| 1. |
- Amundin, Mats, 1947-, et al.
(author)
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An echolocation visualization and interface system for dolphin research
- 2008
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In: Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 0001-4966 .- 1520-8524. ; 123:2, s. 1188-1194
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Journal article (peer-reviewed)abstract
- The present study describes the development and testing of a tool for dolphin research. This tool was able to visualize the dolphin echolocation signals as well as function as an acoustically operated "touch screen." The system consisted of a matrix of hydrophones attached to a semitransparent screen, which was lowered in front of an underwater acrylic panel in a dolphin pool. When a dolphin aimed its sonar beam at the screen, the hydrophones measured the received sound pressure levels. These hydrophone signals were then transferred to a computer where they were translated into a video image that corresponds to the dynamic sound pressure variations in the sonar beam and the location of the beam axis. There was a continuous projection of the image back onto the hydrophone matrix screen, giving the dolphin an immediate visual feedback to its sonar output. The system offers a whole new experimental methodology in dolphin research and since it is software-based, many different kinds of scientific questions can be addressed. The results were promising and motivate further development of the system and studies of sonar and cognitive abilities of dolphins. © 2008 Acoustical Society of America.
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| 2. |
- Glimelius, Bengt, et al.
(author)
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A randomized phase III multicenter trial comparing irinotecan in combination with the Nordic bolus 5-FU and folinic acid schedule or the bolus/infused de Gramont schedule (Lv5FU2) in patients with metastatic colorectal cancer
- 2008
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In: Annals of Oncology. - : Elsevier BV. - 0923-7534 .- 1569-8041. ; 19:5, s. 909-914
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Journal article (peer-reviewed)abstract
- Background: To compare irinotecan with the Nordic 5-fluorouracil (5-FU) and folinic acid (FA) bolus schedule [irinotecan 180 mg/m2 on day 1, 5-FU 500 mg/m2 and FA 60 mg/m2 on day 1 and 2 (FLIRI)] or the Lv5FU2 schedule [irinotecan 180 mg/m2 on day 1, FA 200 mg/m2, 5-FU bolus 400 mg/m2 and infused 5-FU 600 mg/m2 on day 1 and 2 (Lv5FU2-IRI)] due to uncertainties about how to administrate 5-FU with irinotecan. Patients and methods: Patients (n = 567) with metastatic colorectal cancer were randomly assigned to receive FLIRI or Lv5FU2-IRI. Primary end point was progression-free survival (PFS). Results: Patient characteristics were well balanced. PFS did not differ between groups (median 9 months, P = 0.22). Overall survival (OS) was also similar (median 19 months, P = 0.9). Fewer objective responses were seen in the FLIRI group (35% versus 49%, P = 0.001) but the metastatic resection rate did not differ (4% versus 6%, P = 0.3). Grade 3/4 neutropenia (11% versus 5%, P = 0.01) and grade 2 alopecia (18% versus 9%, P = 0.002) were more common in the FLIRI group. The 60-day mortality was 2.4% versus 2.1%. Conclusions: Irinotecan with the bolus Nordic schedule (FLIRI) is a convenient treatment with PFS and OS comparable to irinotecan with the Lv5FU2 schedule. Neutropenia and alopecia are more prevalent, but both regimens are equally well tolerated. © The Author 2008. Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved.
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| 3. |
- Glimelius, Bengt, et al.
