bluuebunny/crossref_metadata_2025 huggingface dataset:
“Staying in Focus” — An Online Optics Tutorial on the Eye
Authors: Hoeling Barbara M.
Published: January 2011

The human eye and its vision problems are often used as an entry subject and attention grabber in the teaching of geometrical optics.1 While this is a real-life application students can relate to, it is difficult to visualize how the eye forms images by studying the still pictures and drawings in a textbook. How to draw a principal ray diagram or how to calculate the image distance from a given object distance and focal length might be clear to most students after studying the book, but even then they often lack an understanding of the “big picture.” Where is the image of a very far away object located? How come we can see both far away and close-by objects focused (although not simultaneously)? Computer animations,2 popular with our computer-game savvy students, provide considerably more information than the still images, especially if they allow the user to manipulate parameters and to observe the outcome of a “virtual” experiment. However, as stand-alone learning tools, they often don't provide the students with the necessary physics background or instruction on how to use them.
Whither Does the Sun Rove?
Authors: Gangui Alejandro
Published: January 2011

If one asked some friends where on the horizon they should expect to see the sunrise, half of the answers would be "in the east." Of course, something analogous would happen with the sunset and the west. However, sunrise and sunset virtually never occur at these cardinal points. In fact, those answers correctly describe observations only during the equinoxes, when either autumn or spring begin. Once we recall this, the next natural question to ask ourselves is: how far from the east (or from the west) the rising (or setting) Sun is located for a given latitude of the observer and for a given day of the year. In this paper we supply some simple tools to easily visualize the angular (southward or northward) departure of the rising and setting Sun on the horizon from the east-west direction in a pictorial way, without the need of mathematics. These tools have proven a valuable resource in teaching introductory physics and astronomy courses.
Dramatic (and Simple!) Demonstration of Newton's Third Law
Authors: Feldman Gerald
Published: January 2011

An operational understanding of Newton's third law is often elusive for students. Typical examples of this concept are given for contact forces that are closer to the students' everyday experience. While this is a good thing in general, the reaction force can sometimes be taken for granted, and the students can miss the opportunity to really think about what is going on. In the case of magnetic forces, however, the notion of action at a distance actually requires a careful inspection of the forces involved and thereby promotes a more detailed analysis of the situation. In this paper, a simple demonstration of Newton's third law is presented in the context of a magnet falling through a hollow conducting tube. The results are unambiguous and lead the students to an irrefutable verification of Newton's third law.
Simple apparatus for the measurement of mechanical properties of solids
Authors: Gomes Ligia R. , Amado Ana , Torres Manuel C. , Santos Luís M. N. B. F.
Published: January 2011

This paper describes a simple apparatus we have developed for determining elastic properties of materials. The easily constructed system may be used to measure the elongation or compression of a sample to which a succession of loads is applied. This allows stress-strain curves to be plotted and analyzed. We describe the construction and use of the apparatus and present some sample data.
Teaching F = ma using a flying saucer toy
Authors: Ogawara Yasuo
Published: January 2011

For beginning students it is often difficult to understand Newton's second law.1,2 I wrote the following question for a mid-term examination.
“Retests”: A better method of test corrections
Authors: McManus Jeff
Published: January 2011

Physics instructors at all levels employ a variety of techniques to encourage students to reflect on and correct mistakes made on quizzes, unit tests, or exams. A thorough analysis of several methods was recently published in these pages that compared several variations of quiz corrections in college courses.1 One common method is to have students rewrite the solutions to the questions or problems that they missed, with the goal of earning some part of the missed points. While this method is helpful for some students, it often discourages students with already decent grades to reflect on their work. I use a method called “retesting” with my AP® Physics C students that I learned from my high school geometry teacher, Bill Kramer. I feel his clever method offers significant advantages over more traditional approaches.
Leukotriene Inflammatory Mediators Meet Their Match
Authors: Funk Colin D.
Published: January 2011

The main enzyme in the leukotriene biosynthesis pathway finally yields to crystallization, paving the way for new leukotriene-modifier drugs.
Novel Peptide to Treat Sepsis-Induced Acute Lung Injury
Authors: Ahmad Shama
Published: January 2011

Inhibition of protein kinase C-δ activity limits acute respiratory distress syndrome–related lung injury.
Comparative
In Vitro
Activities of the Novel Antibacterial Finafloxacin against Selected Gram-Positive and Gram-Negative Bacteria Tested in Mueller-Hinton Broth and Synthetic Urine
Authors: Dalhoff Axel , Stubbings Will , Schubert Sabine
Published: January 2011

Kill kinetics and MICs of finafloxacin and ciprofloxacin against 34 strains with defined resistance mechanisms grown in cation-adjusted Mueller-Hinton broth (CAMHB) at pH values of 7.2 and 5.8 and in synthetic urine at pH 5.8 were determined. In general, finafloxacin gained activity at low pH values in CAMHB and remained almost unchanged in artificial urine. Ciprofloxacin MICs increased and bactericidal activity decreased strain dependently in acidic CAMHB and particularly in artificial urine.
Cross-Resistance to Lincosamides, Streptogramins A, and Pleuromutilins Due to the
lsa
(C) Gene in
Streptococcus agalactiae
UCN70
Authors: Malbruny Brigitte , Werno Anja M. , Murdoch David R. , Leclercq Roland , Cattoir Vincent
Published: January 2011

