NWChem: Past, present, and future.

Specialized computational chemistry packages have permanently reshaped the landscape of chemical and materials science by providing tools to support and guide experimental efforts and for the prediction of atomistic and electronic properties. In this regard, electronic structure packages have played a special role by using first-principle-driven methodologies to model complex chemical and materials processes. Over the past few decades, the rapid development of computing technologies and the tremendous increase in computational power have offered a unique chance to study complex transformations using sophisticated and predictive many-body techniques that describe correlated behavior of electrons in molecular and condensed phase systems at different levels of theory. In enabling these simulations, novel parallel algorithms have been able to take advantage of computational resources to address the polynomial scaling of electronic structure methods. In this paper, we briefly review the NWChem computational chemistry suite, including its history, design principles, parallel tools, current capabilities, outreach, and outlook.

Effectiveness of parks in protecting tropical biodiversity.

We assessed the impacts of anthropogenic threats on 93 protected areas in 22 tropical countries to test the hypothesis that parks are an effective means to protect tropical biodiversity. We found that the majority of parks are successful at stopping land clearing, and to a lesser degree effective at mitigating logging, hunting, fire, and grazing. Park effectiveness correlates with basic management activities such as enforcement, boundary demarcation, and direct compensation to local communities, suggesting that even modest increases in funding would directly increase the ability of parks to protect tropical biodiversity.

Spectral fitting of NMR spectra using an alternating optimization method with a priori knowledge.

As alternatives to the fast Fourier transform, advanced parametric methods based on the damped sinusoidal data model have been devised to better quantify the nuclear magnetic resonance (NMR) spectroscopy time-domain data. Previously, linear prediction (LP) fitting methods using Householder triangularization and singular value decomposition (SVD) techniques have been applied to the NMR spectroscopy data analysis. In this paper, we propose an alternating optimization method to quantify the time-domain NMR spectroscopy data. The proposed algorithm uses the a priori knowledge of the possible frequency intervals of the damped sinusoids to obtain more accurate parameter estimates when the NMR spectroscopy data are obtained under low signal-to-noise ratio conditions and the peaks are close together. None of the LP and SVD type of methods can use such approximate a priori knowledge. We have shown with measured NMR spectroscopy data that the proposed algorithm can be used to obtain accurate parameter estimates of frequencies, amplitudes, and damping ratios of the damped sinusoids and therefore the ultimate fit of the spectrum by using the a priori knowledge about the possible frequency intervals of the damped sinusoids.

Relative speeds of Kodak computed radiography phosphors and screen-film systems.

Relative mAs values required to generate a constant plate readout signal for the Kodak Ektascan general purpose (GP-25) and high resolution (HR) photostimulable phosphors were measured as a function of x-ray beam quality and for a range of representative x-ray examinations. The signal intensity was determined from the exposure index (EI) generated during the read out of uniformly exposed phosphor imaging plates. These data were compared to the corresponding relative mAs values required to produce a constant film density of Lanex screen-film combinations with nominal speeds of 40, 400, and 600. The relative detection performance of the photostimulable phosphors generally decreased with increasing kVp and beam filtration. The relative response of GP-25 phosphors was independent of examination type, and modified by approximately 10% when scattered radiation was present. The HR phosphor was more efficient than a Lanex Single Fine extremity screen used with an EM-1 film. These relative response data will be useful for selecting the x-ray technique factors which minimize patient dose in x-ray examinations performed with photostimulable phosphors.

Picture memory (pseudomatching) in rhesus monkeys.

Pseudomatching, the selection of the correct comparison stimulus without dependence on presentation of a sample stimulus, was demonstrated in monkeys being trained ostensibly on a matching-to-sample, shock-avoidance tast. Pseudomatiching occurred whenever the problem sets were not fully counterbalanced for key position and correct symbol and seemed to represent memorization of specific stimulus configurations. Some animals showed the capacity to memorize hundreds of different 4-choice problems as indicated by test trials on which the samples were omitted. To prevent pseudomatching contamination of matching-to-sample behavior one must arrange full counterbalancing and randomization of stimuli and reinforcements. Pseudomatiching test trials are also recommended.

SU-E-I-30: Impact of Physician Practice on Patient Radiation Dose during CT Guided Biopsy Procedures.

PURPOSE: The major concern with CT fluoroscopy is patient radiation dose, which is determined by applied technical parameters as well as practitioner/operator practice, e.g. habits and choice of dose saving features. This study is to investigate the effects of these intangible factors on patient doses. METHODS: 381 patients underwent CT biopsy were retrospectively studied. Patient doses (dose length product, DLP) were analyzed and compared. Comparisons were made among physicians using only conventional intermittent shots, physicians using a low mA dose saving feature, and physicians using a combination of both. Linear regression analyses were performed to investigate any possible relationship between the variables and the patient dose. The Patient detriment index (PDI) was developed to set a threshold for the purpose of the Joint Commission sentinel dose events monitoring. An odds ratio was calculated to determine the odds of a group of patients receiving a dose above the median threshold when compared to another group. RESULTS: The median DLP for all physicians was 1194 mGy-cm. There is a significant difference (p<0.01) between the doses patients received (DLP=539.8 ±76 mGy-cm) when physicians used dose saving feature vs. when the feature was not used (DLP=1269.7±659 mGy-cm). In general, those physicians who used dose saving feature have a lower relative PDI (<1) compared to the PDIs (>1) without dose feature. This is not absolute since some physicians who did not use the dose saving feature have PDIs

SU-E-I-33: Advances in Dose Metrics and Dose Reduction Strategies for Interventional Fluoroscopy.