(author)
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Adjuvant chemotherapy in colorectal cancer: a joint analysis of randomised trials by the Nordic Gastrointestinal Tumour Adjuvant Therapy Group
- 2005
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In: Acta Oncol. - : Informa UK Limited. - 0284-186X .- 1651-226X. ; 44:8, s. 904-12
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Journal article (peer-reviewed)abstract
- Due to uncertainties regarding clinically meaningful gains from adjuvant chemotherapy after colorectal cancer surgery, several Nordic Groups in the early 1990s initiated randomised trials to prove or reject such gains. This report gives the joint analyses after a minimum 5-year follow-up. Between October 1991 and December 1997, 2 224 patients under 76 years of age with colorectal cancer stages II and III were randomised to surgery alone (n = 1 121) or adjuvant chemotherapy (n = 1 103) which varied between trials (5FU/levamisole for 12 months, n = 444; 5FU/leucovorin for 4-5 months according to either a modified Mayo Clinic schedule (n = 262) or the Nordic schedule (n = 397). Some centres also randomised patients treated with 5FU/leucovorin to+/-levamisole). A total of 812 patients had colon cancer stage II, 708 colon cancer stage III, 323 rectal cancer stage II and 368 rectal cancer stage III. All analyses were according to intention-to-treat. No statistically significant difference in overall survival, stratified for country or region, could be found in any group of patients according to stage or site. In colon cancer stage III, an absolute difference of 7% (p = 0.15), favouring chemotherapy, was seen. The present analyses corroborate a small but clinically meaningful survival gain from adjuvant chemotherapy in colon cancer stage III, but not in the other presentations.
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| 4. |
- Hardell, L, et al.
(author)
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Concentrations of polychlorinated biphenyls in blood and the risk for testicular cancer
- 2004
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In: International Journal of Andrology. - : Wiley. - 0105-6263 .- 1365-2605. ; 27:5, s. 282-290
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Journal article (peer-reviewed)abstract
- An increasing incidence of testicular cancer has been reported from several western countries during the last decades. According to current hypothesis testicular cancer is initiated during the foetal period and exposure to endocrine disruptors such as some persistent organic pollutants has been of concern. We have previously reported the results for concentrations of polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyl-dichloroethylene (pp'-DDE), hexachlorobenzene (HCB) and chlordanes in 58 cases with testicular cancer, 61 age-matched controls and 44 case mothers and 45 control mothers. In that report, significant increase of odds ratio (OR) was found for sum of PCBs, HCB, trans- and cis-nonachlordane in case mothers. These data have now been further analysed for 37 congeners of PCBs. No significant differences were found among cases and controls. However, case mothers had significantly increased concentrations of a number of PCB congeners. A priori decided grouping of PCBs yielded for oestrogenic PCBs OR = 2.4, 95% confidence interval (CI) = 0.95-6.0, enzyme-inducing PCBsOR = 2.6, 95% CI = 1.03-6.5 and toxic equivalents (TEQ) yielded OR = 3.3, 95% CI = 1.3-8.4. These data further elucidate the role of foetal exposure to different PCB congeners in the aetiology of testicular cancer.
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| 5. |
- Hardell, L, et al.
(author)
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Increased concentrations of polychlorinated biphenyls, hexachlorobenzene, and chlordanes in mothers of men with testicular cancer
- 2003
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In: Journal of Environmental Health Perspectives. - : Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 111:7, s. 930-934
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Journal article (peer-reviewed)abstract
- An increasing incidence of testicular cancer has been reported from several countries in the Western world during the last decades. According to current hypothesis, testicular cancer is initiated during the fetal period, and exposure to endocrine disruptors, i.e., xenoestrogens, has been of concern. In this investigation we studied the concentrations of the sum of 38 polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyl-dichloroethylene, hexachlorobenzene (HCB), and chlordanes, in 61 cases with testicular cancer and 58 age-matched controls. Furthermore, case and control mothers were also asked to participate, and 44 case mothers and 45 control mothers agreed. They were of similar age. In cases only the concentration on lipid basis of cis-nonachlordane was significantly increased, whereas case mothers showed significantly increased concentrations of the sum of PCBs, HCB, trans- and cis-nonachlordane, and the sum of chlordanes. Among case mothers the sum of PCBs yielded an odds ratio (OR) of 3.8, 95% confidence interval (CI), 1.4-10 was calculated using the median concentration for the control mothers as cutoff value. For HCB, OR = 4.4 (95% CI, 1.7-12), for trans-nonachlordane, OR = 4.1 (95% CI, 1.5-11), for cis-nonachlordane, OR = 3.1 (95% CI, 1.2-7.8), and for sum of chlordanes, OR = 1.9 (95% CI, 0.7-5.0). No consistent different risk pattern was found for seminoma. or nonseminoma testicular cancer.
