Radiocarbon Content of PM2.5 Ambient Aerosol in Tampa,FL

Radiocarbon ( ¹⁴ C) measurements showed substantial levels of biogenic carbon, 52 to 89%, in PM2.5 samples collected near Tampa, Florida, during May 3–22, 2002. Nighttime biogenic percentages tended to be higher than daytime percentages. The average PM2.5 biogenic carbon concentration was 2.4 μ g m ^{? 3} . The ¹⁴ C (and carbon mass concentration) results were highly reproducible, based on duplicate analyses of samples from collocated samplers. The work includes a first-time treatment of the potential for distortion of the ¹⁴C results by organic artifact during sampling, and a re-consideration of the impact on present-day ¹⁴ C results of the mid-twentieth century “bomb” effect. Neither was found to have a significant impact on the ¹⁴ C results. Concurrent organic and elemental carbon measurements were used to provide estimates of secondary organic aerosol (SOA) in the samples. The results of this study closely resemble those found in other summertime studies near Nashville, Tennesse (1999) and near Houston, Texas (2000) with regard to the joint importance and connection of biogenic PM2.5 and SOA in the Southeastern U.S. during summertime.     

Suppression of continuity-benevolence assumptions (CBS) voices: A theoretical note on the psychology ad psychotherapy of depression: comment.

Interprets the previously reported case of a 27-yr old woman named Lisa by L. Honos-Webb et al (see record 1998-12176-003). Lisa received process-experiential therapy for depression and her case was interpreted in light of the voiced formulation of the assimilation model. Voices that represent continuity and benevolence assumptions (e.g., the world is good; life is worthwhile; I am a valuable person) are called continuity-benevolence assumptions (CBA) voices. When Lisa's CBA voices encountered experiences of mistreatment by her husband and parents, she became angry, but her anger was opposed by her rigid conviction that "we're all supposed to forgive." The current author proposes that Lisa's (CBA) were suppressed, which reduced the anger but left her depressed (feeling like the world is not good; life is not worthwhile; I am not valuable). In therapy, a new meaning bridge was built between Lisa's values and her CBA voices (forgiveness is important, but anger is sometimes appropriate), allowing her to experience the anger without becoming depressed. Similar patterns may occur in other cases of depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic characterization and heterologous expression of brochocin-C, an antibotulinal, two-peptide bacteriocin produced by Brochothrix campestris ATCC 43754

Brochocin-C, produced by Brochothrix campestris ATCC 43754, is active against many strains of the closely related meat spoilage organism Brochothrix thermosphacta and a wide range of other gram-positive bacteria, including spores of Clostridium botulinum. Purification of the active compound and genetic characterization of brochocin-C revealed that it is a chromosomally encoded, two-peptide nonlantibiotic bacteriocin. Both peptides of brochocin-C are ribosomally synthesized as prepeptides that are typical of class II bacteriocins. They are cleaved following Gly-Gly cleavage sites to yield the mature peptides, BrcA and BrcB, containing 59 and 43 amino acids, respectively. Fusion of the nucleotides encoding the signal peptide of the bacteriocin divergicin A in front of the structural genes for either BrcA or BrcB allowed independent expression of each component by the general protein secretion pathway. This revealed the two-component nature of brochocin-C and the necessity for both peptides for activity. A 53-amino-acid peptide encoded downstream of brcB functions as the immunity protein (BrcI) for brochocin-C. In addition, the cloned chromosomal fragment revealed open reading frames downstream of brcI, designated brcT and brcD, that encode proteins with homology to ATP-binding cassette translocator and accessory proteins, respectively, involved in the secretion of Gly-Gly-type bacteriocins.     

Three-dimensional structure of leucocin A in trifluoroethanol and dodecylphosphocholine micelles: spatial location of residues critical for biological activity in type IIa bacteriocins from lactic acid bacteria

The first three-dimensional structure of a type IIa bacteriocin from lactic acid bacteria is reported. Complete 1H resonance assignments of leucocin A, a 37 amino acid antimicrobial peptide isolated from the lactic acid bacterium Leuconostoc gelidum UAL187, were determined in 90% trifluoroethanol (TFE)-water and in aqueous dodecylphosphocholine (DPC) micelles (1:40 ratio of leucocin A:DPC) using two-dimensional NMR techniques (e.g., DQF-COSY, TOCSY, NOESY). Circular dichroism spectra, NMR chemical shift indices, amide hydrogen exchange rates, and long-range nuclear Overhauser effects indicate that leucocin A adopts a reasonably well defined structure in both TFE and DPC micelle environments but exists as a random coil in water or aqueous DMSO. Distance geometry and simulated annealing calculations were employed to generate structures for leucocin A in both lipophilic media. While some differences were noted between the structures calculated for the two different solvent systems, in both, the region encompassing residues 17-31 assumes an essentially identical amphiphilic alpha-helix conformation. A three-strand antiparallel beta-sheet domain (residues 2-16), anchored by the disulfide bridge, is also observed in both media. In TFE, these two regions have a more defined relationship relative to each other, while, in DPC micelles, the C-terminus is folded back onto the alpha-helix. The implications of these structural features with regard to the antimicrobial mechanism of action and target recognition are discussed.     

Aptitude–treatment interactions based on clients' assimilation of their presenting problems.

