Second-harmonic aberration correction

A simulation study is performed to present results concerning 3D aberration correction for harmonic imaging. Two different correction schemes (a pure time-delay correction and a time-delay and amplitude correction) are employed along with estimation based on either the received first- or second-harmonic frequency. An aberrating body wall is implemented as a 20 mm delay-screen body wall using eight screens, and is tuned to match human abdominal wall characteristics. The transmit pressure of the first harmonic is set to not succeed a mechanical index of 1.1 for the uncorrected case and a pure time-delay correction. Using a time-delay and amplitude correction, the total acoustic energy transmitted is equal to that of the uncorrected case. The total amount of generated second-harmonic energy increases with approximately 1 dB for a pure time-delay correction and about 2 dB for a time-delay and amplitude correction, both estimated at the received first-harmonic frequency. The general side-lobe level of the first- and second-harmonic focal point beam profile averaged over circles around the transducer axis is lowered with 2-10 dB for both correction schemes relative to the uncorrected case

Abersim: a Simulation Program for 3D Nonlinear Acoustic Wave Propagation for Arbitrary Pulses and Arbitrary Transducer Geometries, Evaluation of diffraction and attenuation

Abersim, a simulation package for 3D nonlinear wave propagation of wide-band pulses from arbitrary,is presented. This study validates the 3D diffraction attenuation produced by Abersim, by comparing them to obtained using Field II. For the presented tes

Harmonic source wavefront aberration correction for ultrasound imaging

A method is proposed which uses a lower-frequency transmit to create a known harmonic acoustical source in tissue suitable for wavefront correction without a priori assumptions of the target or requiring a transponder. The measurement and imaging steps of this method were implemented on the Duke phased array system with a two-dimensional (2-D) array. The method was tested with multiple electronic aberrators [0.39π to 1.16π radians root-mean-square (rms) at 4.17 MHz] and with a physical aberrator 0.17π radians rms at 4.17 MHz) in a variety of imaging situations. Corrections were quantified in terms of peak beam amplitude compared to the unaberrated case, with restoration between 0.6 and 36.6 dB of peak amplitude with a single correction. Standard phantom images before and after correction were obtained and showed both visible improvement and 14 dB contrast improvement after correction. This method, when combined with previous phase correction methods, may be an important step that leads to improved clinical images

Benzene exposure and risk of lung cancer in the Norwegian Offshore Petroleum Worker cohort: a prospective case-cohort study

Objective The objective of our study was to examine whether occupational exposure to benzene is associated with lung cancer among males in the Norwegian Offshore Petroleum Workers cohort. Methods Among 25 347 male offshore workers employed during 1965–1998, we conducted a case-cohort study with 399 lung cancer cases diagnosed between 1999 and 2021, and 2035 non-cases sampled randomly by 5-year birth cohorts. Individual work histories were coupled to study-specific job-exposure matrices for benzene and other known lung carcinogens. Weighted Cox regression was used to estimate HRs and 95% CIs for the associations between benzene exposure and lung cancer, by major histological subtypes, adjusted for age, smoking and occupational exposure to welding fumes, asbestos and crystalline silica. Missing data were imputed. Results For lung cancer (all subtypes combined), HRs (95% CIs) for the highest quartiles of benzene exposure versus unexposed were 1.15 (0.61 to 2.35) for cumulative exposure, 1.43 (0.76 to 2.69) for duration, and 1.22 (0.68 to 2.18) for average intensity (0.280≤P-trend≤0.741). For 152 adenocarcinoma cases, a positive trend was observed for exposure duration (P-trend=0.044). Conclusions In this cohort of offshore petroleum workers generally exposed to low average levels of benzene, we did not find an overall clear support for an association with lung cancer (all subtypes combined), although an association was suggested for duration of benzene exposure and adenocarcinoma. The limited evidence might be due to restricted statistical power.publishedVersio

Voices from the North: Stories About Active Ageing, Everyday Life and Home-Based Care Among Older People in Northern Norway

What is the meaning of active ageing in the daily life of frail older people in need of comprehensive home-based care services? This chapter addresses this question using in-depth interviews with women and men aged 70-97 in Northern Norway. The chapter illustrates first, that some older women and men actually prefer to age actively within their home by doing activities such as reading books, solving Sudoku, watching TV and watching birds at the bird feeder. Second, it illustrates the key role potentially played by the next of kin in helping older relatives with different practical issues that may have major impacts on their social well-being. Third, we provide evidence for the limits of public care services in supporting older people with no or few relatives who, also whe

Exposure to benzene and other hydrocarbons and risk of bladder cancer among male offshore petroleum workers

