bluuebunny/crossref_metadata_2025 huggingface dataset:
Sci‐AM1 Sat ‐ 04: Gamma‐camera verification of breast brachytherapy seed distributions
Authors: Ravi A , Caldwell C , Keller B , Reznik A , Beachey D , Pignol J
Published: April 2013

Objective: To assess whether a proposed SPECT device could resolve implanted breast brachytherapy seeds within an acceptable imaging time for correction of misplaced seeds. Method: Monte Carlo simulations of a cadmium zinc telluride crystal‐based gamma camera were used to assess whether the detection of 22 keV photons emitted from seeds was feasible. A 5×5 cm detector, fitted with a hexagonal parallel hole collimator (hole length 38 mm, diameter 1.2 mm, septa 0.2 mm) was modeled. Projections were taken every 7.5 degrees, with a radius of rotation of 10 cm, and images reconstructed using an OSEM algorithm. The phantom modeled consisted of an 8 cm diameter sphere of breast tissue containing a central, 1 cm cubic distribution of 8 seeds, which were each 5 mm long and 0.8 mm wide titanium tubes with an inner radius of 0.32 mm. Results: An acquisition duration of 24 seconds yielded images with a FWHM of 6.0 mm and a scatter fraction of 8.2%. The error between the center of mass of the reconstructed image and the physical seed location was 0.81 ± 0.16 mm, when the phantom was imaged for 24 seconds. Conclusion: The online gamma‐camera approach to imaging the seeds is feasible for a simple seed distribution. The high contrast between the seeds and the non‐radioactive background allow a practical acquisition time of a minute or less. Additional simulations will be required to assess the system design for more realistic seed distributions in a geometry more closely modeling a patient.
Sci‐AM1 Sat ‐ 09: Embolization materials affect subsequent radiosurgery dose to AVM's
Authors: Beachey D , Scora D , Ramani M , Andrade‐Souza Y , Schwartz M , Tsao M , terBrugge K
Published: April 2013

Radiosurgery, often used as a follow‐up modality to surgical glue embolization for arterio‐venous‐malformations (AVM's), can be complicated by the polymerizing and contrast agents, Embucrilate and Lipiodol. Post the embolization attempt, these agents remain in the AVM nidus where they depart radiologically from tissue equivalence and thereby affect dose. A test phantom consisting of an array of deposits of embolization medium of both varying thickness and polymer / contrast concentration imbedded in solid water was constructed. For irradiation, the phantom is further imbedded in solid water at positions upstream and downstream relative to a fixed nominal target / film plane at 100 cm SAD (overall phantom thickness: 22cm; film depth: 7.0 cm.) The film placement relative to the glue media interfaces are upstream: −0.2 and 0.0 cm; and downstream: 0.0, 0.2, and 0.5 cm. Irradiations are conducted using a 5 MV radiosurgery beam (Linac system) in a wide (10 cm × 10 cm) SAD‐field setting to encompass the phantom's glue wells. Correspondence of results with narrower coned RS fields was verified. XV film results indicated dose downstream of the interface at 0.0, 0.2, and 0.5 cm was reduced 14% (±3%), 7% (±2%), and 2% (±1%) respectively. The Lipiodol concentrations, (80%, 50%, 20% by weight) reduced maximum dose 16% (±1%), 15% (±1%), and 10% (±1%) respectively. Glue depth and thickness yielded little relative dose effect. Radiation transport calculations and radiochromic film results will also be presented.
Sci‐AM2 Sat ‐ 04: Rotating aperture optimization
Authors: Milette M , Otto K
Published: April 2013

IMRT treatment plans are conventionally produced by the optimization of fluence maps followed by a leaf sequencing step. An alternative approach to fluence based dose optimization is to optimize directly the leaf positions and weights of the segmented fields. This approach is referred to as direct aperture optimization. Here we describe a direct aperture optimization algorithm in which the entire MLC is rotated between each segment field. We call our approach Rotating Aperture Optimization (RAO). The advantages of collimator rotation in IMRT include higher spatial resolution, more flexibility in the generation of aperture shapes and less interleaf error. Since leaf positions are optimized directly, MLC constraints are taken into account during the optimization. Additional constraints like minimum aperture area for each segment shape can also be added. The number of segments per beam is specified by the user. We have tested our RAO algorithm on a complex c‐shape target, a prostate cancer patient and a nasopharynx carcinoma patient. DVH comparisons show that RAO produces highly conformal plans with only 6 segments per beam angle. We show that setting a minimum aperture size for each segment leads to more efficient delivery without compromising the quality of the dose distribution. Our results also show a significant reduction in the number of MU (40% for the nasopharynx and 27% for the prostate) when compared with a fluence based collimator rotated leaf sequencing technique. This work was supported in part by Varian Medical Systems.
Sci‐AM2 Sat ‐ 06: IMRT prostate planning‐determination of the minimum MU/segment
Authors: Grigorov G , Chow J , Barnett R
Published: April 2013

For step and shoot IMRT, the combination of high dose rate, multiple beam segments and low dose per segment can lead to significant differences between the planned and delivered dose to the patient. This problem, known as an “overshoot” effect, is the result of current dose servo limitations and is demonstrated by over‐ and under‐dose in the first and the last segment respectively. Segment dose inaccuracy in the range of 10 to 60% of the both segments for 1 monitor unit (MU) per segment irradiated with dose rate (DR) of 100 to 600 MU/min was measured. The object of this study was to find a method for segment dose correction when small MU and high DR are used, and specify the prostate IMRT planning limits for MU/segment and the DR. The reported results were obtained using Pinnacle3‐V6 and Varian Clinac 2100 EX linear accelerator equipped with a 120‐leaf millennium MLC. The methodology for correcting dose employs small field segment dose ratio. The segment dose error after correction was measured to be less than 5 % for all dose rates. For prostate step and shoot IMRT a low limit of 1 MU per segment and DR with upper limit of 600 MU/min can be used. The results of this work relate to the agreement between planned and delivered doses of the prostate IMRT.
Sci‐AM2 Sat ‐ 07: Development of inverse planning and limited angle CT reconstruction for cobalt‐60 tomotherapy
Authors: Chng N , Kerr A , Rogers M , Schreiner J
Published: April 2013