Assigning clients to treatments on the basis of their differential aptitudes for those treatments may reduce variability and improve the mean outcomes of psychotherapy. The assimilation model suggests that in time-limited treatments, clients with well-assimilated problems would do better in cognitive or behavioral therapies than in psychodynamic, experiential, or interpersonal therapies, whereas the reverse should be the case for clients with poorly assimilated problems. Results for high-, moderate-, and low-assimilation subgroups (based on rating the level of assimilation of problems presented in the first 20 min of first sessions) of clients (N?=?112) randomly assigned to time-limited cognitive-behavioral or psychodynamic-interpersonal treatment supported the first suggestion but not the second (clients with poorly assimilated problems did equally well in both treatments). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Increased incidence of sepsis at birth in neutropenic infants of mothers with preeclampsia

Neutropenia is often found at birth in infants born to mothers with preeclampsia, and is most likely present in utero. To determine whether this neutropenia is associated with an increased incidence of early-onset sepsis, we reviewed the hospital records of 301 low birth weight infants of mothers with preeclampsia. Early-onset sepsis was proved if the result of a culture of blood or cerebrospinal fluid in the first 48 hours of life was positive, or presumed if culture results were negative but two or more clinical signs of sepsis were present and the attending neonatologist believed that an infant was infected and needed at least 7 days of antibiotic therapy. Forty-eight percent of low birth weight infants of mothers with preeclampsia had neutropenia at less than 12 hours of age. Infants with neutropenia had mothers with more severe preeclampsia, were more premature (30 weeks vs 32 weeks), weighed less (1097 gm vs 1615 gm), and were more likely to be small for gestational age. Although maternal and obstetric risk factors for infection were less common in the group with neutropenia, rates of proven or presumed early-onset sepsis were higher (14% vs 2%; p < 0.001). Sepsis was proved in 6% of infants with neutropenia and in none of the infants without neutropenia (p = 0.03). A logistic regression analysis of the relative effects of birth weight, gestational age, and absolute neutrophil count on the incidence of sepsis revealed that only a low absolute neutrophil count correlated significantly with an increased risk of early-onset sepsis in infants with neutropenia.     

Joseph E Whitley, MD, Award. Computer-assisted instruction with interactive videodisc versus textbook for teaching radiology

RATIONALE AND OBJECTIVES: We compared computer-assisted instruction with interactive videodisc (CAI-videodisc) with a textbook to study differences in educational efficacy, time spent, and subjective preferences. METHODS: Two modules of CAI-videodisc, one concerning the radiology of arthritis and the other skeletal trauma, were prepared specifically for advanced medical students and junior house staff. Because the modules were derived from an actual textbook, we were able to conduct a controlled comparison. Our participants were 103 third- and fourth-year medical students taking a required 2-week clerkship in diagnostic radiology. They were assigned as part of their coursework the CAI-video-disc version of one module and the textbook version of the other. Pre- and posttests were administered. RESULTS: The mean scores improved from pre- to posttest after students used both modules in either version (P < 0.001). The gain in score was greater for students using CAI-videodisc; this difference was small only for the arthritis module (P < 0.092), but it was large for the trauma module, even when adjusted for differences in time spent learning (P < 0.001). Significantly more time was spent on the CAI-videodisc versions than the textbook versions (P < 0.004). Subjectively, 43% of the students preferred the CAI-videodisc, 45% preferred the textbook, and 11% had no preference. CONCLUSION: Medical students learned more radiology using a CAI-videodisc program than reading a textbook, but spent more time doing so. Their subjective preferences were equally split.     

Anechoic sphere phantoms for estimating 3-D resolution of very-high-frequency ultrasound scanners

Two phantoms have been constructed for assessing performance of high-frequency ultrasound imagers. They also allow for periodic quality assurance tests and training technicians in the use of higher-frequency scanners. The phantoms contain eight blocks of tissue-mimicking material; each block contains a spatially random distribution of suitably small anechoic spheres having a small distribution of diameters. The eight mean sphere diameters are distributed from 0.10 to 1.09 mm. The two phantoms differ primarily in terms of the frequency dependence of the backscatter coefficient of the background material. Because spheres have no preferred orientation, all three (spatial) dimensions of resolution contribute to sphere detection on an equal basis; thus, the resolution is termed 3-D. Two high-frequency scanners are compared. One employs single-element (fixed focus) transducers (25 and 55 MHz), and the other employs variable focus linear arrays (20, 30, and 40 MHz). The depth range for detection of spheres of each size is determined corresponding to determination of 3-D resolution as a function of depth. As expected, the single-element transducers are severely limited in useful imaging depth ranges compared with the linear arrays. In this preliminary report, only one human observer analyzed images.     

A group-theoretic analysis of symmetric target scattering with application to landmine detection

Landmines are generally constructed such that they possess a high level of geometric symmetry and are then buried in a manner that preserves this symmetry. The scattered response of such a symmetric target will likewise exhibit the symmetry of the target, as well as the electromagnetic reciprocity exhibited by all scatterers. Group theory provides a mathematic tool for describing geometric symmetry, and it can likewise be used to describe the symmetries inherent in the bistatic scattering from mines. Specifically, group theory can be used to determine specific forms of the dyadic Green's function of symmetric scatterers, such that multiple scattering solutions can be determined from a knowledge of a single bistatic geometry. Likewise, group theory can be used both to determine and analyze degenerate cases, wherein specific bistatic responses can be identified as zero regardless of target size, shape, or material. These results suggest a method for classifying subsurface targets as either symmetric or asymmetric. From the group-theoretic analysis, scattering features can be constructed that are indicative of target symmetry, but invariant with respect to other target parameters such as size, shape, or material. These features provide a physically based, target-independent value to aid in mine detection and/or clutter rejection. To test the efficacy of this idea, an extensive collection of bistatic ground-penetrating radar (GPR) measurements was taken for both a symmetric and an asymmetric target. The two targets were easily discernable using symmetry features only, a result that suggests symmetry features can be effective in identifying subsurface targets.