Streptococcus agalactiae
UCN70, isolated from a vaginal swab obtained in New Zealand, is resistant to lincosamides and streptogramins A (LS
A
phenotype) and also to tiamulin (a pleuromutilin). By whole-genome sequencing, we identified a 5,224-bp chromosomal extra-element that comprised a 1,479-bp open reading frame coding for an ABC protein (492 amino acids) 45% identical to Lsa(A), a protein related to intrinsic LS
A
resistance in
Enterococcus faecalis
. Expression of this novel gene, named
lsa
(C), in
S. agalactiae
BM132 after cloning led to an increase in MICs of lincomycin (0.06 to 4 μg/ml), clindamycin (0.03 to 2 μg/ml), dalfopristin (2 to >32 μg/ml), and tiamulin (0.12 to 32 μg/ml), whereas no change in MICs of erythromycin (0.06 μg/ml), azithromycin (0.03 μg/ml), spiramycin (0.25 μg/ml), telithromycin (0.03 μg/ml), and quinupristin (8 μg/ml) was observed. The phenotype was renamed the LS
A
P phenotype on the basis of cross-resistance to
l
incosamides,
s
treptogramins
A
, and
p
leuromutilins. This gene was also identified in similar genetic environments in 17 other
S. agalactiae
clinical isolates from New Zealand exhibiting the same LS
A
P phenotype, whereas it was absent in susceptible
S. agalactiae
strains. Interestingly, this extra-element was bracketed by a 7-bp duplication of a target site (ATTAGAA), suggesting that this structure was likely a mobile genetic element. In conclusion, we identified a novel gene,
lsa
(C), responsible for the acquired LS
A
P resistance phenotype in
S. agalactiae
. Dissection of the biochemical basis of resistance, as well as demonstration of
in vitro
mobilization of
lsa
(C), remains to be performed.
Experimental Phage Therapy in TreatingKlebsiella pneumoniae-Mediated Liver Abscesses and Bacteremia in Mice
Authors: Hung Chih-Hsin , Kuo Chih-Feng , Wang Chiou-Huey , Wu Ching-Ming , Tsao Nina
Published: January 2011

Intragastric inoculation of mice withKlebsiella pneumoniaecan cause liver abscesses, necrosis of liver tissues, and bacteremia. A newly isolated phage (φNK5) with lytic activity forK. pneumoniaewas used to treatK. pneumoniaeinfection in an intragastric model. Both intraperitoneal and intragastric administration of a single dose of φNK5 lower than 2 × 108PFU at 30 min afterK. pneumoniaeinfection was able to protect mice from death in a dose-dependent manner, but the efficacy achieved with a low dose of φNK5 by intragastric treatment provided the more significant protection. Phage φNK5 administered as late as 24 h afterK. pneumoniaeinoculation was still protective, while intraperitoneal treatment with phage was more efficient than intragastric treatment as a result of the dissemination of bacteria into the circulation at 24 h postinfection. Surveys of bacterial counts for mice treated with φNK5 by the intraperitoneal route revealed that the bacteria were eliminated effectively from both blood and liver tissue.K. pneumoniae-induced liver injury, such as liver necrosis, as well as blood levels of aspartate aminotransferase and alanine aminotransferase and inflammatory cytokine production, was significantly inhibited by φNK5 treatment. These data suggest that a low dose of φNK5 is a potential therapeutic agent forK. pneumoniae-induced liver infection.
Time-Kill Activity of the Streptogramin NXL 103 against Gram-Positive and -Negative Bacteria
Authors: Pankuch Glenn A. , Lin Gengrong , Clark Catherine , Appelbaum Peter C.
Published: January 2011

Against 33 Gram-positive and -negative bacteria, NXL 103 MICs were 0.03 to 1 μg/ml. NXL 103 was bactericidal by 12 h at 2 × MIC against all 5 pneumococci and at 2 × MIC after 24 h against all 5 group A and B β-hemolytic streptococci. NXL 103 was bactericidal against all 8Haemophilus influenzaestrains at 2× MIC and all 5Moraxella catarrhalisstrains at 4× MIC after 24 h but was mainly bacteriostatic against 5 methicillin-resistantStaphylococcus aureusstrains. After the exposure of one strain of each species to NXL 103 for 10 daily subcultures, the MICs remained within ±1 dilution.
In VitroCharacterization of GS-8374, a Novel Phosphonate-Containing Inhibitor of HIV-1 Protease with a Favorable Resistance Profile
Authors: Callebaut Christian , Stray Kirsten , Tsai Luong , Williams Matt , Yang Zheng-Yu , Cannizzaro Carina , Leavitt Stephanie A. , Liu Xiaohong , Wang Kelly , Murray Bernard P. , Mulato Andrew , Hatada Marcos , Priskich Tina , Parkin Neil , Swaminathan Swami , Lee William , He Gong-Xin , Xu Lianhong , Cihlar Tomas
Published: January 2011

