Publications by authors named "Daniel Ott"

28 Publications

  • Page 1 of 1

Curved-crease origami face shields for infection control.

PLoS One 2021 8;16(2):e0245737. Epub 2021 Feb 8.

Centre for Natural Material Innovation, Department of Architecture, University of Cambridge, Cambridge, United Kingdom.

The COVID-19 pandemic has created enormous global demand for personal protective equipment (PPE). Face shields are an important component of PPE for front-line workers in the context of the COVID-19 pandemic, providing protection of the face from splashes and sprays of virus-containing fluids. Existing face shield designs and manufacturing procedures may not allow for production and distribution of face shields in sufficient volume to meet global demand, particularly in Low and Middle-Income countries. This paper presents a simple, fast, and cost-effective curved-crease origami technique for transforming flat sheets of flexible plastic material into face shields for infection control. It is further shown that the design could be produced using a variety of manufacturing methods, ranging from manual techniques to high-volume die-cutting and creasing. This demonstrates the potential for the design to be applied in a variety of contexts depending on available materials, manufacturing capabilities and labour. An easily implemented and flexible physical-digital parametric design methodology for rapidly exploring and refining variations on the design is presented, potentially allowing others to adapt the design to accommodate a wide range of ergonomic and protection requirements.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0245737PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7869980PMC
February 2021

Accuracy of the end-expiratory lung volume measured by the modified nitrogen washout/washin technique: a bench study.

J Transl Med 2021 01 19;19(1):36. Epub 2021 Jan 19.

Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.

Background: The functional residual capacity (FRC) determines the oxygenating capacity of the lung and is heavily affected in the clinical context of the acute respiratory distress syndrome. Nitrogen-wash-in/wash-out methods have been used to measure FRC. These methods have rarely been validated against exactly known volumes. The aim of the study was to assess the accuracy and precision of the N washout/washin method in measuring FRC, by comparing it with set volumes in a lung simulator.

Methods: We conducted a diagnostic bench study in the Intensive Care Unit and Radiology Department of a tertiary hospital in Switzerland. Using a fully controllable high fidelity lung simulator (TestChest®), we set the functional residual capacity at 1500 ml, 2000 ml and 2500 ml and connected to the GE Carestation respirator, which includes the nitrogen washout/washin technique (INview™ tool). FRC was then set to vary by different levels of PEEP (5, 8, 12 and 15 cmHO). The main outcome measures were bias and precision of the TestChest® when compared to the results from the washout/washin technique, according to the results of a Bland Altman Analysis. We verified our findings with volumetric computed tomography.

Results: One hundred and thirty-five nitrogen-wash-in/wash-out measurements were taken at three levels of FO (0.4, 0.5, 0.6). The CT volumetry reproduced the set end-expiratory volumes at the Simulator with a bias of 4 ml. The nitrogen-wash-in/wash-out method had a bias of 603 ml with acceptable limits of agreement (95% CI 252 to - 953 ml). Changes were detected with a concordance rate of 97%.

Conclusions: We conclude that the TestChest® simulator is an accurate simulation tool, concerning the simulation of lung volumes. The nitrogen wash-in/wash out method correlated positively with FRC changes, despite a relatively large bias in absolute measurements. The reference volumes in the lung simulator verified with CT volumetry were very close to their expected values. The reason for the bias could not be determined.
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http://dx.doi.org/10.1186/s12967-021-02703-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7815189PMC
January 2021

Interspecific variation in spruce constitutive and induced defenses in response to a bark beetle fungal symbiont provides insight into traits associated with resistance.

Tree Physiol 2021 Jan 15. Epub 2021 Jan 15.

USDA-Forest Service, Rocky Mountain Research Station, Fort Collins, CO 80526-2098.

Differences in defensive traits of tree species may predict why some conifers are susceptible to bark beetle-fungal complexes and others are not. A symbiotic fungus (Leptographium abietinum) associated with the tree-killing bark beetle (Dendroctonus rufipennis) is phytopathogenic to host trees and may hasten tree decline during colonization by beetles, but defense responses of mature trees to the fungus have not been experimentally examined. To test the hypothesis that interspecific variation in spruce resistance is explained by defense traits we compared constitutive (bark thickness and constitutive resin ducts) and induced defenses (resin flow, monoterpene composition, concentration, phloem lesion formation, and traumatic resin ducts) between two sympatric spruces: Engelmann spruce (Picea engelmannii, a susceptible host) and blue spruce (P. pungens, a resistant host) in response to fungal inoculation. Four central findings emerged: (1) blue spruce has thicker outer bark and thinner phloem than Engelmann spruce, which may restrict fungal access to phloem and result in less beetle-available resource overall; (2) both spruce species induce monoterpenes in response to inoculation but blue spruce has higher constitutive monoterpene levels, induces monoterpenes more rapidly, and induces higher concentrations over a period of time consistent with spruce beetle attack duration; (3) Engelmann and blue spruce differed in the monoterpenes they upregulated in response to fungal inoculation: blue spruce upregulated α-pinene, terpinolene, and γ-terpinene, but Engelmann spruce upregulated 3-carene and linalool; and (4) blue spruce has a higher frequency of constitutive resin ducts and produces more traumatic resin ducts in annual growth increments than Engelmann spruce, though Engelmann spruce produces more resin following aseptic wounding or fungal inoculation. These findings suggest that higher constitutive resin duct densities and monoterpene concentrations, as well as the ability to rapidly induce specific monoterpenes in response to L. abietinum inoculation, are phenotypic traits associated with hosts resistant to spruce beetle colonization.
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http://dx.doi.org/10.1093/treephys/tpaa170DOI Listing
January 2021

Interspecific variation in spruce constitutive and induced defenses in response to a bark beetle fungal symbiont provides insight into traits associated with resistance.