PURPOSE: To explore recent advances in available dose metrics and dose reduction features and their impacts during various fluoroscopy procedures. METHODS: Besides traditional dose metrics (cumulative dose, DAP, etc), recent methods such as real time dose mapping and dose calculation from DICOM information and their relevance to entrance skin exposure (ESE) are demonstrated. Dose reduction features and their potential effects on ESE are explored for different interventional procedures, including dose setting options, frame rate settings, wedges, software options and how these help reduce patient dose, etc. Real time dose monitoring techniques such as DoseAware are investigated. Dose alert such as flagging higher doses at about half of the Joint Commission sentinel event limit, Dose Index Registry and their impacts are discussed. Habit related practices, such as a physician leaning over patients, are highlighted, also taking foot off the fluoroscopy pedal when not needed, and best places to stand are illustrated. A practice improvement procedure involving measurement, analysis and improvement actions is instituted. We also discuss the impact of physician follow up letters to patients who might not have reached the JC Sentinel Event limits but may still have skin issues. RESULTS: In our institutes, these efforts have led to reduction of both patient dose and personnel exposure for interventional procedures. The recording of technical parameters and fluoroscopy dose by the staff has led to a better understanding of appropriate dose levels and technique settings for each procedure. CONCLUSIONS: This article can serve as a refresher for radiological staff on how to protect patients and themselves from high doses, while providing the best care possible. It can also serve as criteria for health care providers to institute changes and make quality improvement in interventional practices.

Inadequate vitamin D status in adolescents with substantial bone mineral density loss during the use of depot medroxyprogesterone acetate injectable contraceptive: a pilot study.

STUDY OBJECTIVE: To examine vitamin D and parathormone (PTH) levels in adolescents who experienced substantial bone mineral density (BMD) loss during depot medroxyprogesterone acetate (DMPA) use. DESIGN: A non-randomized, multi-center study, during which DMPA was administered every 12 weeks and evaluation of lumbar spine and hip BMD by dual-energy X-ray absorptiometry (DXA) was conducted every 6 months. A blood sample for vitamin D and PTH measurements was obtained from adolescents who experienced >5% BMD loss. Vitamin D deficiency was defined as 25-hydroxyvitamin D (25OHD) level of <20 ng/mL, insufficiency as 25OHD level of 20-30 ng/mL, and sufficiency as 25OHD level of >30 ng/mL. RESULTS: Evaluation of vitamin D and PTH was carried out in 15 participants who experienced BMD loss of > or = 5% during DMPA use. At initiation of DMPA, participants had mean (+SE) age 17+1 years, gynecologic age 61+4 months, and body mass index 24+1.5 kg/m2. Racial/ethnic distribution was: Caucasian--7 girls, Hispanic--4 girls, African-American--3 girls, and other--1 girl. Six participants had BMD loss of >5% after 2 DMPA injections, five after 3 injections, one after 5 injections, one after 8 injections, one after 10 injections, and one after 13 injections. Only one girl (7%) had sufficient vitamin D. The other participants had vitamin D insufficiency (50%) or deficiency (43%). Participants' mean (+SE) PTH was 22+4 pg/mL (reference range 7-53 pg/mL), and mean (+SE) 1,25-dihydroxyvitamin D was 56+5 pg/mL (reference range 22-67 pg/mL). CONCLUSIONS: Inadequate vitamin D status was evident among the majority of female adolescents who experienced a substantial BMD loss while using DMPA.

Neurologic evaluation of the upper extremity.

Symptoms and disease processes can overlap, and neurologic symptoms of the hand or arm are not necessarily due to local pathology. To combat these difficulties, the authors present a basic review of neuroanatomy, the neurologic examination, the principles of electromyography, and the process of formulation.

Reflex sympathetic dystrophy: misdiagnosis in patients with dysfunctional postures of the upper extremity.

The purpose of this case-control study was to assess the frequency of the inappropriate diagnosis of reflex sympathetic dystrophy (RSD) in patients who presented with dysfunctional postures of the upper extremity (n = 43). This group of patients with a dysfunctional posture was compared with a randomly selected control group of patients who presented with pain but no dysfunctional posture (n = 88). The patients underwent radiographic evaluation after review of previous medical records and history and physical examination. Patients with dysfunctional postures had a significantly higher frequency (63%) of a previous inappropriate diagnosis of RSD compared with the control group (6%). None of the patients in either group had objective findings consistent with a diagnosis of RSD. Patients presenting with dysfunctional postures of the upper extremity may be misdiagnosed as having RSD and rarely meet the criteria for this diagnosis.

Molecular properties of the oleoyl-phosphatidylcholine desaturase from Arachis hypogaea L.

Deficiencies in the activity of the microsomal oleoyl phosphatidylcholine (oleoyl-PC) desaturase from peanuts are the basis of the high oleate oil. Mutation of aspartate-150 to asparagine and the attendant decrease in activity, together with the loss in expression of the higher activity transcript, was the molecular basis of the high oleate trait. The ability of oleoyl-PC desaturase to desaturate palmitoleate, oleate and 10(Z) nonadecenoate to methylene-interrupted products was not consistent with description of this activity as a Delta(12) or omega-6 desaturase. Electrospray MS was used to examine the intact phospholipid products of desaturation by the oleoyl-PC desaturase. PC and phosphatidylinositol containing unsaturated moieties could be desaturated. The enzyme can act on either sn-1 or sn-2 moieties. Phosphatidylethanolamine was a poor substrate.