GS-8374 is a novel bis-tetrahydrofuran HIV-1 protease (PR) inhibitor (PI) with a unique diethylphosphonate moiety. It was selected from a series of analogs containing various di(alkyl)phosphonate substitutions connected via a linker to theparaposition of a P-1 phenyl ring. GS-8374 inhibits HIV-1 PR with high potency (Ki= 8.1 pM) and with no known effect on host proteases. Kinetic and thermodynamic analysis of GS-8374 binding to PR demonstrated an extremely slow off rate for the inhibitor and favorable contributions of both the enthalpic and entropic components to the total free binding energy. GS-8374 showed potent antiretroviral activity in T-cell lines, primary CD4+T cells (50% effective concentration [EC50] = 3.4 to 11.5 nM), and macrophages (EC50= 25.5 nM) and exhibited low cytotoxicity in multiple human cell types. The antiviral potency of GS-8374 was only moderately affected by human serum protein binding, and its combination with multiple approved antiretrovirals showed synergistic effects. When it was tested in a PhenoSense assay against a panel of 24 patient-derived viruses with high-level PI resistance, GS-8374 showed lower mean EC50s and lower fold resistance than any of the clinically approved PIs. Similar to other PIs,in vitrohepatic microsomal metabolism of GS-8374 was efficiently blocked by ritonavir, suggesting a potential for effective pharmacokinetic boostingin vivo. In summary, results from this broadin vitropharmacological profiling indicate that GS-8374 is a promising candidate to be further assessed as a new antiretroviral agent with potential for clinical efficacy in both treatment-naïve and -experienced patients.
Primary Human Colonic Myofibroblasts Are Resistant toClostridium difficileToxin A-Induced, but Not Toxin B-Induced, Cell Death
Authors: Mullan N. , Hughes K. R. , Mahida Y. R.
Published: January 2011

Colonic inflammation inClostridium difficileinfection is mediated by released toxins A and B. We investigated responses toC. difficiletoxins A and B by isolated primary human colonic myofibroblasts, which represent a distinct subpopulation of mucosal cells that are normally located below the intestinal epithelium. Following incubation with either purified toxin A or B, there was a change in myofibroblast morphology to stellate cells with processes that were immunoreactive for alpha-smooth muscle actin. Most of the myofibroblasts remained viable, with persistence of stellate morphology, despite exposure to high concentrations (up to 10 μg/ml) of toxin A for 72 h. In contrast, a majority of the toxin B-exposed myofibroblasts lost their processes prior to cell death over 24 to 72 h. At low concentrations, toxin A provided protection against toxin B-induced cell death. Within 4 h, myofibroblasts exposed to either toxin A or toxin B lost expression of the nonglucosylated form of Rac1, and there was also a loss of the active form of RhoA. Despite preexposure to high concentrations of toxin A for 3 h, colonic myofibroblasts were able to recover their morphology and proliferative capacity during prolonged culture in medium. However, toxin B-preexposed myofibroblasts were not able to recover. In conclusion, primary human colonic mucosal myofibroblasts are resistant to toxin A (but not toxin B)-induced cell death. Responses by colonic myofibroblasts may play an important role in mucosal protection, repair, and regeneration in colitis due toC. difficileinfection.
Beta Interferon Suppresses the Development of Experimental Cerebral Malaria
Authors: Morrell Craig N. , Srivastava Kalyan , Swaim AnneMarie , Lee M. Teresa , Chen Jun , Nagineni Chandrashakaharam , Hooks John J. , Detrick Barbara
Published: January 2011

Cerebral malaria (CM) is a major complication ofPlasmodium falciparuminfection, particularly in children. The pathogenesis of cerebral malaria involves parasitized red blood cell (RBC)-mediated vascular inflammation, immune stimulation, loss of blood-brain barrier integrity, and obstruction of cerebral capillaries. Therefore, blunting vascular inflammation and immune cell recruitment is crucial in limiting the disease course. Beta interferon (IFN-β) has been used in the treatment of diseases, such as multiple sclerosis (MS) but has not yet been explored in the treatment of CM. Therefore, we sought to determine whether IFN-β also limits disease progression in experimental cerebral malaria (ECM).Plasmodium berghei-infected mice treated with IFN-β died later and showed increased survival, with improved blood-brain barrier function, compared to infected mice. IFN-β did not alter systemic parasitemia. However, we identified multiple action sites that were modified by IFN-β administration.P. bergheiinfection resulted in increased expression of chemokine (C-X-C motif) ligand 9 (CXCL9) in brain vascular endothelial cells that attract T cells to the brain, as well as increased T-cell chemokine (C-X-C motif) receptor 3 (CXCR3) expression. The infection also increased the cellular content of intercellular adhesion molecule 1 (ICAM-1), a molecule important for attachment of parasitized RBCs to the endothelial cell. In this article, we report that IFN-β treatment leads to reduction of CXCL9 and ICAM-1 in the brain, reduction of T-cell CXCR3 expression, and downregulation of serum tumor necrosis factor alpha (TNF-α). In addition, IFN-β-treatedP. berghei-infected mice also had fewer brain T-cell infiltrates, further demonstrating its protective effects. Hence, IFN-β has important anti-inflammatory properties that ameliorate the severity of ECM and prolong mouse survival.
Staphylococcal Alpha-Toxin Is a Strong Inducer of Interleukin-17 in Humans
Authors: Niebuhr Margarete , Gathmann Merle , Scharonow Helena , Mamerow Diana , Mommert Susanne , Balaji Hari , Werfel Thomas
Published: January 2011