Tree Physiol 2021 Jan 15. Epub 2021 Jan 15.

USDA-Forest Service, Rocky Mountain Research Station, Fort Collins, CO 80526-2098.

Differences in defensive traits of tree species may predict why some conifers are susceptible to bark beetle-fungal complexes and others are not. A symbiotic fungus (Leptographium abietinum) associated with the tree-killing bark beetle (Dendroctonus rufipennis) is phytopathogenic to host trees and may hasten tree decline during colonization by beetles, but defense responses of mature trees to the fungus have not been experimentally examined. To test the hypothesis that interspecific variation in spruce resistance is explained by defense traits we compared constitutive (bark thickness and constitutive resin ducts) and induced defenses (resin flow, monoterpene composition, concentration, phloem lesion formation, and traumatic resin ducts) between two sympatric spruces: Engelmann spruce (Picea engelmannii, a susceptible host) and blue spruce (P. pungens, a resistant host) in response to fungal inoculation. Four central findings emerged: (1) blue spruce has thicker outer bark and thinner phloem than Engelmann spruce, which may restrict fungal access to phloem and result in less beetle-available resource overall; (2) both spruce species induce monoterpenes in response to inoculation but blue spruce has higher constitutive monoterpene levels, induces monoterpenes more rapidly, and induces higher concentrations over a period of time consistent with spruce beetle attack duration; (3) Engelmann and blue spruce differed in the monoterpenes they upregulated in response to fungal inoculation: blue spruce upregulated α-pinene, terpinolene, and γ-terpinene, but Engelmann spruce upregulated 3-carene and linalool; and (4) blue spruce has a higher frequency of constitutive resin ducts and produces more traumatic resin ducts in annual growth increments than Engelmann spruce, though Engelmann spruce produces more resin following aseptic wounding or fungal inoculation. These findings suggest that higher constitutive resin duct densities and monoterpene concentrations, as well as the ability to rapidly induce specific monoterpenes in response to L. abietinum inoculation, are phenotypic traits associated with hosts resistant to spruce beetle colonization.
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http://dx.doi.org/10.1093/treephys/tpaa170DOI Listing
January 2021

spp. nosocomial outbreak assessment using rapid MALDI-TOF MS based typing, confirmed by whole genome sequencing.

Antimicrob Resist Infect Control 2019 4;8:171. Epub 2019 Nov 4.

Department of Infectious Diseases, Bern University Hospital, University of Bern, Freiburgstrasse, 3001 Bern, Switzerland.

Background: A number of episodes of nosocomial spp bacteremia (two cases per year) were observed at Bern University Hospital, Switzerland, from 2015 to 2017. This triggered an outbreak investigation.

Methods: Cases of spp bacteremias that occurred between August 2011 and February 2017 were investigated employing line lists, environmental sampling, rapid protein- (MALDI-TOF MS), and genome-based typing (pulsed field gel electrophoresis and whole genome sequencing) of the clinical isolates.

Results: We describe a total of eight bacteremia episodes due to ( = 2), genomovar G3 ( = 5) and ( = 1). Two tight clusters were observed by WGS typing, representing the two isolates (cluster I, isolated in 2015) and four of the genomovar G3 isolates (cluster II, isolated in 2016 and 2017), suggesting two different point sources. The epidemiological investigations revealed two computer tomography (CT) rooms as common patient locations, which correlated with the two outbreak clusters. MALDI-TOF MS permitted faster evaluation of strain relatedness than DNA-based methods. High resolution WGS-based typing confirmed the MALDI-TOF MS clustering.

Conclusions: We report clinical and epidemiological characteristics of two outbreak clusters with spp. bacteremia likely acquired during CT contrast medium injection and highlight the use of MALDI-TOF MS as a rapid tool to assess relatedness of rare gram-negative pathogens in an outbreak investigation.
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http://dx.doi.org/10.1186/s13756-019-0619-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6829841PMC
July 2020

Enteritis necroticans - megacolon with massive portal venous gas embolization in a patient after malabsorptive bariatric surgery.

Anaesthesiol Intensive Ther 2019 ;51(4):333-334

Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.

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http://dx.doi.org/10.5114/ait.2019.88573DOI Listing
August 2020

Estimating error rates for firearm evidence identifications in forensic science.

Forensic Sci Int 2018 Mar 13;284:15-32. Epub 2017 Dec 13.

Statistical Engineering Division, National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899, USA.