Background Occupational exposures constitute the second leading cause of urinary bladder cancer after tobacco smoking. Increased risks have been found in the petroleum industry, but high-quality exposure data are needed to explain these observations. Methods Using a prospective case-cohort design, we analysed 189 bladder cancer cases (1999–2017) and 2065 randomly drawn non-cases from the Norwegian Offshore Petroleum Workers cohort. Cases were identified in the Cancer Registry of Norway, while work histories (1965–1998) and lifestyle factors were recorded by questionnaire at baseline (1998). Occupational petroleum-related hydrocarbon exposures were assessed by expert-developed job-exposure matrices. Hazard ratios were estimated by weighted Cox-regressions, adjusted for age, tobacco smoking, education, and year of first employment, and with lagged exposures. Results Increased risks were found in benzene-exposed workers, either long-term exposure (≥18.8 years, HR = 1.89, 95% CI: 1.14–3.13; p-trend = 0.044) or high-level cumulative benzene exposure (HR = 1.60, 95% CI: 0.97–2.63; p-trend = 0.065), compared with the unexposed. Associations persisted with 20-year exposure lag. No associations were found with skin or inhalation exposure to crude oil, mineral oil (lubrication, hydraulics, turbines, drilling), or diesel exhaust. Conclusions The results suggest that exposures in the benzene fraction of the petroleum stream may be associated with increased bladder cancer risk.publishedVersio

Night shift work, chemical coexposures and risk of female breast cancer in the Norwegian Offshore Petroleum Workers (NOPW) cohort: a prospectively recruited case-cohort study

Objectives This study examined the association between night shift work and risk of breast cancer, overall and by hormone receptor subtype, among females in the Norwegian Offshore Petroleum Workers (NOPW) cohort. We also examined the association of coexposure (chlorinated degreasers and benzene) and breast cancer risk, and possible interaction with work schedule. Design Prospectively recruited case-cohort study within the NOPW cohort. Setting Female offshore petroleum workers active on the Norwegian continental shelf. Participants 600 female workers (86 cases and 514 non-cases) were included in the study. We excluded workers that died or emigrated before start of follow-up, had missing work history, were diagnosed with breast cancer or other prior malignancy (except non-melanoma skin cancer) before start of follow-up. Results No overall association was found between breast cancer risk and work schedule (HR 0.87, 95% CI 0.52 to 1.46 for work schedule involving night shift vs day shift only). There was no significant association between work schedule and risk of any breast cancer subtype. No significant interactions were found between work schedule and chemical coexposures (breast cancer overall Pinteraction chlorinated degreasers=0.725 and Pinteraction benzene=0.175). Conclusions Our results did not provide supporting evidence that work schedule involving night shift affects breast cancer risk in female offshore petroleum workers, but should be considered cautiously due to few cases. Further studies with larger sample sizes are warranted

Night shift work, chemical coexposures and risk of female breast cancer in the Norwegian Offshore Petroleum Workers (NOPW) cohort: A prospectively recruited case-cohort study

Objectives This study examined the association between night shift work and risk of breast cancer, overall and by hormone receptor subtype, among females in the Norwegian Offshore Petroleum Workers (NOPW) cohort. We also examined the association of coexposure (chlorinated degreasers and benzene) and breast cancer risk, and possible interaction with work schedule. Design Prospectively recruited case-cohort study within the NOPW cohort. Setting Female offshore petroleum workers active on the Norwegian continental shelf. Participants 600 female workers (86 cases and 514 non-cases) were included in the study. We excluded workers that died or emigrated before start of follow-up, had missing work history, were diagnosed with breast cancer or other prior malignancy (except non-melanoma skin cancer) before start of follow-up. Results No overall association was found between breast cancer risk and work schedule (HR 0.87, 95% CI 0.52 to 1.46 for work schedule involving night shift vs day shift only). There was no significant association between work schedule and risk of any breast cancer subtype. No significant interactions were found between work schedule and chemical coexposures (breast cancer overall P interaction chlorinated degreasers =0.725 and P interaction benzene =0.175). Conclusions Our results did not provide supporting evidence that work schedule involving night shift affects breast cancer risk in female offshore petroleum workers, but should be considered cautiously due to few cases. Further studies with larger sample sizes are warranted

Cohort Profile: The Norwegian Offshore Petroleum Workers (NOPW) Cohort

publishedVersio

Matrix-IR spectroscopic investigations of the thermolysis and photolysis of diazoamides

Matrix photolysis of N,N-dialkyldiazoacetamides 1a-d at 7-10 K results in either the formation of C-H insertion products (in case of N,N-dimethyl and N,N-diethyl diazoamides) or almost exclusive Wolff rearrangement to ketenes (in the case of the cyclic diazoamides N-(diazoacetyl)azetidine and N-(diazoacetyl)pyrrolidine). This can be ascribed to higher activation barriers for the approach of the singlet carbene p orbital in 5 (or of the diazo carbon in an excited state of 1) to the stronger and "tied back" nature of the C-H bonds in the cyclic substituents. In contrast, flash vacuum thermolysis (FVT) of diazoamides 1a-d, in which reactions of excited states are excluded, gives rise to clean C-H insertion with only minor Wolff rearrangement to ketenes