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| 6. |
- Starkhammar, Josefin, et al.
(author)
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Acoustic Touch Screen for Dolphins, First application of ELVIS - an Echo-Location Visualization and Interface System
- 2007
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In: 4th International Conference on Bio-Acoustics 2007. - 1478-6095. - 9781604238082 ; 29:part 3, s. 63-68
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Conference paper (peer-reviewed)abstract
- Dolphin sonar has been extensively studied over several decades, and much of its basic characteristics are well known (Au 1993). However, most of these studies have been based on an experimental setup where the dolphin has been trained to be voluntarily fixed, so its directional sonar beam could be recorded with fixed hydrophones. Although this allows for very exact measurements, it most likely has prevented the full dynamic potential of the dolphin’s sonar to be revealed. Also the dolphin’s response to scientific questions, e.g. in target detection threshold or discrimination trials, mostly has been a “go/no go” response or pressing a yes/no paddle. This traditional experimental methodology to measure the response makes rather coarse indications of choice. It is difficult to refine and will be unpractical with a multi-choice paradigm. Therefore a new EchoLocation Visualisation and Interface System (ELVIS) has been developed at Lund University in cooperation with Kolmården Wild Animal Park, and is presently being used in dolphin food preference investigations at the Kolmården Dolphinarium. ELVIS basically consists of a matrix of 16 hydrophones attached to a semi transparent screen lowered into the water of the pool where the dolphins swim freely. The hydrophones hit by a sonar pulse generate electric signals in relation to the received sound pressure level. After subsequent amplification these signals are transferred to a computer. The signal analysis is performed by custom designed LabVIEW software that constitutes the core of the interactive features of the interface system. The software can for example in real time create a round colour spot on the computer screen, corresponding to the maximum intensity in the sound beam. The recorded sound intensity can be coded into colour and/or light intensity. The resulting image on the computer screen is continuously projected back onto the hydrophone matrix screen, hence giving the dolphin an immediate visual feedback to its sonar output. Since only 16 hydrophones were used, the exact location of the maximum sound intensity point was derived through interpolation between the hydrophones in the matrix. This made the spatial resolution of the sound beam recordings quite sufficient for the present study. However, future systems will certainly rely on increased hydrophone matrix size. This system offers a whole new experimental methodology in dolphin research since it can function as an acoustic “touch screen” for the dolphins. It is highly adaptable to different studies since the core of the interface features is software based.In cognitive studies with primates, e.g. the chimpanzee, a computerized symbol interface, based on a finger operated touch screen, has been successfully used (Rumbaugh et al. 1975). Even with birds, like chickens and doves, this approach has been used (Cheng & Spetch, 1995). So far, however, it has not been attempted with dolphins, partly due to the inherent problems in using electronics in salt water. However, the ELVIS screen is based on acoustic detection and activation, using hydrophones, which is well suited for underwater use. The software used in the present experiment designate active areas on the screen, indicated by white symbols, e.g. a filled circle or a filled square. When the dolphin aims its sonar beam axis at this symbol, it flashes to indicate a “hit” and a bridging stimulus (a 400 ms, 10 kHz sinus tone) is played. In this study each of four such symbols represented a different fish (herring, mackerel, capelin and squid). When the dolphin “clicked” on one of them, it was rewarded by the fish represented by it. Thereby the dolphin could choose what kind of fish it preferred. Hence, for the first time the dolphins could execute and run a computer program using their sonar beam like we use a mouse cursor. The size and trig level of these “buttons” or active areas of the screen can easily be altered so that, as the dolphin’s skills in handling the program increased, the more accurate hits and more distinct sound pressure levels of the dolphin’s sound beam could be required.Three bottlenose dolphins (Tursiops truncatus) were trained to perform the task of pointing their sonar beam selectively on the symbols shown on the ELVIS screen. They quickly learned this task and were highly motivated to explore it.