Estimating error rates for firearm evidence identification is a fundamental challenge in forensic science. This paper describes the recently developed congruent matching cells (CMC) method for image comparisons, its application to firearm evidence identification, and its usage and initial tests for error rate estimation. The CMC method divides compared topography images into correlation cells. Four identification parameters are defined for quantifying both the topography similarity of the correlated cell pairs and the pattern congruency of the registered cell locations. A declared match requires a significant number of CMCs, i.e., cell pairs that meet all similarity and congruency requirements. Initial testing on breech face impressions of a set of 40 cartridge cases fired with consecutively manufactured pistol slides showed wide separation between the distributions of CMC numbers observed for known matching and known non-matching image pairs. Another test on 95 cartridge cases from a different set of slides manufactured by the same process also yielded widely separated distributions. The test results were used to develop two statistical models for the probability mass function of CMC correlation scores. The models were applied to develop a framework for estimating cumulative false positive and false negative error rates and individual error rates of declared matches and non-matches for this population of breech face impressions. The prospect for applying the models to large populations and realistic case work is also discussed. The CMC method can provide a statistical foundation for estimating error rates in firearm evidence identifications, thus emulating methods used for forensic identification of DNA evidence.
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http://dx.doi.org/10.1016/j.forsciint.2017.12.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5961495PMC
March 2018

Cardiopulmonary resuscitation and intrathoracic renal ectopy.

Intensive Care Med 2018 Mar 8;44(3):378-379. Epub 2017 Nov 8.

Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, 3010, Bern, Switzerland.

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http://dx.doi.org/10.1007/s00134-017-4987-6DOI Listing
March 2018

Applying 3D measurements and computer matching algorithms to two firearm examination proficiency tests.

Forensic Sci Int 2017 Feb 21;271:98-106. Epub 2016 Dec 21.

National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA. Electronic address:

In order for a crime laboratory to assess a firearms examiner's training, skills, experience, and aptitude, it is necessary for the examiner to participate in proficiency testing. As computer algorithms for comparisons of pattern evidence become more prevalent, it is of interest to test algorithm performance as well, using these same proficiency examinations. This article demonstrates the use of the Congruent Matching Cell (CMC) algorithm to compare 3D topography measurements of breech face impressions and firing pin impressions from a previously distributed firearms proficiency test. In addition, the algorithm is used to analyze the distribution of many comparisons from a collection of cartridge cases used to construct another recent set of proficiency tests. These results are provided along with visualizations that help to relate the features used in optical comparisons by examiners to the features used by computer comparison algorithms.
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http://dx.doi.org/10.1016/j.forsciint.2016.12.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5412512PMC
February 2017

A Novel Analog Reasoning Paradigm: New Insights in Intellectually Disabled Patients.

PLoS One 2016 26;11(2):e0149717. Epub 2016 Feb 26.

Centre de Référence, Déficiences Intellectuelles de Causes Rares, Hôpital Femme Mère Enfant, Hospices Civils de Lyon, Bron, France.

Background: Intellectual Disability (ID) is characterized by deficits in intellectual functions such as reasoning, problem-solving, planning, abstract thinking, judgment, and learning. As new avenues are emerging for treatment of genetically determined ID (such as Down's syndrome or Fragile X syndrome), it is necessary to identify objective reliable and sensitive outcome measures for use in clinical trials.

Objective: We developed a novel visual analogical reasoning paradigm, inspired by the Progressive Raven's Matrices, but appropriate for Intellectually Disabled patients. This new paradigm assesses reasoning and inhibition abilities in ID patients.

Methods: We performed behavioural analyses for this task (with a reaction time and error rate analysis, Study 1) in 96 healthy controls (adults and typically developed children older than 4) and 41 genetically determined ID patients (Fragile X syndrome, Down syndrome and ARX mutated patients). In order to establish and quantify the cognitive strategies used to solve the task, we also performed an eye-tracking analysis (Study 2).

Results: Down syndrome, ARX and Fragile X patients were significantly slower and made significantly more errors than chronological age-matched healthy controls. The effect of inhibition on error rate was greater than the matrix complexity effect in ID patients, opposite to findings in adult healthy controls. Interestingly, ID patients were more impaired by inhibition than mental age-matched healthy controls, but not by the matrix complexity. Eye-tracking analysis made it possible to identify the strategy used by the participants to solve the task. Adult healthy controls used a matrix-based strategy, whereas ID patients used a response-based strategy. Furthermore, etiologic-specific reasoning differences were evidenced between ID patients groups.

Conclusion: We suggest that this paradigm, appropriate for ID patients and developmental populations as well as adult healthy controls, provides an objective and quantitative assessment of visual analogical reasoning and cognitive inhibition, enabling testing for the effect of pharmacological or behavioural intervention in these specific populations.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0149717PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4771701PMC
July 2016

Risk factors for fatal outcome in surgical patients with postoperative aspiration pneumonia.

Int J Surg 2016 Mar 20;27:21-25. Epub 2016 Jan 20.

Department of Visceral Surgery and Medicine, Bern University Hospital, Bern, Switzerland. Electronic address:

Introduction: Aspiration pneumonia in hospitalized surgical patients has been associated with a mortality of approximately 30%. The aim of this study was to assess pre-, intra- and postoperative risk factors for mortality in patients suffering aspiration pneumonia after abdominal surgery.