A significant amount of evidence exists to suggest that Cobalt‐60 can be used to deliver conformal treatments with intensity modulated tomotherapy and on‐line image guidance with megavoltage CT. The purpose of this paper is to describe our recent advances in developing the potential for Cobalt‐60 as a modality for tomotherapy. In particular, we have been advancing forward and inverse planning designed especially for our benchtop delivery configuration, on‐line image reconstruction for Cobalt‐60 CT, and approaches to dose reconstruction. Treatment planning is performed by dose optimization under implicit dose‐volume constraints for a slice using a gradient based inverse algorithm. Although a least‐squares framework is maintained in the explicit objective function for rapid convergence, regional weightings evolve over time to attempt to accommodate dose‐volume constraints. The selection of the appropriate relative region weightings in the objective function is handled internally to improve ease‐of‐use. Simulated plans under a variety of dose‐volume constraints reach reasonable solutions in a matter of minutes. The second area of focus has been in the creation of a CT method that is amenable to the deficiencies of image reconstruction under the inherently limited set of treatment data, while maintaining a high speed of reconstruction necessary for on‐line registration. A one‐step reconstruction method belonging to the class of algebraic reconstruction techniques (ART) is being tested and has shown promise in providing a compromise between the limited‐view qualities of iterative ART and the high reconstruction speed of filtered back‐projection.
Sci‐AM2 Sat ‐ 08: Impact of volume definition on prescribed dose in a liver cancer dose escalation study
Authors: Craig T , Bissonnette J , Eccles C , Dawson L
Published: April 2013

The volume of irradiated liver is strongly related to target volume size in extracranial stereotactic radiation therapy (ESRT) of liver tumours. Our ESRT dose escalation study treats liver cancer with prescription doses that are individualized to maintain a constant risk of radiation induced liver disease (RILD) for all patients. The impact of liver volume on normal tissue complication probability (NTCP) calculation was assessed using the whole liver, liver minus gross tumour volume (GTV), liver minus clinical target volume (CTV), and liver minus planning target volume (PTV). Assuming that liver minus GTV is the most appropriate volume to base NTCP on (since it includes all potentially functional liver), each volume was used to calculate the dose for 5% NTCP. NTCP was then recalculated using the liver minus GTV, but with doses determined from the other liver volumes. The relationship between target volume size and dose is also investigated. NTCP calculated with liver minus CTV or liver minus PTV results in extremely high risks of RILD, while using whole liver underestimates the risk and is safer. For all target volumes, the prescription dose can be increased as the target size decreases. Predicted dose for individualized dose escalation for liver cancer is strongly dependent on the liver volume analyzed. We suggest that liver minus CTV and liver minus PTV volumes cannot safely be used to individualize prescription doses for dose escalation for liver cancer. Based on these substantial changes in NTCP, uniform reporting of volumes and NTCP is desirable.
Sci‐PM Sat ‐ 04: Characterization of a tissue equivalent plastic scintillator dosimetry system
Authors: Petric M , Robar J , Clark B
Published: April 2013

High precision techniques in radiation therapy such as IMRT offer the potential for improved target coverage and increased normal tissue sparing. The complex fluence maps used in many of these techniques, however, lead to more challenging quality assurance with dose verification being labor‐intensive and time consuming. We have developed a dose verification system using tissue equivalent plastic scintillator that provides easy to acquire, rapid electronic and directly digital dose measurements in a plane perpendicular to the beam. The prototype system consists of a water‐filled Lucite phantom with a scintillator screen built into the top surface. The phantom contains a plastic mirror to reflect scintillation light towards a viewing window where it is captured using a CCD camera and a personal computer. Optical photon spread is removed using a micro‐louvre optical collimator and by deconvolving a glare kernel from the raw images. System characterization tests indicate excellent dose and spatial linearity. The system was found to have good signal uniformity and to be independent of dose rate. Spatial resolution was determined to be 0.53 mm/pixel. The system's ability to verify a dynamic treatment field was evaluated using a 60° enhanced dynamic wedge and comparing the results to 2‐D film dosimetry. Results indicate agreement within 5% of 2‐D film dosimetry. With further development this system promises to provide a fast, directly digital, and tissue equivalent alternative to current dose verification systems.
Sci‐PM Sat ‐ 06: Investigating dose resolution in CT polymer gel dosimetry
Authors: Hilts M , Duzenli C , Jirasek A
Published: April 2013