Patients with atopic dermatitis (AD) are frequently colonized withStaphylococcus aureus, with one-third of isolates producing alpha-toxin. Moreover,S. aureuscolonization is positively correlated with the severity of eczema. Interleukin-17A (IL-17A) has gained attention in diseases associated with chronic skin infections. The aim of this study was to investigate the effects of sublytic alpha-toxin concentrations on IL-17A production. Sublytic alpha-toxin concentrations strongly induced IL-17A in peripheral blood mononuclear cells (PBMCs), isolated CD4+T cells, polarized Th17 cells, and Th17 clones from reactive atopy patch test lesions and blood from AD patients. Alpha-toxin induced IL-17A directly in T cells. The effect of alpha-toxin was further amplified by upregulation of IL-1 in monocytes. In conclusion, higher levels of IL-17A secretion induced by alpha-toxin in the skin partially explain how colonization withS. aureuscan contribute to chronic skin inflammation.
The Atherogenic BacteriumPorphyromonas gingivalisEvades Circulating Phagocytes by Adhering to Erythrocytes
Authors: Belstrøm Daniel , Holmstrup Palle , Damgaard Christian , Borch Tanja S. , Skjødt Mikkel-Ole , Bendtzen Klaus , Nielsen Claus H.
Published: January 2011

A relationship between periodontitis and coronary heart disease has been investigated intensively. A pathogenic role for the oral bacteriumPorphyromonas gingivalishas been suggested for both diseases. We examined whether complement activation byP. gingivalisstrain ATCC 33277 allows the bacterium to adhere to human red blood cells (RBCs) and thereby evade attack by circulating phagocytes. On incubation with normal human serum, theP. gingivalisstrain efficiently fixed complement component 3 (C3). Incubation of bacteria with washed whole blood cells suspended in autologous serum resulted in a dose- and time-dependent adherence to RBCs. The adherence required functionally intact complement receptor 1 (CR1; also called CD35) on the RBCs and significantly inhibited the uptake ofP. gingivalisby neutrophils and B cells within 1 min of incubation (by 64% and 51%, respectively) and that by monocytes after between 15 min and 30 min of incubation (by 66% and 53%, respectively). The attachment of C3b/iC3b to bacterium-bearing RBCs decreased progressively after 15 min, indicating that conversion of C3 fragments into C3dg occurred, decreasing the affinity for CR1 on RBCs. We propose thatP. gingivalisexploits RBCs as a transport vehicle, rendering it inaccessible to attack by phagocytes, and by doing so plays a role in the development of systemic diseases.
Chlamydial Infection Increases Gonococcal Colonization in a Novel Murine Coinfection Model
Authors: Vonck Rachel A. , Darville T. , O'Connell C. M. , Jerse Ann E.
Published: January 2011

Genital tract infections caused byNeisseria gonorrhoeaeandChlamydia trachomatisserovars D to K occur at high incidence in many areas of the world. Despite high rates of coinfection with these pathogens, investigations of host-parasite interactions have focused on each pathogen individually. We describe here a coinfection model in which female BALB/c mice were first infected with the mouseChlamydiaspeciesC. muridarumand then inoculated withN. gonorrhoeaefollowing treatment with water-soluble 17β-estradiol to promote long-term gonococcal infection. Viable gonococci and chlamydiae were recovered for an average of 8 to 10 days, and diplococci and chlamydial inclusions were observed in lower genital tract tissue by immunohistochemical staining. Estradiol treatment reduced proinflammatory cytokine and chemokine levels in chlamydia-infected mice; however, coinfected mice had a higher percentage of vaginal neutrophils compared to mice infected with either pathogen alone. We detected no difference in pathogen-specific antibody levels due to coinfection. Interestingly, significantly more gonococci were recovered from coinfected mice compared to mice infected withN. gonorrhoeaealone. We found no evidence thatC. muridarumincreases gonococcal adherence to, or invasion of, immortalized murine epithelial cells. However, increased vaginal concentrations of inflammatory mediators macrophage inflammatory protein 2 and tumor necrosis factor alpha were detected inC. muridarum-infected mice prior to inoculation withN. gonorrhoeaeconcurrently with the downregulation of cathelicidin-related antimicrobial peptide and secretory leukocyte peptidase inhibitor genes. We conclude that female mice can be successfully infected with bothC. muridarumandN. gonorrhoeaeand that chlamydia-induced alterations in host innate responses may enhance gonococcal infection.
Cpa, the Outer Membrane Protease ofCronobacter sakazakii, Activates Plasminogen and Mediates Resistance to Serum Bactericidal Activity
Authors: Franco A. A. , Kothary M. H. , Gopinath G. , Jarvis K. G. , Grim C. J. , Hu L. , Datta A. R. , McCardell B. A. , Tall B. D.
Published: January 2011

Cronobacterspp. are emerging neonatal pathogens in humans, associated with outbreaks of meningitis and sepsis. To cause disease, they must survive in blood and invade the central nervous system by penetrating the blood-brain barrier.C. sakazakiiBAA-894 possesses an ∼131-kb plasmid (pESA3) that encodes an outer membrane protease (Cpa) that has significant identity to proteins that belong to the Pla subfamily of omptins. Members of this subfamily of proteins degrade a number of serum proteins, including circulating complement, providing protection from the complement-dependent serum killing. Moreover, proteins of the Pla subfamily can cause uncontrolled plasmin activity by converting plasminogen to plasmin and inactivating the plasmin inhibitor α2-antiplasmin (α2-AP). These reactions enhance the spread and invasion of bacteria in the host. In this study, we found that an isogeniccpamutant showed reduced resistance to serum in comparison to its parentC. sakazakiiBAA-894 strain. Overexpression of Cpa inC. sakazakiiorEscherichia coliDH5α showed that Cpa proteolytically cleaved complement components C3, C3a, and C4b. Furthermore, a strain ofC. sakazakiioverexpressing Cpa caused a rapid activation of plasminogen and inactivation of α2-AP. These results strongly suggest that Cpa may be an important virulence factor involved in serum resistance, as well as in the spread and invasion ofC. sakazakii.
Genome-Scale Identification of Resistance Functions in Pseudomonas aeruginosa Using Tn-seq
Authors: Gallagher Larry A. , Shendure Jay , Manoil Colin
Published: January 2011