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| 7. |
- Starkhammar, Josefin, et al.
(author)
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Design and benchmark tests of a hydrophone array system for whale echolocation recordings
- 2012
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In: Open Journal of Acoustics. - : Scientific Research Publishing, Inc.. - 2162-5794 .- 2162-5786. ; 2:3, s. 121-130
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Journal article (peer-reviewed)abstract
- This paper describes in depth the design and application considerations of a computer based measurement system enabling 1 MS/s simultaneous sampling of 47 hydrophones for cross sectional recordings of echolocation beams of toothed whales (Odontocetes). An earlier prototype version of the system has previously only been presented as a brief proof of principle that did not offer a complete description of the software and hardware solution. Crucial hardware and software design considerations of the further developed system include the re-arm times of the burst mode sampling and the dual-core distributed execution of the software components. The rearm time was measured to 283 µs, using a 550 µs long sample window around each click. This enables burst mode sampling of clicks with an inter-click interval as short as 833 µs. It is shown through both synthetic benchmark tests of the system and through field measurements of bottlenose dolphins (Tursiops truncatus) and a beluga whale (Delphinapterus leucas) that it is capable of acquiring, analyzing and visualizing data in run-time. It operates effectively also in highly reverberant surroundings like concrete pools and shallow waters. Burst mode sampling allows the system to block reflections with 0.3 - 0.5 m longer propagation paths than the direct path. It is suggested that the system’s compliance to reverberant recording sites makes it valuable in future dolphin echolocation studies.
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| 8. |
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| 9. |
- Starkhammar, Josefin, et al.
(author)
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Editorial: 47-channel burst-mode recording hydrophone system enabling measurements of the dynamic echolocation behavior of free-swimming dolphins
- 2009
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In: Journal of the Acoustical Society of America. - : A I P Publishing LLC. - 0001-4966 .- 1520-8524. ; 126:3, s. 959-962
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Journal article (other academic/artistic)abstract
- Detailed echolocation behavior studies on free-swimming dolphins require a measurement system that incorporates multiple hydrophones (often andgt; 16). However, the high data flow rate of previous systems has limited their usefulness since only minute long recordings have been manageable. To address this problem, this report describes a 47-channel burst-mode recording hydrophone system that enables highly resolved full beamwidth measurements on multiple free-swimming dolphins during prolonged recording periods. The system facilitates a wide range of biosonar studies since it eliminates the need to restrict the movement of animals in order to study the fine details of their sonar beams.
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| 10. |
- Starkhammar, Josefin, et al.
(author)
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Separating overlapping click trains originating from multiple individuals in echolocation recordings
- 2011
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In: JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA. - : Acoustical Society of America. - 0001-4966 .- 1520-8524. ; 129:1, s. 458-466
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Journal article (peer-reviewed)abstract
- Recordings of the acoustic activity of free-swimming groups of echolocating dolphins increase the likelihood of collecting overlapping click trains, originating from multiple individuals, in the same set of data. In order to evaluate the click properties of each individual based on such recordings it is necessary to identify which clicks originate from which animal. This paper suggests a computationally efficient strategy to separate overlapping click trains originating from multiple free-swimming bottlenose dolphins, enabling echolocation analysis at an individual level on several animals. This technique is based on sequential matching of the frequency spectra of successive clicks. The clicks are grouped together as individual click trains if the correlation coefficients between clicks are higher than a pre-set threshold level. The robustness of the algorithm is tested by adding artificially generated white Gaussian noise and comparing the results with other comparable commonly used methods based on inter-click intervals, centroid frequencies, and amplitude levels. The described method is applicable to a variety of experimental and observational contexts, e. g., those regarding echolocation development of calves, the hypothesized acoustic "etiquette" among dolphins when investigating the same object, and the possible occurrence of eavesdropping in large dolphin pods.
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