X‐ray computed tomography (CT) is a novel method of extracting 3D dose information from irradiated polymer gels and presents an exciting possibility for widespread clinical application of gel dosimetry. However, clinical use remains limited due, in part, to poor dose resolution. This work investigates dose resolution in CT polyacrylamide gel (PAG) dosimetry and provides optimization strategies for improving dose resolution. In addition, using current PAG formulations, achievable dose resolution is calculated for a range of voxel sizes given a 1 hour imaging time constraint. Phantom design, imaging protocol and voxel size are all shown to be important considerations for improving dose resolution due to their effects on image noise. Specific recommendations include: minimizing phantom size, maximizing tube voltage, using standard or soft reconstruction algorithms and increasing voxel size where clinically appropriate. Dose resolution also depends on the sensitivity and dose range of the gel CT to dose response and for PAGs a 50%C (cross‐linking fraction) gel is shown to provide the best dose resolution. With technique optimization dose resolutions of < 3% for region of interest imaging and ∼ 5% for volume imaging (2.5×2.5×3mm3 voxel size) can be obtained. These results approach those of MRI and OCT gel dosimetry within a shorter (⩽ 1hr) imaging time and highlight the potential for CT gel dosimetry to be a clinically successful 3D dosimetry tool. Future work remains in developing gels more sensitive to CT read‐out and implementing multi‐slice CT imaging, advances which stand to further increase the quality of CT gel dosimetry.
Sci‐PM Sat ‐ 08: Feasibility of gated helical tomotherapy using the real‐time position management (RPM) system
Authors: Kim B , Kron T , Chen J , Yartsev S , Gaede S , Van Dyk J , Battista J
Published: April 2013

We propose a new method of gating helical tomotherapy (HT) delivery for lung lesions that does not require breath holding. Without interrupting the gantry rotation and couch translation, the complete closure of the bMLC leaves would be triggered by the Real Time Position Management (RPM) system (Varian Oncology Systems, Palo Alto, CA), whenever the associated chest (and implied tumour) position moves outside the gating window. Once the initial radiation delivery is complete, additional iterations of the helical treatment are repeated until >95 % of the planned beam projections are delivered. Each iteration commences at a different phase of the respiratory cycle to “fill in” the previously undelivered beam projections. In this study, a gated HT delivery was simulated on the HT unit by delivering a series of “modified” leaf sinograms — altered according to the RPM curve of a real lung patient. The original leaf sinogram created for a stationary target (non‐gated) was modified such that all beam projections whose delivery times fall outside the gating window were nulled. The resulting dose distribution was measured by film dosimetry, and compared to the dose distribution of the non‐gated delivery. The gated HT delivery showed excellent agreement with the non‐gated HT delivery, with a mean dose difference of less than 1% observed in the central plane. In conclusion, the feasibility of gated HT delivery using the RPM system has been demonstrated. Future work will address different breathing patterns and more complicated target shapes treated with intensity modulation.
Sci‐PM Sat ‐ 09: Respiratory gating in cancer applications, including 4‐D CT based treatment planning
Authors: Gaede S , Carnes G , Yu E , Battista J , Lee T
Published: April 2013

Respiratory gating is one way to compensate for organs and/or tumours that are affected by respiratory motion. One approach to respiratory gating is to use the Real‐Time Position Management (RPM) Respiratory Gating System, by Varian Medical Systems, which records the cyclic motion of the chest or abdomen using fiducial skin markers while patients breathe freely. There is conflicting evidence, however, regarding the prediction of internal organ motion with external motion. Moreover, treatment planning is typically based on helical CT scans that are also acquired while patients breathe freely. Consequently, the relative position of the exterior body, the target, and the critical organs at any one phase of a breathing cycle cannot be determined accurately, and the choice of the “beam on” time could lead to error. We have developed a method in acquiring a 4‐D CT data set without the aid of external markers. Instead, the method registers images based on internal correlation at tissue interfaces between two successive respiratory phases. The 3‐D motion of the exterior body and internal organs/tumours can be derived and correlated with the RPM signal if acquired simultaneously. If strong correlation exists, then the set of images can be used for detailed treatment planning to determine the optimal treatment phase of the breathing cycle. Eighteen patients have been imaged with 4‐D CT, and one has been treated with 4‐D CT based respiratory gating. We present our results in the context of the first lung cancer patient in our clinic that was treated with this method.
Characterization of pKP1433, a Novel KPC-2-Encoding Plasmid from Klebsiella pneumoniae Sequence Type 340
Authors: Papagiannitsis C. C. , Miriagou V. , Giakkoupi P. , Tzouvelekis L. S. , Vatopoulos A. C.
Published: April 2013

The nucleotide sequence of pKP1433 (55,417 bp), a
bla
KPC-2
-carrying plasmid from
Klebsiella pneumoniae
sequence type 340, was determined. pKP1433 displayed extensive sequence and structural similarities with the IncN plasmids possessing the KPC-2-encoding Tn
4401b
isoform. However, the replication, partitioning, and stability of pKP1433 were determined by sequences related to diverse non-IncN plasmids.
Is Azole Resistance in Aspergillus fumigatus a Problem in Spain?
Authors: Escribano Pilar , Peláez Teresa , Muñoz Patricia , Bouza Emilio , Guinea Jesús
Published: April 2013