We describe a deep-sequencing procedure for tracking large numbers of transposon mutants of
Pseudomonas aeruginosa
. The procedure employs a new Tn-seq methodology based on the generation and amplification of single-strand circles carrying transposon junction sequences (the Tn-seq circle method), a method which can be used with virtually any transposon. The procedure reliably identified more than 100,000 transposon insertions in a single experiment, providing near-saturation coverage of the genome. To test the effectiveness of the procedure for mutant identification, we screened for mutations reducing intrinsic resistance to the aminoglycoside antibiotic tobramycin. Intrinsic tobramycin resistance had been previously analyzed at genome scale using mutant-by-mutant screening and thus provided a benchmark for evaluating the new method. The new Tn-seq procedure identified 117 tobramycin resistance genes, the majority of which were then verified with individual mutants. The group of genes with the strongest mutant phenotypes included nearly all (13 of 14) of those with strong mutant phenotypes identified in the previous screening, as well as a nearly equal number of new genes. The results thus show the effectiveness of the Tn-seq method in defining the genetic basis of a complex resistance trait of
P. aeruginosa
and indicate that it can be used to analyze a variety of growth-related processes.

IMPORTANCE
Research progress in microbiology is technology limited in the sense that the analytical methods available dictate how questions are experimentally addressed and, to some extent, what questions are asked. This report describes a new transposon tracking procedure for defining the genetic basis of growth-related processes in
Pseudomonas aeruginosa
, an important bacterial pathogen. The method employs next-generation sequencing to monitor the makeup of mutant populations (Tn-seq) and has several potential advantages over other Tn-seq methodologies. The new method was validated through the analysis of a clinically relevant antibiotic resistance trait.
A novel method to enhance informed consent: a prospective and randomised trial of form-based versus electronic assisted informed consent in paediatric endoscopy
Authors: Friedlander Joel A , Loeben Greg S , Finnegan Patricia K , Puma Anita E , Zhang Xuemei , de Zoeten Edwin F , Piccoli David A , Mamula Petar
Published: January 2011

Objectives

To evaluate the adequacy of paediatric informed consent and its augmentation by a supplemental computer-based module in paediatric endoscopy.

Methods

The Consent-20 instrument was developed and piloted on 47 subjects. Subsequently, parents of 101 children undergoing first-time, diagnostic upper endoscopy performed under moderate IV sedation were prospectively and consecutively, blinded, randomised and enrolled into two groups that received either standard form-based informed consent or standard form-based informed consent plus a commercial (Emmi Solutions, Inc, Chicago, Il), sixth grade level, interactive learning module (electronic assisted consent). Anonymously and electronically, the subjects' anxiety (State Trait Anxiety Inventory), satisfaction (Modified Group Health Association of America), number of questions asked, and attainment of informed consent were assessed (Consent-20). Statistics were calculated using t test, paired t test, and Mann Whitney tests.

Results

The ability to achieve informed consent, as measured by the new instrument, was 10% in the control form-based consent group and 33% in the electronic assisted consent group (p<0.0001). Electronically assisting form-based informed consent did not alter secondary outcome measures of subject satisfaction, anxiety or number of questions asked in a paediatric endoscopy unit.

Conclusions

This study demonstrates the limitations of form-based informed consent methods for paediatric endoscopy. It also shows that even when necessary information was repeated electronically in a comprehensive and standardised video, informed consent as measured by our instrument was incompletely achieved. The supplemental information did, however, significantly improve understanding in a manner that did not negatively impact workflow, subject anxiety or subject satisfaction. Additional study of informed consent is required.

Clinical trial registration number

ClinicalTrials.gov IdentifierNCT00899392.
Alkaline mafic and ultramafic lamprophyres from the Aillik Bay area, Labrador
Authors: Malpas J. , Foley S. F. , King A. F.
Published: January 2011

The Aillik Bay lamprophyric dyke swarm comprises abundant sannaites, plus rarer olivine sannaites, aillikites and carbonatites. Sannaites are characterized by phenocrysts of Ti–Al titansalite plus rarer olivine and phiogopite in a groundmass dominated by pyroxene, biotite, titanomagnetite, and K-feldspar. Minor mineral phases may include apatite, nepheline, analcime, carbonate, rutile, and pyrite. Most sannaites contain well-developed leucocratic ocelli, which are commonly zoned. Olivine sannaites are similar, but olivine (Fo77–85) is more abundant, and ocelli are rarer. Both types occur together as banded dykes, and calculations support the suggestion of a common parental melt.Aillikites have zoned phenocrysts of olivine (Fo71–87) and mica in a groundmass of carbonate, apatite, mica, titanomagnetite, and perovskite. Carbonatite dykes usually exhibit textures with features akin to those of the aillikites. The mineraiogical and geochemical characteristics of the aillikites are distinct from those of kimberlites.It is the intent of this paper to provide new data on these rocks. These data are used to support one of several viable models for the generation of all dyke-rock types by partial melting of LREE-enriched mantle at depths of 90–110 km. Carbonatite dykes are believed to represent the smallest melt fraction but are the latest emplaced dykes. These small melt fractions may have followed structural weaknesses created by earlier lamprophyre magmatism.
U–Pb geochronology of two augen gneiss terranes, Idaho—new data and tectonic implications
Authors: Evans Karl V. , Fischer Lynn B.
Published: January 2011

