.5 kg/metric ton and bacitracin in the feed. Both interventions provided significant control of both clinical and subclinical NE, with bacitracin being slightly superior to monovalerin. Trial 3 was a pen trial comparing monovalerin at 1 kg or 1.5 kg/metric ton continuously, or 0.5 kg/metric ton from 0 to 14 days and 0.25 kg/metric ton from 14 to 42 days (variable dose), to tributyrin at the same variable-dose schedule. The higher dose of monovalerin appeared to suppress feed intake and weight gain prechallenge but also produced the lowest NE mortality and the lowest total mortality of the challenged groups. All of the treatments except the variable-dose monovalerin treatment demonstrated reductions in NE lesion scores compared with the positive challenge control group; however, they did not control mortality and had fewer effects on the performance effects of subclinical NE. Results of these studies indicate that the organic acid products monovalerin and tributyrin may be useful adjuncts to reduce NE in antibiotic-free broiler production.

An optimist's view on limiting necrotic enteritis and maintaining broiler gut health and performance in today's marketing, food safety, and regulatory climate.

The future poultry nutritionist, veterinarian, and husbandryman will have many new regulatory requirements and consumer preferences to navigate in addition to their normal responsibility of raising birds in a cost-efficient and wholesome manner. New challenges include changes to antibiotic use, increased food safety regulations, and more concern over how birds are raised and how to dispose of poultry house waste. All of these new programs and new regulations will alter how we have been raising birds for the last 60 years since the inception of the integrated poultry industry. The most significant change may be the voluntary or regulatory withdrawal of the use of antibiotics in poultry production. In North America, this withdrawal of antibiotic use includes removal of in-ovo antibiotics, performance-improving antibiotics or antibiotic growth promotors (AGP), and the polyether ionophore antibiotics (ionophore anticoccidials).The removal of antibiotics in poultry production may result in welfare concerns due to elevated mortality and less efficient feed conversion, resulting in greater environmental impacts from increased manure production and more use of grain per unit of meat produced. There also may be concerns with greater intestinal disease in the birds resulting in increased numbers of foodborne illness-causing bacteria such as Salmonella sp. or Campylobacter sp. on the carcass. A major impact will be the disease necrotic enteritis (NE). This review will focus on the pathophysiology of NE, the management of the disease, and the additional effects on growth rate, feed efficiency, and body weight that may be associated with NE.

Investigation of a field-widened Mach-Zehnder receiver to extend Fe Doppler lidar wind measurements from the thermosphere to the ground.

A receiver employing a field-widened Mach-Zehnder interferometer (MZI) is investigated for extending the wind measurement range of a narrow-band Fe Doppler lidar operating at 372 nm from its existing measurement range in the mesosphere and lower thermosphere (MLT) down to near the ground. This design uses the multiple transmitted frequencies available from the base Fe Doppler lidar in combination with a novel MZI receiver to make a measurement of the Doppler shift that rejects the influence of atmospheric parameters such as the aerosol backscatter ratio, temperature, and pressure of the lidar volume and receiver parameters such as the geometric overlap, the chopper function, and any other factor affecting the proportion of the signal in both channels of the MZI equally. A ratio is constructed from the three frequencies and two channels of the interferometer that exhibits a measurement performance of 1.75 times the Cramer-Rao lower bound, which is comparable to the dual MZI (DMZ) while preserving the insensitivity to backscatter spectrum of the quad MZI (QMZ). In addition, we show how the use of multiple transmitted frequencies can yield a wind measurement wherein the accuracy is insensitive to the optical imperfection and misalignment of the MZI or any other factor that affects the contrast, though the precision is still impacted by the fringe contrast. Simply adding a second surface mirror of a particular thickness to the basic tilted MZI can allow the field of the MZI to be widened sufficiently for most resonance Doppler lidar receivers in operation today. Provided that the detection sensitivity in each channel is known, the original resonance fluorescence and Rayleigh scattering signals can be recovered by simply scaling and adding the contributions from both channels. Consequently, the wind and temperature from the MLT region and the temperature from the Rayleigh region can be derived alongside the Rayleigh Doppler wind measurement without compromising the measurement precision. Using actual data obtained recently from a Major Research Instrumentation Fe Doppler lidar, we show the expected measurement performance and some potential scientific avenues for this embodiment of a "whole-atmosphere" lidar system.

Off-resonance effects in (14)N NQR signals from the pulsed spin-locking (PSL) and three-pulse echo sequence; a study for monoclinic TNT.