Aspergillus fumigatus
complex comprises
A. fumigatus
and other morphologically indistinguishable cryptic species. We retrospectively studied 362
A. fumigatus
complex isolates (353 samples) from 150 patients with proven or probable invasive aspergillosis or aspergilloma (2, 121, and 6 samples, respectively) admitted to the hospital from 1999 to 2011. Isolates were identified using the β-tubulin gene, and only 1 isolate per species found in each sample was selected. Antifungal susceptibility to azoles was determined using the CLSI M38-A2 procedure. Isolates were considered resistant if they showed an MIC above the breakpoints for itraconazole, voriconazole, or posaconazole (>2, >2, or >0.5 μg/ml). Most of the samples yielded only 1 species (
A. fumigatus
[
n
= 335],
A. novofumigatus
[
n
= 4],
A. lentulus
[
n
= 3],
A. viridinutans
[
n
= 1], and
Neosartorya udagawae
[
n
= 1]). The remaining samples yielded a combination of 2 species. Most of the patients were infected by a single species (
A. fumigatus
[
n
= 143] or
A. lentulus
[
n
= 2]). The remaining 5 patients were coinfected with multiple
A. fumigatus
complex species, although
A. fumigatus
was always involved; 4 of the 5 patients were diagnosed in 2009 or later. Cryptic species were less susceptible than
A. fumigatus
. The frequency of resistance among
A. fumigatus
complex and
A. fumigatus
to itraconazole, voriconazole, and posaconazole was 2.5 and 0.3%, 3.1 and 0.3%, and 4.2 and 1.8%, respectively, in the per-isolate analysis and 1.3 and 0.7%, 2.6 and 0.7%, and 6 and 4% in the per-patient analysis. Only 1 of the 6
A. fumigatus
isolates in which the
cyp51A
gene was sequenced had a mutation at position G448. The proportion of patients infected by azole-resistant
A. fumigatus
isolates was low.
Emergence of Colistin Resistance in Enterobacteriaceae after the Introduction of Selective Digestive Tract Decontamination in an Intensive Care Unit
Authors: Halaby Teysir , al Naiemi Nashwan , Kluytmans Jan , van der Palen Job , Vandenbroucke-Grauls Christina M. J. E.
Published: April 2013

Selective decontamination of the digestive tract (SDD) selectively eradicates aerobic Gram-negative bacteria (AGNB) by the enteral administration of oral nonabsorbable antimicrobial agents, i.e., colistin and tobramycin. We retrospectively investigated the impact of SDD, applied for 5 years as part of an infection control program for the control of an outbreak with extended-spectrum beta-lactamase (ESBL)-producing
Klebsiella pneumoniae
in an intensive care unit (ICU), on resistance among AGNB. Colistin MICs were determined on stored ESBL-producing
K. pneumoniae
isolates using the Etest. The occurrence of both tobramycin resistance among pathogens intrinsically resistant to colistin (CIR) and bacteremia caused by ESBL-producing
K. pneumoniae
and CIR were investigated. Of the 134 retested ESBL-producing
K. pneumoniae
isolates, 28 were isolated before SDD was started, and all had MICs of <1.5 mg/liter. For the remaining 106 isolated after starting SDD, MICs ranged between 0.5 and 24 mg/liter. Tobramycin-resistant CIR isolates were found sporadically before the introduction of SDD, but their prevalence increased immediately afterward. Segmented regression analysis showed a highly significant relationship between SDD and resistance to tobramycin. Five patients were identified with bacteremia caused by ESBL-producing
K. pneumoniae
before SDD and 9 patients thereafter. No bacteremia caused by CIR was found before SDD, but its occurrence increased to 26 after the introduction of SDD. In conclusion, colistin resistance among ESBL-producing
K. pneumoniae
isolates emerged rapidly after SDD. In addition, both the occurrence and the proportion of tobramycin resistance among CIR increased under the use of SDD. SDD should not be applied in outbreak settings when resistant bacteria are prevalent.
Innate Recognition by Neutrophil Granulocytes Differs between Neisseria gonorrhoeae Strains Causing Local or Disseminating Infections
Authors: Roth Alexandra , Mattheis Corinna , Muenzner Petra , Unemo Magnus , Hauck Christof R.
Published: April 2013

Members of the carcinoembryonic antigen-related cell adhesion molecule (CEACAM) family serve as cellular receptors for
Neisseria gonorrhoeae
. More specifically, neisserial colony opacity (Opa
CEA
) proteins bind to epithelial CEACAMs (CEACAM1, CEA, CEACAM6) to promote bacterial colonization of the mucosa. In contrast, recognition by CEACAM3, expressed by human granulocytes, results in uptake and destruction of Opa
CEA
-expressing bacteria. Therefore, CEACAM3-mediated uptake might limit the spread of gonococci. However, some strains can cause disseminating gonococcal infections (DGIs), and it is currently unknown how these strains escape detection by granulocyte CEACAM3. Therefore, the
opa
gene loci from
N. gonorrhoeae
strain VP1, which was derived from a patient with disseminated gonococcal disease, were cloned and constitutively expressed in
Escherichia coli
. Similar to Opa proteins of the nondisseminating strain MS11, the majority of Opa proteins from strain VP1 bound epithelial CEACAMs and promoted CEACAM-initiated responses by epithelial cells. In sharp contrast to the Opa proteins of strain MS11, the Opa proteins of strain VP1 failed to interact with the human granulocyte receptor CEACAM3. Accordingly, bacteria expressing VP1 Opa proteins were not taken up by primary human granulocytes and did not trigger a strong oxidative burst. Analysis of Opa variants from four additional clinical DGI isolates again demonstrated a lack of CEACAM3 binding. In summary, our results reveal that particular
N. gonorrhoeae
strains express an Opa protein repertoire allowing engagement of epithelial CEACAMs for successful mucosal colonization, while avoiding recognition and elimination via CEACAM3-mediated phagocytosis. A failure of CEACAM3-mediated innate immune detection might be linked to the ability of gonococci to cause disseminated infections.
IgG and IgE Collaboratively Accelerate Expulsion of Strongyloides venezuelensis in a Primary Infection
Authors: Matsumoto Makoto , Sasaki Yuki , Yasuda Koubun , Takai Toshiyuki , Muramatsu Masamichi , Yoshimoto Tomohiro , Nakanishi Kenji
Published: April 2013