Methods: Retrospective study from 01/2006-12/2012 of patients with clinically and radiologically confirmed aspiration pneumonia after abdominal surgery.

Results: A total of 70 patients undergoing abdominal surgery and postoperative aspiration pneumonia were identified. There were 53 (76%) male patients, the mean age was 71 ± 12 years and the mean ASA score was 3 ± 1. The surgical procedures included 32 colorectal or small bowel resections, 10 partial liver resections, 9 gastric surgeries, 8 esophageal resections, 5 pancreatic surgeries, and 6 hernia repairs. Aspiration pneumonia occurred at mean postoperative day 7 ± 10. Overall, 53% (n = 37) of patients required re-intubation, with 4 ± 5 days of additional mechanical ventilation. Mean hospital and ICU length of stay was 32 ± 25 days and 6 ± 9 days, respectively. Overall mortality was 27% (n = 19). Forward logistic regression revealed older age [OR 7.41 (95% CI: 1.29-42.62)], bilateral aspiration pneumonia [OR 7.39 (95% CI: 1.86-29.29)] and intraoperative requirement of blood component transfusion [OR 5.09 (95% CI: 1.34-19.38)] as independent risk factors for mortality (overall R(2) = 0.336).

Conclusion: Postoperative aspiration pneumonia remains a severe complication with significant mortality. Increasing age, the need for intraoperative blood component transfusion and bilateral pulmonary infiltrates are independent risk factors for fatal outcome after aspiration pneumonia. Therefore, these patients suffering aspiration pneumonia require special attention and increased monitoring.
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http://dx.doi.org/10.1016/j.ijsu.2016.01.043DOI Listing
March 2016

Death after Sexual Intercourse.

Case Rep Emerg Med 2015 1;2015:646438. Epub 2015 Dec 1.

Department of Emergency Medicine, Inselspital, University Hospital Bern, Freiburgstrasse 10, 3010 Bern, Switzerland ; Department of General Anesthesiology, Intensive Care and Pain Management, Medical University of Vienna, Waehringerguertel 18-22, 1090 Vienna, Austria.

Sexuality is an essential aspect of quality of life. Nevertheless, sexual intercourse is physically challenging and leads to distinct changes in blood pressure, heart, and respiratory rate that may lead to vital complications. We present a case report of a 22-year-old female suffering from subarachnoid hemorrhage after sexual intercourse. The patient was immediately transported to hospital by emergency medical services and, after diagnosis, transferred to a tertiary hospital with neurosurgical expertise but died within 24 hours. After postcoital headaches, subarachnoid hemorrhage is the second most common cause of neurological complications of sexual intercourse and therefore patients admitted to an emergency department with headache after sexual intercourse should always be carefully evaluated by cerebral imaging.
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http://dx.doi.org/10.1155/2015/646438DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4678062PMC
December 2015

Hepatocellular Carcinoma Screening With Computed Tomography Using the Arterial Enhancement Fraction With Radiologic-Pathologic Correlation.

Invest Radiol 2016 Jan;51(1):25-32

From the *Department of Diagnostic, Interventional and Pediatric Radiology, University Hospital Inselspital Bern, Bern, Switzerland; †Department of Polyvalent and Oncologic Radiology, University Hospital Pitié-Salpêtrière, Paris, France; ‡Department of Radiology, Duke University Medical Center, Durham, North Carolina; and §Institute of Pathology, University of Bern, Bern, Switzerland.

Objective: The aim of this study was to investigate the performance of the arterial enhancement fraction (AEF) in multiphasic computed tomography (CT) acquisitions to detect hepatocellular carcinoma (HCC) in liver transplant recipients in correlation with the pathologic analysis of the corresponding liver explants.

Materials And Methods: Fifty-five transplant recipients were analyzed: 35 patients with 108 histologically proven HCC lesions and 20 patients with end-stage liver disease without HCC. Six radiologists looked at the triphasic CT acquisitions with the AEF maps in a first readout. For the second readout without the AEF maps, 3 radiologists analyzed triphasic CT acquisitions (group 1), whereas the other 3 readers had 4 contrast acquisitions available (group 2). A jackknife free-response reader receiver operating characteristic analysis was used to compare the readout performance of the readers. Receiver operating characteristic analysis was used to determine the optimal cutoff value of the AEF.

Results: The figure of merit (θ = 0.6935) for the conventional triphasic readout was significantly inferior compared with the triphasic readout with additional use of the AEF (θ = 0.7478, P < 0.0001) in group 1. There was no significant difference between the fourphasic conventional readout (θ = 0.7569) and the triphasic readout (θ = 0.7615, P = 0.7541) with the AEF in group 2. Without the AEF, HCC lesions were detected with a sensitivity of 30.7% (95% confidence interval [CI], 25.5%-36.4%) and a specificity of 97.1% (96.0%-98.0%) by group 1 looking at 3 CT acquisition phases and with a sensitivity of 42.1% (36.2%-48.1%) and a specificity of 97.5% (96.4%-98.3%) in group 2 looking at 4 CT acquisition phases. Using the AEF maps, both groups looking at the same 3 acquisition phases, the sensitivity was 47.7% (95% CI, 41.9%-53.5%) with a specificity of 97.4% (96.4%-98.3%) in group 1 and 49.8% (95% CI, 43.9%-55.8%)/97.6% (96.6%-98.4%) in group 2. The optimal cutoff for the AEF was 50%.