U–Pb isotopic analyses of cogenetic zircon suites revise the ages of two augen gneiss terranes in central and northern Idaho. The augen gneiss of Priest River yields an upper-intercept concordia age for only moderately discordant zircons of 1576 ± 13 Ma; there is no evidence of an inherited xenocrystic lead component. Because this unit probably is in basement beneath Belt–Purcell strata, it provides a maximum age for Belt and Purcell sedimentation. However, high-grade metamorphism and structural complexity permit several tectonic interpretations, all of which should be treated with caution pending further detailed studies.Zircons from the augen gneiss of Red River contain inherited radiogenic lead, but by analogy with lithologically and isotopically similar augen gneiss and porphyritic granite near Salmon and Shoup, Idaho, an age of about 1370 Ma is suggested. However, the uncertainty associated with this value is unknown and could be large. Intrusion preceded or was synkinematic with at least part of the deformation and metamorphism that affected the metasedimentary host rocks, thought by some to be Belt–Purcell strata.
Occurrence and possible tectonic significance of high-pressure granulite fragments in the Tulemalu fault zone, District of Keewatin, N.W.T., Canada
Authors: Tella S. , Eade K. E.
Published: January 2011

Fragments of garnet–clinopyroxene granulite with corona textures in ductilely deformed lower-amphibolite-grade quartzofeldspathic granitoid gneiss are exposed within the northeast-trending Tulemalu fault zone. The mineral association of the fragments is garnet–clinopyroxene–plagioclase(An20–An22)–quartz–opaques–hornblende–biotite. Textural evidence suggests that hornblende and biotite are late overgrowth minerals. Garnet and clinopyroxene and (or) hornblende are separated by a narrow rim of plagioclase. Pressure–temperature estimates based on currently used geothermobarometers are of the order of 715–789 °C and 10.2–11.4 kbar (1 kbar = 100 MPa) for the garnet–clinopyroxene–plagioclase–quartz assemblage. The fragments are interpreted as relicts of deep-crustal materials, uplifted to higher levels probably as xenolithic rafts in a granitic melt along the fault zone during late Archean or Early Proterozoic ductile displacements. The growth of hornblende and the development of plagioclase reaction rims around garnet are believed to be due to isothermal decompression reactions during uplift.On the basis of limited geological data, paired gravity anomaly patterns, and aeromagnetic interpolation, the Tulemalu fault zone is postulated as representing the northeasterly extension of the Virgin River – Black Lake fault zones of Saskatchewan and represents an approximately 5 km wide ductile deformation zone that separates an Archean granulite terrane to the west from a relatively lower grade terrane composed of Archean supracrustal rocks to the east.
Lower to Middle Jurassic (Pliensbachian to Bajocian) stratigraphy of the northern Spatsizi area, north-central British Columbia
Authors: Thomson Robert C. , Smith Paul L. , Tipper Howard W.
Published: January 2011

The Lower to Middle Jurassic (Pliensbachian to lower Bajocian) Spatsizi Group in the northern Spatsizi area of north-central British Columbia is formally defined and subdivided into the Joan, Wolf Den, Melisson, Abou, and Quock formations. Each formation reflects deposition in a different, dominantly fine-clastic environment with a varying input of volcanic (epiclastic or pyroclastic) detritus. The Spatsizi Group represents the basinward sedimentary equivalent of the coeval Cold Fish Volcanics, a group of calc-alkaline flows and breccias that accumulated in a volcanic arc along the southern flank of the Stikine Arch. Arc-to basin-facies trends are best developed in the Joan and Wolf Den formations and are characterized by a decrease in the volcaniclastic component of the sediments, an overall reduction in grain size, and a progressively deeper water environment of deposition, as inferred from both sedimentological and faunal evidence.In the study area, the Spatsizi Group underlies with a slight angular discordance the Middle to Upper Jurassic Bowser Lake Group. Bowser lake sediments were deposited in the Bowser Basin, the largest Mesozoic successor basin in British Columbia. Based on evidence from the Spatsizi area and from other areas to the south at Diagonal Mountain and the Oweegee Mountains, the Spatsizi Group is interpreted as passing laterally into shales that underlie most of the Bowser Basin.
Identification and significance of tephras encountered in a core from Mary Lake, Yoho National Park, British Columbia
Authors: Reasoner Mel A. , Healy Raymond E.
Published: January 2011

Mary Lake is a small, subalpine lake located proximal (<3 km) to the Continental Divide near Lake O'Hara in Yoho National Park, British Columbia. A 1.25 m core recovered from surficial bottom sediments was found to contain both Bridge River tephra (2350 years BP) and Mazama tephra (6800 years BP). Identification of the tephras was initially based on distinctive colour, texture, phenocryst assemblages, and glass shard habits and was confirmed by electron microprobe analysis of the constituent glass shards. The microprobe technique employed backscattered and secondary electron imagery and both energy dispersive and wavelength dispersive analyses.Mean annual sedimentation rates calculated from tephra depths in the Mary Lake core were found to be of the order of 0.15 mm/year for the post-Bridge River time period and 0.02 mm/year for the Mazama – Bridge River interval. The preservation of Mazama tephra in Mary Lake lacustrine sediments indicates that deglaciation had proceeded upvalley from the Mary Lake basin prior to 6800 years BP, and consequently, moraine systems exposed downvalley are pre-Mazama in age.
Striding-Athabasca mylonite zone: Complex Archean deep-crustal deformation in the East Athabasca mylonite triangle, northern Saskatchewan
Authors: Hanmer Simon , Parrish Randy , Williams Michael , Kopf Chris
Published: January 2011