The host deploys a subset of immune responses to expel helminths, which differs depending on the nature of the helminth.Strongyloides venezuelensis, a counterpart of the human pathogenS. stercoralis, naturally infects rodents and has been used as an experimental model. Here we show that induction of immunoglobulin G (IgG) and IgE is a prerequisite for rapid expulsion ofS. venezuelensisduring a primary infection. Activation-induced cytidine deaminase-deficient (AID−/−) mice, which lack the ability to switch IgM to other isotypes, normally developed T-helper 2 (Th2) cells and intestinal mastocytosis after infection withS. venezuelensis. Although AID−/−mice expelledNippostrongylus brasiliensisnormally, they required a much longer period to expelS. venezuelensisthan wild-type (WT) mice. Adoptive transfers of immune sera fromS. venezuelensis-infected but notN. brasiliensis-infected mice restored the ability of AID−/−mice to promptly expelS. venezuelensis. Immune serum-derived IgG and IgE induced worm expulsion via Fc γ receptor III (FcγRIII) and Fc ε receptor I (FcεRI), respectively, and a mixture of IgG and IgE showed collaborative effects. Whereas FcγRIII−/−mice or FcεRIα−/−mice normally could expelS. venezuelensis, FcγRIII−/−mice, when their IgE was neutralized by anti-IgE, or FcεRIα−/−mice, when their IgG binding to FcγRIII was blocked by anti-FcγRIII, showed a markedly reduced ability to expelS. venezuelensis. These data reveal that IgG and IgE play redundant roles but act in concert to accelerateS. venezuelensisexpulsion. Mast cell-deficient mice, even those equipped with immune serum-derived IgG or IgE, failed to expelS. venezuelensispromptly, suggesting that mast cells are cellular targets of IgG and IgE.
Aberration in the palatal root of the maxillary first molar
Authors: Rajalbandi Sandeep , Shingte Sandhya Narayan , Sundaresh K J , Mallikarjuna Rachappa
Published: April 2013

Thorough knowledge of root canal morphology is essential for the endodontic therapy. Variations in the root and root canal morphology, especially in multirooted teeth, are a constant challenge for diagnosis and management. The dentist needs to be familiar with the various root canal configurations and their variations for successful endodontic therapy. There are rare variations in canal number and configuration in maxillary molars, which could affect treatment outcome. Two lingual root structures are occasionally found on human permanent maxillary molars. One of these is the normal lingual root, which is always present, the other is a supernumerary structure which can be located either mesiolingually (radix mesiolingualis) or distolingually (radix distolingualis). The purpose of this paper is to review the literature and to demonstrate a case report which describes the successful non-surgical endodontic management of an unusual maxillary first molar with four separate roots and four canals.
THEORETICAL STUDY OF PHASE FORMING, MAGNETIZATION AND LATTICE VIBRATIONS OF Fe23-xTxB6(T = Cr, Mn, Ni, C), Fe23 C6, Fe23B6 AND Fe23CB6
Authors: WANG XIAO-XU , QIAN PING , AN ZHI-WEI , LI YA-PING , ZHANG ZHEN-FENG , LI JIN-CHUN , CHEN NAN-XIAN
Published: April 2013

We present a theoretical investigation on the phase stability, site preference and lattice constants of Fe 23-x T x B 6( T = Cr , Mn , Ni , C ), Fe 23 C 6 and Fe 23 CB 6. The calculated results show that in Fe 23-x T x B 6 the Cr , Mn or Ni atoms prefer 4a sites. Fe 23 CB 6 may form with Cr 23 C 6 prototype structure, and the carbon atoms are positioned at 4a sites. The calculated lattice constants are found to agree with report in literatures. We have calculated the magnetic moments of Fe 23 C 6, Fe 23 B 6 and Fe 23 CB 6 compounds. Furthermore, the total and partial phonon densities of states are evaluated first for these compounds. The analysis of the inverted potentials explains qualitatively the contributions of different atoms to the vibrational modes.
DIMENSIONAL CROSSOVER AND DIMENSIONAL EFFECTS IN QUASI-TWO-DIMENSIONAL BOSE GASES
Authors: HU YING , LIANG ZHAOXIN
Published: April 2013

This paper gives a systematic review on studies of dimensional effects in pure- and quasi-two-dimensional (2D) Bose gases, focusing on the role of dimensionality in the fundamental relation among the universal behavior of breathing mode, scale invariance and dynamic symmetry. First, we illustrate the emergence of universal breathing mode in the case of pure 2D Bose gases, and elaborate on its connection with the scale invariance of the Hamiltonian and the hidden SO(2, 1) symmetry. Next, we proceed to quasi-2D Bose gases, where excitations are frozen in one direction and the scattering behavior exhibits a 3D to 2D crossover. We show that the original SO(2, 1) symmetry is broken by arbitrarily small 2D effects in scattering, which consequently shifts the breathing mode from the universal frequency. The predicted shift rises significantly from the order of 0.5% to more than 5% in transiting from the 3D-scattering to the 2D-scattering regime. Observing this dimensional effect directly would present an important step in revealing the interplay between dimensionality and quantum fluctuations in quasi-2D.
SYNTHESIS OF LOW-LOSS METAMATERIALS WITH NEGATIVE INDEX IN THE VISIBLE DOMAIN
Authors: GARCÍA-MECA CARLOS
Published: April 2013

Over the last decade, negative index media have attracted much attention due to their potential applications, especially the possibility of constructing superlenses. However, achieving high-performance negative-index metamaterials at visible frequencies, where this kind of media could find many applications, still remains a challenge. In this article, we provide a brief overview of the main routes for the implementation of metamaterials with negative index in this band, with a special focus on the so-called fishnet metamaterial. We pay particular attention to a specific fishnet configuration that recently allowed for the experimental demonstration of a low-loss and polarization-insensitive negative-index band in the visible regime.
AN ADAPTIVE FILTERING ALGORITHM TO COMPENSATE FOR FREQUENCY-DEPENDENT IMAGE INTERFERENCE IN PRACTICAL WIRELESS RECEIVERS
Authors: LIU YING , MIKHAEL WASFY B.
Published: April 2013