Conclusion: The AEF is a helpful tool to screen for HCC with CT. The use of the AEF maps may significantly improve HCC detection, which allows omitting the fourth CT acquisition phase and thus making a 25% reduction of radiation dose possible.
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http://dx.doi.org/10.1097/RLI.0000000000000201DOI Listing
January 2016

High-contrast filtering by multipass diffraction between paired volume Bragg gratings.

Appl Opt 2015 Nov;54(31):9065-70

High-contrast filtering via multiple reflections between matched volume Bragg gratings (VBGs) is demonstrated. The use of multiple reflections serves to increase the suppression ratio of the out-of-band spectral content such that contributions of grating sidelobes can be mitigated. The result is a device that retains spectral and angular selectivity and diffracts light into a single order with high efficiency but reshapes the spectral/angular response to achieve higher signal-to-noise ratios. We demonstrate that multipass spectral filters can be recorded with extremely high suppression ratios using reflecting Bragg gratings (RBGs) in three different configurations. These filters demonstrate roll-offs of over 150 dB/nm. Similarly, we demonstrate angular filtering by multipass transmitting gratings.
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http://dx.doi.org/10.1364/AO.54.009065DOI Listing
November 2015

Lung nodule detection by microdose CT versus chest radiography (standard and dual-energy subtracted).

AJR Am J Roentgenol 2015 Apr;204(4):727-35

1 Department of Diagnostic, Interventional and Pediatric Radiology, Hospital and University of Bern Inselspital, Freiburgstrasse 10, Bern CH-3010, Switzerland.

Objective: The purpose of this study was to investigate the feasibility of microdose CT using a comparable dose as for conventional chest radiographs in two planes including dual-energy subtraction for lung nodule assessment.

Materials And Methods: We investigated 65 chest phantoms with 141 lung nodules, using an anthropomorphic chest phantom with artificial lung nodules. Microdose CT parameters were 80 kV and 6 mAs, with pitch of 2.2. Iterative reconstruction algorithms and an integrated circuit detector system (Stellar, Siemens Healthcare) were applied for maximum dose reduction. Maximum intensity projections (MIPs) were reconstructed. Chest radiographs were acquired in two projections with bone suppression. Four blinded radiologists interpreted the images in random order.

Results: A soft-tissue CT kernel (I30f) delivered better sensitivities in a pilot study than a hard kernel (I70f), with respective mean (SD) sensitivities of 91.1%±2.2% versus 85.6%±5.6% (p=0.041). Nodule size was measured accurately for all kernels. Mean clustered nodule sensitivity with chest radiography was 45.7%±8.1% (with bone suppression, 46.1%±8%; p=0.94); for microdose CT, nodule sensitivity was 83.6%±9% without MIP (with additional MIP, 92.5%±6%; p<10(-3)). Individual sensitivities of microdose CT for readers 1, 2, 3, and 4 were 84.3%, 90.7%, 68.6%, and 45.0%, respectively. Sensitivities with chest radiography for readers 1, 2, 3, and 4 were 42.9%, 58.6%, 36.4%, and 90.7%, respectively. In the per-phantom analysis, respective sensitivities of microdose CT versus chest radiography were 96.2% and 75% (p<10(-6)). The effective dose for chest radiography including dual-energy subtraction was 0.242 mSv; for microdose CT, the applied dose was 0.1323 mSv.

Conclusion: Microdose CT is better than the combination of chest radiography and dual-energy subtraction for the detection of solid nodules between 5 and 12 mm at a lower dose level of 0.13 mSv. Soft-tissue kernels allow better sensitivities. These preliminary results indicate that microdose CT has the potential to replace conventional chest radiography for lung nodule detection.
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http://dx.doi.org/10.2214/AJR.14.12921DOI Listing
April 2015

A Simple and Fast Spline Filtering Algorithm for Surface Metrology.

J Res Natl Inst Stand Technol 2015 15;120:129-37. Epub 2015 Jul 15.

National Institute of Standards and Technology, Gaithersburg, MD 20899 USA.

Spline filters and their corresponding robust filters are commonly used filters recommended in ISO (the International Organization for Standardization) standards for surface evaluation. Generally, these linear and non-linear spline filters, composed of symmetric, positive-definite matrices, are solved in an iterative fashion based on a Cholesky decomposition. They have been demonstrated to be relatively efficient, but complicated and inconvenient to implement. A new spline-filter algorithm is proposed by means of the discrete cosine transform or the discrete Fourier transform. The algorithm is conceptually simple and very convenient to implement.
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http://dx.doi.org/10.6028/jres.120.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4730687PMC
March 2016

Moiré volume Bragg grating filter with tunable bandwidth.