In NQR detection applications signal averaging by the summation of rapidly regenerated signals from multiple pulse sequences of the pulsed spin-locking (PSL) type is often used to improve sensitivity. It is important to characterise and if possible minimise PSL sequence off-resonance effects since they can make it difficult to optimise detection performance. We illustrate this with measurements of the variation of the decay time T2e and the amplitude of PSL signal trains with pulse spacing and excitation offset frequency for the 870 kHz ν+(14)N NQR line of monoclinic TNT under carefully stabilised temperature conditions. We have also carried out a similar study of signals from monoclinic TNT and 1H-1,2,3-triazole generated by a three-pulse echo sequence and the results are shown to agree well with a theoretical treatment appropriate to polycrystalline NQR samples such as TNT for which spin I=1, asymmetry parameter η≠0 and T1≫T2. Based on this theory we derive simple models for calculating TNT PSL signal trains and hence the pulse spacing and off-resonance dependence of signal amplitude and T2e which we compare to our experimental data. We discuss the influence of PSL echo summation on off-resonance effects in detected signal intensity and show how a phase-alternated multiple pulse sequence can be used in combination with the PSL sequence to eliminate variation in detection performance due to off-resonance effects.

(14)N NQR, relaxation and molecular dynamics of the explosive TNT.

Multiple pulse sequences are widely used for signal enhancement in NQR detection applications. Since the various (14)N NQR relaxation times, signal decay times and frequency of each NQR line have a major influence on detection sequence performance, it is important to characterise these parameters and their temperature variation, as fully as possible. In this paper we discuss such measurements for a number of the ν+ and ν- NQR lines of monoclinic and orthorhombic TNT and relate the temperature variation results to molecular dynamics. The temperature variation of the (14)N spin-lattice relaxation times T1 is interpreted as due to hindered rotation of the NO2 group about the C-NO2 bond with an activation energy of 89 kJ mol(-1) for the ortho and para groups of monoclinic TNT and 70 kJ mol(-1) for the para group of orthorhombic TNT.

High-efficiency receiver architecture for resonance-fluorescence and Doppler lidars.

A high-efficiency lidar receiver architecture that emphasizes boosting the receiver collection efficiency of resonance-fluorescence and Doppler lidars has opened up new avenues of study for the mesosphere and lower thermosphere-extended (MLT-X) at sites in Boulder, Colorado, USA, and Cerro Pachón, Chile. Described in this work are in-depth considerations in the design, construction, and alignment of Na Doppler lidar receivers that have yielded signal levels typically 5-10 times higher per power-aperture product than any demonstrated in the literature, to these authors' knowledge, making studies of fine-scale MLT turbulence and tenuous thermospheric layers in Na possible with temperature and vertical wind capability for the first time. A lowering of the detection threshold by higher receiver collection efficiency at Cerro Pachón has enabled this Na Doppler lidar to extend its measurement range far higher into the thermosphere, to regions with Na density less than 3 cm(-3). With renewed interest in the MLT-X region prompted by recent lidar discoveries of Fe in the thermosphere reaching 170 km at McMurdo, Antarctica, the receiver optimizations we have made now enable addressing an important need in the community. In addition, the higher spatial and temporal resolutions afforded by high signal-to-noise ratio, down to resolutions of ∼20 s and ∼20 m, promise to make the first direct measurements of eddy flux in the mesopause region possible. Results from deployment of optimized receivers at the Table Mountain Lidar Observatory in Boulder, the Andes Lidar Observatory at Cerro Pachón, and the Arecibo Observatory in Puerto Rico are presented to demonstrate the power and portability of our methods that are readily applicable to other lidar varieties, including, but not limited to, the newly developed Fe Doppler lidar and recently upgraded K Doppler lidar.

Mucosal lesions and mortality associated with the use of a ferric sulfate poultry litter amendment product.

Within hours of chick delivery, acute mortality and mucosal lesions were reported on 2 northeast Georgia broiler farms that had applied a ferric sulfate litter amendment product. Histological evaluation of the larynx, tongue, and surrounding stroma revealed multifocal areas of necrosis or degeneration of the oral mucosa, acute focal necrotizing cellulitis, and the presence of a brown-black pigmented material adhered to affected epithelial and mucosal surfaces. Multifocal to diffuse ventricular koilin degeneration and acute hemorrhage was also demonstrated in association with pigmented adherent material on affected surfaces. Perls iron stain revealed that adherent material on affected tissues was strongly positive for iron. An experiment was designed to reproduce clinical signs, lesions, and mortality using the same litter amendment product. The ferric sulfate litter amendment was confirmed as the causative agent.