Frequency-dependent image interference is an inevitable impairment in wideband quadrature receivers. To suppress this interference, this paper presents a non-data-aided adaptive compensation algorithm, optimal block adaptive filtering algorithm based on circularity (OBA-C). This technique exploits the concept that the image interference in wireless systems causes the received complex signal to lose its nature of circularity. Then the OBA-C algorithm restores the circularity of the signal to compensate for the image interference. To avoid manually selecting a step size, the presented algorithm employs the complex Taylor series expansion to optimally update the adaptive filter coefficients. This technique fully exploits the degrees of freedom of the system, and generates an individual update for each filter coefficient at each iteration. Computer simulations are carried out to test the performance of the OBA-C for practical levels of image interference. The simulation results illustrate that the OBA-C achieves fast convergence and excellent image rejection performance. Other advantages of OBA-C are also analyzed, including the robustness against radio frequency impairments and different levels of image interference.
LOOKBACK OPTION PRICES UNDER A SPECTRALLY NEGATIVE TEMPERED-STABLE MODEL
Authors: COQUERET GUILLAUME
Published: April 2013

We perform a Laplace transform inversion in the time parameter on the two Wiener-Hopf factors for a spectrally negative tempered stable Lévy process. This yields the issuing price of continuously monitored lookback options. We also propose a simulation technique for the purpose of Monte-Carlo valuation and discuss the convergence rate to continuous prices when the number of discretization steps (i.e. monitoring dates) goes to infinity.
Cash Holdings: Determining Factors and Impact on Future Operating Performance for Listed versus Unlisted Firms
Authors: Anagnostopoulou Seraina C.
Published: April 2013

Research suggests that the cash ratios of private firms are lower than the ones of public firms, which is not consistent with an expectation for increased importance of the precautionary motive for firms with fewer funding options. The study provides a significant explanation on these lower ratios, attributed to differences in leverage, capital expenditures, internally generated cash flows, and corporate governance. The study finally testifies that excess cash holdings are positively associated with future operating performance for private, but not public firms, a finding which is interpreted as a manifestation of capital raising constraints for unlisted versus listed firms.
Fricative computing
Authors: Vardi Moshe Y.
Published: April 2013

Let's bring friction back into computing.
Proving grounds
Authors: Wright Alex
Published: April 2013

Researchers are making headway with one of quantum computing's major theoretical problems: multi-prover interactive proofs.
Vanishing electronics
Authors: Greengard Samuel
Published: April 2013

Engineers are reinventing electronics by building safe devices that dissolve in the body or within the environment. The technology could redefine everything from medicine to computing.
Discrimination in online ad delivery
Authors: Sweeney Latanya
Published: April 2013

Google ads, black names and white names, racial discrimination, and click advertising.
Frequent Inactivation of Cysteine Dioxygenase Type 1 Contributes to Survival of Breast Cancer Cells and Resistance to Anthracyclines
Authors: Jeschke Jana , O'Hagan Heather M. , Zhang Wei , Vatapalli Rajita , Calmon Marilia Freitas , Danilova Ludmila , Nelkenbrecher Claudia , Van Neste Leander , Bijsmans Ingrid T.G.W. , Van Engeland Manon , Gabrielson Edward , Schuebel Kornel E. , Winterpacht Andreas , Baylin Stephen B. , Herman James G. , Ahuja Nita
Published: April 2013

Purpose: Genome-wide DNA methylation analyses have identified hundreds of candidate DNA-hypermethylated genes in cancer. Comprehensive functional analyses provide an understanding of the biologic significance of this vast amount of DNA methylation data that may allow the determination of key epigenetic events associated with tumorigenesis.

Experimental Design: To study mechanisms of cysteine dioxygenase type 1 (CDO1) inactivation and its functional significance in breast cancer in a comprehensive manner, we screened for DNA methylation and gene mutations in primary breast cancers and analyzed growth, survival, and reactive oxygen species (ROS) production in breast cancer cells with restored CDO1 function in the context of anthracycline treatment.

Results: DNA methylation-associated silencing of CDO1 in breast cancer is frequent (60%), cancer specific, and correlates with disease progression and outcome. CDO1 function can alternatively be silenced by repressive chromatin, and we describe protein-damaging missense mutations in 7% of tumors without DNA methylation. Restoration of CDO1 function in breast cancer cells increases levels of ROS and leads to reduced viability and growth, as well as sensitization to anthracycline treatment. Priming with 5-azacytidine of breast cancer cells with epigenetically silenced CDO1 resulted in restored expression and increased sensitivity to anthracyclines.