Opt Express 2014 Aug;22(17):20375-86

We propose a monolithic large-aperture narrowband optical filter based on a moiré volume Bragg grating formed by two sequentially recorded gratings with slightly different resonant wavelengths. Such recording creates a spatial modulation of refractive index with a slowly varying sinusoidal envelope. By cutting a specimen at a small angle, to a thickness of one-period of this envelope, the longitudinal envelope profile will shift from a sine profile to a cosine profile across the face of the device. The transmission peak of the filter has a tunable bandwidth while remaining at a fixed resonant wavelength by a transversal shift of incidence position. Analytical expressions for the tunable bandwidth of such a filter are calculated and experimental data from a filter operating at 1064 nm with bandwidth range 30-90 pm is demonstrated.
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http://dx.doi.org/10.1364/OE.22.020375DOI Listing
August 2014

Acupuncture modulates cortical thickness and functional connectivity in knee osteoarthritis patients.

Sci Rep 2014 Sep 26;4:6482. Epub 2014 Sep 26.

Department of Psychiatry, Massachusetts General Hospital, Charlestown, MA, USA.

In this study, we investigated cortical thickness and functional connectivity across longitudinal acupuncture treatments in patients with knee osteoarthritis (OA). Over a period of four weeks (six treatments), we collected resting state functional magnetic resonance imaging (fMRI) scans from 30 patients before their first, third and sixth treatments. Clinical outcome showed a significantly greater Knee Injury and Osteoarthritis Outcome Score (KOOS) pain score (improvement) with verum acupuncture compared to the sham acupuncture. Longitudinal cortical thickness analysis showed that the cortical thickness at left posterior medial prefrontal cortex (pMPFC) decreased significantly in the sham group across treatment sessions as compared with verum group. Resting state functional connectivity (rsFC) analysis using the left pMPFC as a seed showed that after longitudinal treatments, the rsFC between the left pMPFC and the rostral anterior cingulate cortex (rACC), medial frontal pole (mFP) and periaquiduct grey (PAG) are significantly greater in the verum acupuncture group as compared with the sham group. Our results suggest that acupuncture may achieve its therapeutic effect on knee OA pain by preventing cortical thinning and decreases in functional connectivity in major pain related areas, therefore modulating pain in the descending pain modulatory pathway.
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http://dx.doi.org/10.1038/srep06482DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4175730PMC
September 2014

Feasible Dose Reduction in Routine Chest Computed Tomography Maintaining Constant Image Quality Using the Last Three Scanner Generations: From Filtered Back Projection to Sinogram-affirmed Iterative Reconstruction and Impact of the Novel Fully Integrated Detector Design Minimizing Electronic Noise.

J Clin Imaging Sci 2014 31;4:38. Epub 2014 Jul 31.

Department of Diagnostic, Interventional and Pediatric Radiology, Inselspital, Bern University Hospital, Freiburgstrasse, Bern, Switzerland.

Objective: The aim of the present study was to evaluate a dose reduction in contrast-enhanced chest computed tomography (CT) by comparing the three latest generations of Siemens CT scanners used in clinical practice. We analyzed the amount of radiation used with filtered back projection (FBP) and an iterative reconstruction (IR) algorithm to yield the same image quality. Furthermore, the influence on the radiation dose of the most recent integrated circuit detector (ICD; Stellar detector, Siemens Healthcare, Erlangen, Germany) was investigated.

Materials And Methods: 136 Patients were included. Scan parameters were set to a thorax routine: SOMATOM Sensation 64 (FBP), SOMATOM Definition Flash (IR), and SOMATOM Definition Edge (ICD and IR). Tube current was set constantly to the reference level of 100 mA automated tube current modulation using reference milliamperes. Care kV was used on the Flash and Edge scanner, while tube potential was individually selected between 100 and 140 kVp by the medical technologists at the SOMATOM Sensation. Quality assessment was performed on soft-tissue kernel reconstruction. Dose was represented by the dose length product.

Results: Dose-length product (DLP) with FBP for the average chest CT was 308 mGy*cm ± 99.6. In contrast, the DLP for the chest CT with IR algorithm was 196.8 mGy*cm ± 68.8 (P = 0.0001). Further decline in dose can be noted with IR and the ICD: DLP: 166.4 mGy*cm ± 54.5 (P = 0.033). The dose reduction compared to FBP was 36.1% with IR and 45.6% with IR/ICD. Signal-to-noise ratio (SNR) was favorable in the aorta, bone, and soft tissue for IR/ICD in combination compared to FBP (the P values ranged from 0.003 to 0.048). Overall contrast-to-noise ratio (CNR) improved with declining DLP.

Conclusion: The most recent technical developments, namely IR in combination with integrated circuit detectors, can significantly lower radiation dose in chest CT examinations.
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http://dx.doi.org/10.4103/2156-7514.137826DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4142483PMC
August 2014

Pulmonary intimal sarcoma: a rare differential diagnosis for arterial filling defects on a chest CT.

Acta Radiol Short Rep 2014 Feb 25;3(2):2047981613514052. Epub 2014 Feb 25.

Inselspital, University Hospital Bern, Departement for Diagnostic, Pediatric and Interventional Radiology, Bern, Switzerland.