The geophysically defined Snowbird tectonic zone is manifested in northernmost Saskatchewan as a deep-crustal, multistage mylonitic structure, the East Athabasca mylonite triangle. The triangle, located at the northeastern apex of a stiff, crustal-scale "lozenge," is composed of mid-Archean annealed mylonites and late Archean ribbon mylonites, formed during two granulite facies events (850–1000 °C, 1.0 GPa). The flow pattern in the mylonites is geometrically and kinematically complex, and corresponds to that expected adjacent to the apex of a stiff elliptical volume subjected to subhorizontal regional extension parallel to its principal axis. The late Archean mylonites are divided into an upper structural deck, entirely occupied by a dip-slip shear zone, and an underlying lower deck. The latter is divided into two upright conjugate strike-slip shear zones, separated by a low-strain septum, which deformed by progressive coaxial flow. The flow pattern in the mid-Archean mylonites is compatible with that of the late Archean mylonites, and suggests that the crustal-scale lozenge influenced deformation since the mid-Archean. In the interval ca. 2.62–2.60 Ga, deformation in the upper and lower decks evolved from a granulite facies pervasive regime to a more localized amphibolite facies regime. With further cooling, deformation was localized within very narrow greenschist mylonitic faults at the lateral limits of the lower deck. By the late Archean, the East Athabasca mylonite triangle was part of a deep-crustal, intracontinental shear zone. This segment of the Snowbird tectonic zone was not the site of an Early Proterozoic suture or orogen.
Kinematic evolution of metre-scale shear zones in foliated low-grade tectonites: an example from the Bousquet gold district, Quebec
Authors: Tourigny Ghislain , Chartrand Francis
Published: January 2011

Small-scale subvertical shear zones developed parallel to a regional preexisting S2 schistosity exhibit evidence of a complex shearing history recorded by conflicting kinematic indicators in both crosssection and plan view. The concordant schistosity internal to the shear zones contains a steeply plunging stretching lineation. Coexisting kinematic indicators of non-coaxial deformation parallel to this lineation are compatible with reverse dip-slip. This earliest shearing event was characterized by (1) the development of several shear discontinuities along selected preexisting S2 foliation surfaces, (2) subvertical transposition of both bedding and the oldest (S1) flat-lying foliation, and (3) by the emplacement of shear veins along the S2 foliation planes. The youngest shearing event reactivated the foliation-parallel shear discontinuities as dextral shear planes, thereby causing concomitant subhorizontal retransposition, east–west subhorizontal stretching, and emplacement of en echelon extension veins. A single set of shear bands occurring at a clockwise acute angle to the slipping foliation indicates that small-scale shear zones were transpressional during the late dextral shearing.
Effet de la vitesse de refroidissement sur l'intensité de l'aimantation thermorémanente: étude expérimentale, conséquences théoriques
Authors: Biquand Daniel
Published: January 2011

The experiments reported here compare intensity and thermal resistance of two thermal remanent magnetizations (TRM), successively acquired by the same sample under a magnetic field, but at two different cooling speeds. The samples (one with a base of CrO2 powder, and the others derived from oceanic basalts) were representative of the different types of structure domains characteristic of magnetic grains. The experimental procedure established aimed at limiting the various factors of uncertainty: mineralogical and structural modifications related to heating; inhomogeneity of the sample temperature at crucial stages of each experiment; effects of undesirable magnetizations acquired concurrently with the TRM. The main conclusion of this study is that the TRM intensity increases as a function of time of cooling, independently of the types of structure domains carried by the magnetic grains. The greatest effect is with the CrO2 monodomain: the TRM obtained between 130 and 100 °C during a cooling period of 120 h was 19% superior to the one obtained during a passive cooling period of 30 min for the same temperature limits, the measurements having been taken at 50 °C. Both types of oceanic samples analyzed (pseudo-monodomains and multidomains) showed a similar relative variation, but that much weaker. For example, the TRM induced on cooling from 200 to 50 °C (120 h) provided values only 6% higher than the one obtained during passive cooling (periods of 30–40 min). The theoretical implications of these results are discussed. [Journal Translation]
Geochronological constraints on late Archean magmatism deformation and gold–quartz vein mineralization in the northwestern Anialik River greenstone belt and igneous complex, Slave Province, N.W.T.
Authors: Abraham A. P. G. , Davis D. W. , Kamo S. L. , Spooner E. T. C.
Published: January 2011