Conclusion: We report that silencing of CDO1 is a critical epigenetic event that contributes to the survival of oxidative-stressed breast cancer cells through increased detoxification of ROS and thus leads to the resistance to ROS-generating chemotherapeutics including anthracyclines. Our study shows the importance of CDO1 inactivation in breast cancer and its clinical potential as a biomarker and therapeutic target to overcome resistance to anthracyclines. Clin Cancer Res; 19(12); 3201–11. ©2013 AACR.
Attentional Bias for Alcohol-Related Stimuli among Belief Based and Non-Belief Based Non-Drinkers
Authors: Moss A.C. , Albery I.P. , Siddiqui I. , Rycroft N.
Published: April 2013

Background/Aims: Research has provided evidence for an association between attentional biases for substance-related stimuli and the development and maintenance of a variety of addictive behaviours. Attempts at reducing attentional bias amongst harmful and dependent drinkers have provided evidence to suggest that reduced attentional bias in heavy drinkers would lead to necessary reductions in alcohol intake. We tested one aspect of this assumption by measuring attentional bias amongst non-drinkers who, if the link between attentional bias and actual drug use is causal, should demonstrate no attentional bias for alcohol-related stimuli. Methods: An alcohol Stroop task was administered to belief-based abstainers, non-belief based abstainers and light social drinkers to measure attentional biases for alcohol-related words compared to neutral words. Results: Belief-based abstainers demonstrated significant attentional bias for alcohol-related stimuli, whilst non-belief based abstainers and light social drinkers did not. Conclusion: Attentional biases towards alcohol-related stimuli are not specific to harmful and problem drinkers, which has implications for interventions based on attentional bias change.
Effects of Losartan and Pentoxifylline on Renal Dimethylarginine Dimethylaminohydrolase-1 Expression in Proteinuric Nephropathy
Authors: Park Sun-Hee , Hyun Seung Hyea , Ryu Hye-Myung , Ahn Ji-Sun , Oh Se-Hyun , Oh Eun-Joo , Yoon Se-Hee , Choi Ji-Young , Cho Jang-Hee , Kim Chan-Duck , Kim Yong-Lim
Published: April 2013

Background/Aims: Circulatory asymmetric dimethylarginine (ADMA) is correlated with proteinuria and endothelial dysfunction in patients with proteinuric renal diseases. However, it is not known whether proteinuria itself affects expression of dimethylarginine dimethylaminohydrolase (DDAH), a degrading enzyme of ADMA, in kidney. The aim of this study is to evaluate the direct effects of losartan and/or pentoxifylline on expression of renal DDAH-1 and its relation to oxidative stress in the setting of albuminuria. Methods: Using NRK52E cells, DDAH-1 mRNA and protein were determined after exposure to albumin with losartan and/or pentoxifylline. Reactive oxygen species (ROS), PKC activity, and NOX-4 mRNA were also measured. In addition, the effect of losartan and/or pentoxifylline on renal expression of DDAH-1 and serum ADMA were evaluated in a rat model of proteinuric nephropathy. Results: Exposure to albumin resulted in increased release of N-acetyl-β-D-glucosaminidase along with an increase of TNF-α, 8-hydroxy-2′-deoxyguanosine, and angiotensin II in NRK52E cells. Losartan and pentoxifylline reversed albumin-induced decrease of DDAH-1 mRNA and protein expression and DDAH-1 activity. The effects of losartan and pentoxifylline on DDAH-1 mRNA were associated with reduction of ROS. In addition, treatment with losartan and pentoxifylline resulted in an attenuated change of renal DDAH-1 protein expression and serum ADMA levels in vivo. Conclusion: DDAH-1 was positively regulated by losartan and pentoxifylline with its antioxidative effect in albumin-exposed renal proximal tubular cells. Combined treatment with losartan and pentoxifylline has a direct beneficial effect on expression of renal DDAH-1, and, thus, at least in part, modulates the circulatory levels of ADMA in proteinuric nephropathy.
The Association of Prevalent Kidney Stone Disease with Mortality in US Adults: The National Health and Nutrition Examination Survey III, 1988-1994
Authors: Tang Jie , Mettler Pam , McFann Kim , Chonchol Michel
Published: April 2013

Background: Kidney stone disease is associated with hypertension, diabetes, metabolic syndrome, kidney function decline, and increased cardiovascular (CV) events. However, its association with all-cause and CV mortality is unclear. Methods: We used the Third National Health and Nutrition Examination Survey, a large US population-based study with mortality data through 2006 determined via linkage to the National Death Index to examine kidney stone disease in relation to all-cause and CV mortality risks. Results: Among 14,879 men and women over 18 years of age who were eligible for analysis, 683 participants reported a history of kidney stones. There was a total of 3,590 all-cause and 1,608 CV deaths during a median follow-up of 14.9 years. Stone formers had a significantly higher risk for all-cause mortality [hazard ratio (HR): 1.95, 95% CI: 1.64-2.33, p < 0.0001) and CV mortality (HR: 2.05, 95% CI: 1.60-2.62, p < 0.0001) in unadjusted analyses. However, after multivariate adjustment for age, gender, race, and poverty, stone formers no longer had increased risk for all-cause mortality (HR: 1.08, 95% CI: 0.93-1.26, p = 0.3) and CV mortality (HR: 1.07, 95% CI: 0.84-1.36, p = 0.6). Results remain unchanged after further adjustment for other clinical variables including history of hypertension, diabetes, and CV disease. Conclusion: The increased risk of all-cause and CV mortality in kidney stone formers is likely a reflection of unique demographics and associated comorbidities. There is no independent association of prevalent kidney stone disease with all-cause and CV mortality.
Hidden in the dry woods: Mapping the collection history and distribution of Gymnanthes boticario, a well-collected but very recently described species restricted to the dry vegetation of South America
Authors: DE OLIVEIRA LUCIANA DOS SANTOS D. , MORO MARCELO FREIRE , LUGHADHA EIMEAR M. NIC , MARTINS FERNANDO ROBERTO , DE MELO ANDRÉ LAURÊNIO , ESSER HANS-JOACHIM , SALES MARGARETH F.
Published: April 2013