We present a rare case of pulmonary intimal sarcoma mimicking pulmonary embolism in a 40-year-old woman. Although extremely rare, these tumors must be considered in patients who present inappropriate imaging findings that suggest embolism. Chest computed tomography is the modality of choice to determine the extent of the tumor. We present a female patient with suspected embolism that was in fact found to be an endothelial sarcoma of the pulmonary arteries.
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http://dx.doi.org/10.1177/2047981613514052DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4001433PMC
February 2014

Stabilization system for holographic recording of volume Bragg gratings using a corner cube retroreflector.

Appl Opt 2014 Feb;53(6):1039-46

Volume Bragg gratings serve an important role in laser development as devices that are able to manipulate both the wavelength and angular spectrum of light. A common method for producing gratings is holographic recording of a two collimated beam interference pattern in a photosensitive material. This process requires stability of the recording system at a level of a fraction of the recording wavelength. A new method for measuring and stabilizing the phase of the recording beams is presented that is extremely flexible and simple to integrate into an existing holographic recording setup and independent of the type of recording media. It is shown that the presented method increases visibility of an interference pattern and for photo-thermo-refractive glass enables enhancement of the spatial refractive index modulation. The use of this technique allows for longer recording times that can lead to the use of expanded recording beams for large aperture gratings.
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http://dx.doi.org/10.1364/AO.53.001039DOI Listing
February 2014

Scaling the spectral beam combining channels in a multiplexed volume Bragg grating.

Opt Express 2013 Dec;21(24):29620-7

In order to generate high power laser radiation it is often necessary to combine multiple lasers into a single beam. The recent advances in high power spectral beam combining using multiplexed volume Bragg gratings recorded in photo-thermo-refractive glass are presented. The focus is on using multiple gratings recorded within the same volume to lower the complexity of the combining system. Combining of 420 W with 96% efficiency using a monolithic, multiplexed double grating recorded in PTR glass is demonstrated. A multiplexed quadruple grating that maintains high efficiency and good beam quality is demonstrated to pave a way for further scaling of combining channels.
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http://dx.doi.org/10.1364/OE.21.029620DOI Listing
December 2013

Effect of aberrations in a holographic system on reflecting volume Bragg gratings.

Appl Opt 2013 Nov;52(32):7826-31

The effect of aberrations in the recording beams of a holographic setup is discussed regarding the deterioration of properties of a reflecting volume Bragg grating. Imperfect recording beams result in a spatially varying grating vector, which causes broadening, asymmetry, and washed out side lobes in the reflection spectrum as well as a corresponding reduction in peak diffraction efficiency. These effects are more significant for gratings with narrower spectral widths.
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http://dx.doi.org/10.1364/AO.52.007826DOI Listing
November 2013

Genetic variation of lodgepole pine, Pinus contorta var. latifolia, chemical and physical defenses that affect mountain pine beetle, Dendroctonus ponderosae, attack and tree mortality.

J Chem Ecol 2011 Sep 16;37(9):1002-12. Epub 2011 Aug 16.

The Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, VT 05405, USA.

Plant secondary chemistry is determined by both genetic and environmental factors, and while large intraspecific variation in secondary chemistry has been reported frequently, the levels of genetic variation of many secondary metabolites in forest trees in the context of potential resistance against pests have been rarely investigated. We examined the effect of tree genotype and environment/site on the variation in defensive secondary chemistry of lodgepole pine, Pinus contorta var. latifolia, against the fungus, Grosmannia clavigera (formerly known as Ophiostoma clavigerum), associated with the mountain pine beetle, Dendroctonus ponderosae. Terpenoids were analyzed in phloem samples from 887, 20-yr-old trees originating from 45 half-sibling families planted at two sites. Samples were collected both pre- and post-inoculation with G. clavigera. Significant variation in constitutive and induced terpenoid compounds was attributed to differences among families. The response to the challenge inoculation with G. clavigera was strong for some individual compounds, but primarily for monoterpenoids. Environment (site) also had a significant effect on the accumulation of some compounds, whereas for others, no significant environmental effect occurred. However, for a few compounds significant family x environment interactions were found. These results suggest that P. c. latifolia secondary chemistry is under strong genetic control, but the effects depend on the individual compounds and whether or not they are expressed constitutively or following induction.
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http://dx.doi.org/10.1007/s10886-011-0003-8DOI Listing
September 2011

Bone images from dual-energy subtraction chest radiography in the detection of rib fractures.

Eur J Radiol 2011 Aug 19;79(2):e28-32. Epub 2010 Feb 19.

Department of Diagnostic, Interventional and Pediatric Radiology, University Hospital Bern, Freiburgstrasse 4, Bern CH-3010, Switzerland.

Objective: To assess the sensitivity and image quality of chest radiography (CXR) with or without dual-energy subtracted (ES) bone images in the detection of rib fractures.

Materials And Methods: In this retrospective study, 39 patients with 204 rib fractures and 24 subjects with no fractures were examined with a single exposure dual-energy subtraction digital radiography system. Three blinded readers first evaluated the non-subtracted posteroanterior and lateral chest radiographs alone, and 3 months later they evaluated the non-subtracted images together with the subtracted posteroanterior bone images. The locations of rib fractures were registered with confidence levels on a 3-grade scale. Image quality was rated on a 5-point scale. Marks by readers were compared with fracture localizations in CT as a standard of reference.