Three phases of the Anialik River igneous complex (ARIC) give U–Pb zircon ages in the range −2705–2683 Ma, and three units from the adjacent northwestern Anialik River greenstone belt (ARGB) give ca. 2678 Ma ages. Titanite from unsheared ARIC rocks crystallized during localized metamorphism and deuteric alteration between 2693 and 2683 Ma. Hydrothermal titanite in wall rocks to gold-mineralized shear zones crystallized during early shear zone development (2670 ± 1 Ma) and was subsequently locally altered to rutile, with gold occurring within the rutile-bearing assemblage. Unaltered second-generation hydrothermal titanite, overgrowing the rutile assemblage, crystallized during later brittle–ductile movement (2656 ± 2 Ma) and provides a minimum age for gold mineralization. Relatively high 207Pb/204Pb ratios of Pb in gold-associated galena suggest that it was partly derived from significantly older crustal material, possibly underlying the igneous complex and greenstone belt. This interpretation is consistent with other evidence for the existence of > 3.0 Ga crustal rocks to the west of the study area. A late crosscutting granite gives an age of [Formula: see text] and is therefore part of the Pan-Slave tectono-thermal event. These results, and other data for the Slave Province, indicate temporal variations in the development and deformation of predeformational greenstone belts. The new ages show that regional deformation and metamorphism in the northwestern Slave Province followed shortly after major magmatism, and that gold mineralization might have occurred during the late Archean accretion of the greenstone belt and igneous complex to an older crustal domain to the west.
Fine structure of helium and light helium-like ionsThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010.
Authors: Pachucki Krzysztof , Yerokhin Vladimir A.
Published: January 2011

Calculational results are presented for the fine structure splitting of the 23P state of helium and helium-like ions with nuclear charge Z up to 10. Theoretical predictions are in agreement with the latest experimental results for the helium fine structure intervals as well as with the most of the experimental data available for light helium-like ions. Comparing the theoretical value of the 23P0-23P1 interval in helium with experimental results (Zelevinsky et al. Phys. Rev. Lett. 95, 203001 (2005)), we determine the value of the fine structure constant α with an accuracy of 31 ppb.
Semiclassical approach to the line shapeThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010.
Authors: Stoilov M. N.
Published: January 2011

We extend the results of Bakalov et al. (Phys. Rev. Lett. 84, 2350 (2000)) on one-photon electric dipole transition line shift and broadening to the case of two-photon transitions. As an example, we consider the laser-induced transition in antiprotonic helium produced in a helium gas target. The transition is between antiprotonic helium states (n, l) = (33, 32) and (31, 30).
Progress in precise laser spectroscopy of antiprotonic helium atomsThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010.
Authors: Hori Masaki
Published: January 2011

The ASACUSA collaboration at CERN has previously measured the optical transition frequencies of antiprotonic helium to a precision of <1 part in 108 by laser spectroscopy. We describe some recent theoretical and experimental developmental work carried out by our collaboration to further improve the experimental precision.
Theoretical progress in the H2+ molecular ion: towards electron to proton mass ratio determinationThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010.
Authors: Karr J.-Ph. , Hilico L. , Korobov V. I.
Published: January 2011

High resolution ro-vibrational spectroscopy of H 2+ or HD+ can lead to a significantly improved determination of the electron to proton mass ratio me/mp if the theoretical determination of transition frequencies becomes sufficiently accurate. We report on recent theoretical progress in the description of the hyperfine structure of H 2+ , as well as first steps in the evaluation of radiative corrections at order mα7. Completion of the latter calculation should allow us to reach the projected 10−10 accuracy level and open the road to mass ratio determination.
Relativistic corrections to He I transition ratesThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010.
Authors: Morton Donald C. , Moffatt Paul , Drake G. W.F.
Published: January 2011

The relativistic corrections to the theoretical oscillator strengths of light elements such as helium are typically less than 0.1% and usually are ignored. However, they can be important for comparisons with the most accurate experiments, and they rapidly increase in magnitude with increasing nuclear charge. We have begun with the spin-forbidden electric-dipole transitions of neutral helium, using calculations consisting of (1) extremely accurate wave functions without relativistic corrections for both infinite and finite nuclear mass, (2) spin-changing matrix elements through the perturbations of the wave functions by the spin-orbit and spin-other-orbit Breit operators, (3) the use of pseudostates in the sums over all the intermediate states including the continuum, and (4) the inclusion as perturbers of the 1S0 and 3S1 states the pseudostates corresponding to the doubly excited npn′p 3P 0e and npn′p 1P 1e terms, respectively. As examples of these calculations, we present oscillator strengths for the transitions 1 1S0–2 3P1, 2 1S0–2 3P1, 2 3S1–2 1P1, 2 1P1–3 3D1,2, and 2 3P1,2–3 1D2.
The vacuum magnetic birefringence experiment: a test for quantum electrodynamicsThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010.
Authors: Berceau P. , Battesti R. , Fouché M. , Rizzo C.
Published: January 2011

In this contribution to PSAS 2010 we describe the status of the BMV experiment whose goal is to measure the vacuum magnetic birefringence that would represent a pure test for quantum electrodynamics. We present our latest experimental data obtained from Cotton–Mouton measurements of different gases.
Hyperfine interaction effects on the (1s2p)3P1–(1s2s)1S0 energy splitting in He-like ions for parity nonconservation studiesThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010.
Authors: Ferro Fabrizio , Artemyev Anton , Surzhykov Andrey , Stöhlker Thomas
Published: January 2011

Accurate theoretical knowledge of the (1s2p)3P1–(1s2s)1S0 splitting in He-like ions is demanded for future experimental studies of the nuclear spin-dependent part of the weak interaction. In this paper we perform a calculation of the hyperfine structure of (1s2p)3P1–(1s2s)1S0 within 3 ≤ Z ≤ 35, Z being the atomic number. In this Z range parity nonconservation (PNC) effects are amplified by the close energy proximity of the opposite parity levels (1s2p)3P1 and (1s2s)1S0. We find that the hyperfine structure is relevant for Z > 12, and produces splitting among the hyperfine sublevels as large as 150 meV for medium Z He-like ions (Z ∼ 35).