Botanists estimate that 80 to 90% of existing plant species have already been described and it is expected that most undescribed species are rare or narrow endemic ones. Here we map the geographical distribution of Gymnanthes boticario, a species described in 2010, and show that the species is not only widespread, but was well-collected in the Caatinga semiarid vegetation prior to its description. During a revision of the genus Gymnanthes we also found collections of G. boticario in the Brazilian Mato Grosso do Sul state (in Pantanal ecoregion), in Paraguay (in Cerro Léon dry forests) and in Bolivia (in Chiquitano dry forest ecoregion) in a pattern that closely resembles the Pleistocenic Arc Hypothesis. We map the continental distribution of G. boticario, report the first records of it for Bolivia, Paraguay and the Brazilian Pantanal and show the rich data available in herbaria for a plant only recently described.
L’osservatore e l’oggetto osservato: I cavalletti di Remo Salvadori
Authors: Carrera Alessandro
Published: April 2013

Viene qui esaminata la relazione tra l'osservatore e l'oggetto osservato prendendo come spunto gli osservatori progetttati e costruiti a partire dal 1981 dall'artista italiano Remo Salvadori. L'11 gennaio del 1951 tre filosofi (Alfred Jules Ayer, Georges Bataille, e Maurice Merleau-Ponty) e un fisico (Georges Ambrosino) ebbero una lunga conversazione in un bistrot parigino. L'argomento era se il sole fosse esistito prima che gli esseri umani riconoscessero la sua esistenza e lo chiamassero “sole”. Per Ayer non c'erano dubbi: poiché la veritá é indipendente dal tempo, il “sole” c'era sempre stato. L'oggetto si sposta nel tempo; non così l'osservatore (la verità). Bataille, Merleau-Ponty, e Ambrosino si dichiararono in disaccordo con Ayer: se non c'è un osservatore, non c'è nemmeno un oggetto osservato. Quasiasi “cosa” fosse il prima che gli uomini gli dessero quel nome, certamente non era il “sole”. Il linguaggio e il mondo non possono essere separati. Costruiti con la forma di un treppiede senza la macchina fotografica, gli “osservatori” di Salvadori sono la rappresentazione perfetta, e allo stesso tempo una critica sottile, dello sguardo astrattizzante e concettualizzante che “vede” la verità dell'oggetto anche senza vedere l'oggetto attuale e contingente.
Writing Campanian lives: Considerations of transnational identity and belonging
Authors: Glenn Diana
Published: April 2013

Australia experienced a period of mass migration from Italy in the immediate post-Second World War period. This article presents findings from the oral narratives of a cohort of first-generation Italians who migrated from the region of Campania, in southern Italy, to the city of Adelaide, in the state of South Australia, in the 1950s and 1960s. In the course of exploring the pre- and post-migratory vicissitudes of the informants, as well as their personal memories of the long sea voyage, the analysis examines the effects of cultural dislocation over a broad arc of time and discusses issues connected to identity formation, belonging, the loss of home and cultural maintenance on a group of migrants who are now senior citizens. The oral testimonies evidence the candid reactions of the project informants to the prospect of transnational migration, the cultural impact upon reaching the unfamiliar destination site and the transformative factors that motivated both the maintenance of core values and the enactment of cross-cultural communication strategies. The oral testimonies reveal the project conversants’ negotiation of cultural boundaries, in order to cope with the assimilation pressures being exerted by the dominant culture, and their honing of survival strategies in order to facilitate the identity formation and successful integration of subsequent generations. The article also includes excerpts from the oral testimonies of a second cohort of informants of Anglo-British origin who were residing in Adelaide during the post-war period.
Dante, egocentrico e/o profeta?
Authors: Santagata Marco
Published: April 2013

In più luoghi della Commedia Dante si attribuisce il ruolo di profeta, che gli potrebbe derivare da motivi di ordine psicologico, sociale ed economico, in grado di causare senso di insicurezza e quindi di rivalsa. La madre, Beatrice, gli amici facevano tutti parte di un ceto sociale e finanziario diverso dal suo e questo potrebbe aver generato in uno spirito di per sé ambizioso meccanismi di frustrazione, di competizione e di eccessiva autostima. Parla sovente di sé e perfino delle sue malattie: racconta della perdita della vista e della coscienza all’apparire della donna amata. I modi in cui si manifestano queste crisi fanno pensare ad attacchi apoplettici o epilettici, poi trasferiti nella finzione poetica in episodi come quello di Vanni nel canto XXIV dell’ Inferno. Dante, inoltre, si attribuisce spirito profetico. Nel canto XIX dell’ Inferno inveisce contro la corruzione dilagante della Chiesa, caricando di valore figurale un episodio occorsogli da giovane, analogo all’atto di Geremia che ruppe un’anfora sotto le mura di Gerusalemme. Ulteriore prova della sua coscienza profetica è la risposta a Giovanni del Virgilio, in cui manifesta la certezza di ricevere l’alloro grazie alla Commedia. Dove? Nel suo San Giovanni, dove indosserà il pileus, il cappello portato da coloro che sono banditi dalla città.
The Strength of Sibling Ties: Sibling Influence on Status Attainment in a Chinese Family
Authors: Zhang Qian Forrest
Published: April 2013

What allowed eight siblings from a politically disadvantaged rural family to overcome institutional barriers and achieve upward mobility during Maoist China? What then restricted their children’s chances of upward mobility during the Reform era, when both family background and institutional environment were more favourable? In studying this anomalous case, whose experiences contradicted the well-documented effects of state policies and yet cannot be explained by parental influence, this study examines how adult siblings influenced each other’s status attainment processes, an issue largely neglected in the literature. Through comparing the micro-level mobility processes of the two generations in this family, I propose that, in times of rapid social change, sibling influence is more effective in generating status gain than parental influence, because the extensivity of sibling ties allows people to mobilize more relevant and heterogeneous social resources to facilitate social mobility.