Nitrogen-14 nuclear quadrupole resonance spectroscopy: a promising analytical methodology for medicines authentication and counterfeit antimalarial analysis.

We report the detection and analysis of a suspected counterfeit sample of the antimalarial medicine Metakelfin through developing nitrogen-14 nuclear quadrupole resonance ((14)N NQR) spectroscopy at a quantitative level. The sensitivity of quadrupolar parameters to the solid-state chemical environment of the molecule enables development of a technique capable of discrimination between the same pharmaceutical preparations made by different manufacturers. The (14)N NQR signal returned by a tablet (or tablets) from a Metakelfin batch suspected to be counterfeit was compared with that acquired from a tablet(s) from a known-to-be-genuine batch from the same named manufacturer. Metakelfin contains two active pharmaceutical ingredients, sulfalene and pyrimethamine, and NQR analysis revealed spectral differences for the sulfalene component indicative of differences in the processing history of the two batches. Furthermore, the NQR analysis provided quantitative information that the suspected counterfeit tablets contained only 43 ± 3%, as much sulfalene as the genuine Metakelfin tablets. Conversely, conventional nondestructive analysis by Fourier transform (FT)-Raman and FT-near infrared (NIR) spectroscopies only achieved differentiation between batches but no ascription. High performance liquid chromatography (HPLC)-UV analysis of the suspect tablets revealed a sulfalene content of 42 ± 2% of the labeled claim. The degree of agreement shows the promise of NQR as a means of the nondestructive identification and content-indicating first-stage analysis of counterfeit pharmaceuticals.

Variable-pitch rectangular cross-section radiofrequency coils for the nitrogen-14 nuclear quadrupole resonance investigation of sealed medicines packets.

The performance of rectangular radio frequency (RF) coils capable of being used to detect nuclear quadrupole resonance (NQR) signals from blister packs of medicines has been compared. The performance of a fixed-pitch RF coil was compared with that from two variable-pitch coils, one based on a design in the literature and the other optimized to obtain the most homogeneous RF field over the whole volume of the coil. It has been shown from (14)N NQR measurements with two medicines, the antibiotic ampicillin (as trihydrate) and the analgesic medicine Paracetamol, that the latter design gives NQR signal intensities almost independent of the distribution of the capsules or pills within the RF coil and is therefore more suitable for quantitative analysis.

Engaging basic scientists in translational research: identifying opportunities, overcoming obstacles.

This report is based on the Federation of American Societies for Experimental Biology's symposium, "Engaging basic Scientists in Translational Research: Identifying Opportunities, Overcoming Obstacles," held in Chevy Chase, MD, March 24-25, 2011. Meeting participants examined the benefits of engaging basic scientists in translational research, the challenges to their participation in translational research, and the roles that research institutions, funding organizations, professional societies, and scientific publishers can play to address these challenges.

14N quadrupole resonance and 1H T1 dispersion in the explosive RDX.

The explosive hexahydro-1,3,5-trinitro-s-triazine (CH2-N-NO2)3, commonly known as RDX, has been studied by 14N NQR and 1H NMR. NQR frequencies and relaxation times for the three ν+ and ν- lines of the ring 14N nuclei have been measured over the temperature range 230-330 K. The 1H NMR T1 dispersion has been measured for magnetic fields corresponding to the 1H NMR frequency range of 0-5.4 M Hz. The results have been interpreted as due to hindered rotation of the NO2 group about the N-NO2 bond with an activation energy close to 92 kJ mol(-1). Three dips in the 1H NMR dispersion near 120, 390 and 510 kHz are assigned to the ν0, ν- and ν+ transitions of the 14NO2 group. The temperature dependence of the inverse line-width parameters T2∗ of the three ν+ and ν- ring nitrogen transitions between 230 and 320 K can be explained by a distribution in the torsional oscillational amplitudes of the NO2 group about the N-NO2 bond at crystal defects whose values are consistent with the latter being mainly edge dislocations or impurities in the samples studied. Above 310 K, the 14N line widths are dominated by the rapid decrease in the spin-spin relaxation time T2 due to hindered rotation of the NO2 group. A consequence of this is that above this temperature, the 1H T1 values at the quadrupole dips are dominated by the spin mixing time between the 1H Zeeman levels and the combined 1H and 14N spin-spin levels.