Results: The sensivity for fracture detection using both methods was very similar (34.3% with standard CXR and 33.5% with ES-CXR, p=0.92). At the patient level, both sensitivity (71.8%) and specificity (92.9%) with or without ES were identical. Diagnostic confidence was not significantly different (2.61 with CXR and 2.75 with ES-CXR, p=0.063). Image quality with ES was rated higher than that on standard CXR (4.08 vs. 3.74, p<0.001).

Conclusions: Despite a better image quality, adding ES bone images to standard radiographs of the chest does not provide better sensitivity or improved diagnostic confidence in the detection of rib fractures.
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http://dx.doi.org/10.1016/j.ejrad.2010.01.016DOI Listing
August 2011

Computed tomographic coronary angiography in patients with surgically treated type A aortic dissection: preliminary results.

Emerg Radiol 2010 May;17(3):185-90

Radiology, Bern University Hospital, Bern, Switzerland.

Acute type A aortic dissection is a serious emergency with a mortality rate of up to 40% within the first 24 h when left untreated. Surgical therapy needs to be initiated promptly. Due to this urgent situation, preoperative evaluation of the coronary arteries is not routinely performed in these patients. The aim of this study was to evaluate the accuracy of 64-slice computed tomography angiography (CTA) for postoperative coronary artery assessment in these patients. Ten consecutive patients with two or more cardiovascular risk factors were prospectively enrolled. Patients had type A aortic dissection treated surgically with a supracoronary graft of the ascending aorta. Performance of CTA to exclude significant stenosis (>50% lumen narrowing) and/or coronary artery dissection was compared with quantitative coronary angiography. A total of 147 segments were evaluated. Three segments (2%) were excluded from analysis. CTA correctly assessed one of three significant stenoses in three patients and correctly excluded coronary artery disease (CAD) in six of ten patients. One patient was rated false positive. Overall accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CT for identifying coronary artery disease by segment was 98%, 33%, 99%, 50%, and 99%, respectively (P<0.05). By patient, it was 70%, 33%, 86%, 50%, and 75%, respectively. No coronary artery dissection was found. Noninvasive CTA may be a viable alternative to conventional angiography for postoperative coronary artery evaluation in patients with surgically treated type A aortic dissection and cardiovascular risk factors. An NPV of 99% should allow for reliable exclusion of CAD. Further studies with higher patient numbers are warranted.
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http://dx.doi.org/10.1007/s10140-009-0829-3DOI Listing
May 2010

Images in cardio-thoracic surgery: Ruptured pseudoaneurysm with aorto-pulmonary shunt after aortic arch repair.

Eur J Cardiothorac Surg 2009 May 10;35(5):901. Epub 2009 Mar 10.

Department of Cardiovascular Surgery, University Hospital of Berne, Switzerland.

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http://dx.doi.org/10.1016/j.ejcts.2008.12.051DOI Listing
May 2009

Neuregulin-1 beta attenuates doxorubicin-induced alterations of excitation-contraction coupling and reduces oxidative stress in adult rat cardiomyocytes.

J Mol Cell Cardiol 2006 Nov 26;41(5):845-54. Epub 2006 Sep 26.

Swiss Cardiovascular Center, University Hospital, CH-3010 Bern, Switzerland.

Treatment of metastatic breast cancer with doxorubicin (Doxo) in combination with trastuzumab, an antibody targeting the ErbB2 receptor, results in an increased incidence of heart failure. Doxo therapy induces reactive oxygen species (ROS) and alterations of calcium homeostasis. Therefore, we hypothesized that neuregulin-1 beta (NRG), a ligand of the cardiac ErbB receptors, reduces Doxo-induced alterations of EC coupling by triggering antioxidant mechanisms. Adult rat ventricular cardiomyocytes (ARVM) were isolated and treated for 18-48 h. SERCA protein was analyzed by Western blot, EC coupling parameters by fura-2 and video edge detection, gene expression by RT-PCR, and ROS by DCF-fluorescence microscopy. At clinically relevant doses Doxo reduced cardiomyocytes contractility, SERCA protein and SR calcium content. NRG, similarly as the antioxidant N-acetylcystein (NAC), did not affect EC coupling alone, but protected against Doxo-induced damage. NRG and Doxo showed an opposite modulation of glutathione reductase gene expression. NRG, similarly as NAC, reduced peroxide- or Doxo-induced oxidative stress. Specific inhibitors showed, that the antioxidant action of NRG depended on signaling via the ErbB2 receptor and on the Akt- and not on the MAPK-pathway. Therefore, NRG attenuates Doxo-induced alterations of EC coupling and reduces oxidative stress in ARVM. Inhibition of the ErbB2/NRG signaling pathway by trastuzumab in patients concomitantly treated with Doxo might prevent beneficial effects of NRG in the myocardium.
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http://dx.doi.org/10.1016/j.yjmcc.2006.08.002DOI Listing
November 2006