Pathway modulators and inhibitors.

Inhibitors of specific cellular pathways are useful for investigating the roles of proteins of unknown function, and for selectively inhibiting a protein in complex pathways to uncover its relationships to other proteins in this and other interacting pathways. This appendix provides links to Web sites that describe cellular processes and pathways along with the various classes of inhibitors, numerous references, downloadable diagrams, and technical tips.

Magnetic field-cycling NMR and (14)N, (17)O quadrupole resonance in the explosive pentaerythritol tetranitrate (PETN).

The explosive pentaerythritol tetranitrate (PETN) C(CH(2)-O-NO(2))(4) has been studied by (1)H NMR and (14)N NQR. The (14)N NQR frequency and spin-lattice relaxation time T(1Q) for the nu(+) line have been measured at temperatures from 255 to 325K. The (1)H NMR spin-lattice relaxation time T(1) has been measured at frequencies from 1.8kHz to 40MHz and at temperatures from 250 to 390K. The observed variations are interpreted as due to hindered rotation of the NO(2) group about the bond to the oxygen atom of the CH(2)-O group, which produces a transient change in the dipolar coupling of the CH(2) protons, generating a step in the (1)H T(1) at frequencies between 2 and 100kHz. The same mechanism could also explain the two minima observed in the temperature variation of the (14)N NQR T(1Q) near 284 and 316K, due in this case to the transient change in the (14)N...(1)H dipolar interaction, the first attributed to hindered rotation of the NO(2) group and the second to an increase in torsional amplitude of the NO(2) group due to molecular distortion of the flexible CH(2)-O-NO(2) chain which produces a 15% increase in the oscillational amplitude of the CH(2) group. The correlation times governing the (1)H T(1) values are approximately 25 times longer than those governing the (14)N NQR T(1Q), explained by the slow spin-lattice cross-coupling between the two spin systems. At higher frequencies, the (1)H T(1) dispersion results show well-resolved dips between 200 and 904kHz assigned to level crossing with (14)N and weaker features between 3 and 5MHz tentatively assigned to level crossing with (17)O.

What do medical students understand by research and research skills? Identifying research opportunities within undergraduate projects.

BACKGROUND: Undergraduate research exposure leads to increased recruitment into academic medicine, enhanced employability and improved postgraduate research productivity. Uptake of undergraduate research opportunities is reported to be disappointing, and little is known about how students perceive research. AIM: To investigate opportunities for undergraduate participation in research, recognition of such opportunities, and associated skills development. METHOD: A mixed method approach, incorporating student focus and study groups, and documentary analysis at five UK medical schools. RESULTS: Undergraduates recognised the benefits of acquiring research skills, but identified practical difficulties and disadvantages of participating. Analysis of 905 projects in four main research skill areas - (1) research methods; (2) information gathering; (3) critical analysis and review; (4) data processing - indicated 52% of projects provided opportunities for students to develop one or more skills, only 13% offered development in all areas. In 17%, project descriptions provided insufficient information to determine opportunities. Supplied with information from a representative sample of projects (n = 80), there was little consensus in identifying skills among students or between students and researchers. Consensus improved dramatically following guidance on how to identify skills. CONCLUSIONS: Undergraduates recognise the benefits of research experience but need a realistic understanding of the research process. Opportunities for research skill development may not be obvious. Undergraduates require training to recognise the skills required for research and enhanced transparency in potential project outcomes.

Spectral estimation of irregularly sampled exponentially decaying signals with applications to RF spectroscopy.

The problem of estimating the spectral content of exponentially decaying signals from a set of irregularly sampled data is of considerable interest in several applications, for example in various forms of radio frequency spectroscopy. In this paper, we propose a new nonparametric iterative adaptive approach that provides a solution to this estimation problem. As opposed to commonly used methods in the field, the damping coefficient, or linewidth, is explicitly modeled, which allows for an improved estimation performance. Numerical examples using both simulated data and data from NQR experiments illustrate the benefits of the proposed estimator as compared to currently available nonparametric methods.

Pathway modulators and inhibitors.

Inhibitors of specific cellular pathways are useful for investigating the roles of proteins of unknown function, and for selectively inhibiting a protein in complex pathways to uncover its relationships to other proteins in this and other interacting pathways. This appendix provides links to Web sites that describe cellular processes and pathways along with the various classes of inhibitors, numerous references, downloadable diagrams, and technical tips.