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Osteoporosis is more common in patients with COPD and in smokers. The aim of this study was to assess whether measures of emphysema and airway disease on computed tomography (CT) were associated with lower bone density or vertebral fractures in smokers with and without COPD. For this purpose, we included participants from the NELSON lung cancer screening trial. Bone density was measured as Hounsfield Units in the first lumbar vertebra, and vertebral fractures were assessed semiquantitatively. The 15th percentile method (Perc15) was used to assess emphysema, and the airway lumen perimeter (Pi10) was used for airway wall thickness. Expiratory/inspiratory-ratiomean lung density (E/I-ratioMLD) was used as a measure for air trapping and tracheal index to assess tracheal deformity. Linear regression models and logistic regression models were used to assess associations between CT biomarkers, bone density, and presence of fractures. Exactly 1,093 male participants were eligible for analysis. Lower Perc15 and higher E/I-ratioMLD were significantly associated with lower bone density (b=-1.27, P=0.02 and b=-0.37, P=0.02, respectively). Pi10 and tracheal index were not associated with bone density changes. CT-derived biomarkers were not associated with fracture prevalence. Bone density is lower with increasing extent of emphysema and small airway disease but is not associated with large airway disease and tracheal deformity. This may indicate the necessity to measure bone density early in smokers with emphysema and air trapping to prevent vertebral fractures.

Objective: To determine inter-observer and inter-examination variability of manual attenuation measurements of the vertebrae in low-dose unenhanced chest computed tomography (CT). Methods: Three hundred and sixty-seven lung cancer screening trial participants who underwent baseline and repeat unenhanced low-dose CT after 3 months because of an indeterminate lung nodule were included. The CT attenuation value of the first lumbar vertebrae (L1) was measured in all CTs by one observer to obtain inter-examination reliability. Six observers performed measurements in 100 randomly selected CTs to determine agreement with limits of agreement and Bland-Altman plots and reliability with intraclass correlation coefficients (ICCs). Reclassification analyses were performed using a threshold of 110 HU to define osteoporosis. Results: Inter-examination reliability was excellent with an ICC of 0.92 (p < 0.001). Inter-examination limits of agreement ranged from -26 to 28 HU with a mean difference of 1 ± 14 HU. Inter-observer reliability ICCs ranged from 0.70 to 0.91. Inter-examination variability led to 11.2 % reclassification of participants and inter-observer variability led to 22.1 % reclassification. Conclusions: Vertebral attenuation values can be manually quantified with good to excellent inter-examination and inter-observer reliability on unenhanced low-dose chest CT. This information is valuable for early detection of osteoporosis on low-dose chest CT. Key Points: • Vertebral attenuation values can be manually quantified on low-dose unenhanced CT reliably.• Vertebral attenuation measurements may be helpful in detecting subclinical low bone density.• This could become of importance in the detection of osteoporosis.

The overwhelming post splenectomy infection (OPSI) in splenectomised patients is a rare but severe infection mostly caused by encapsulated bacteria. We analyse the case of a 65-year-old female patient who was presented with clinical and laboratory findings indicating gastroenteritis. Two years years before admission, the patient underwent a splenectomy for a two stage splenic rupture following resuscitation for pulmonary embolism. Immunisation of the patient was complete and timely. As a result of the unspecific clinical presentation, there was a delay in administration of antibiotics. However, administration of antibiotics induced a fulminant shock. The patient died 4 hours after attending the hospital due to a pneumococcal sepsis. The discussion highlights epidemiological and pathophysiological aspects and potential prevention strategies in the international context. Vaccination failed in our patient as the isolated pneumococcal strain (serogroup: 12F) is usually covered by the 23-valent pneumococcal polysaccharide vaccination (Pneumovax®). The case reported here indicates that there may be a potential benefit of prophylactic antibiotic treatment within the first 3 years after splenectomy for patients above the age of 65 years. Awareness of OPSI (prevention strategies, symptoms and treatment) among patients and their treating physicians is crucial for the improvement of prognosis. We partly address these issues in a standard operating procedure for the assessment of splenectomised patients in our departments of emergency medicine., Die Post-Splenektomie-Sepsis ist eine seltene, häufig tödlich verlaufende Erkrankung bei splenektomierten Patienten, die überwiegend durch kapseltragende Bakterien verursacht wird. Wir berichten den Fall einer 65-jährigen Patientin, die sich aufgrund von seit 12 Stunden bestehendem, allgemeinen Krankheitsgefühl, Übelkeit, Erbrechen und Durchfall in der Notaufnahme vorstellte. Zwei Jahre zuvor war sie aufgrund einer fulminanten Lungenembolie reanimationspflichtig geworden. Im Anschluss daran entwickelte die Patientin eine zweizeitige Milzruptur. Die Milz wurde entfernt und empfohlene Impfungen zeitgerecht verabreicht. Die Zusammenschau der initial erhobenen Befunde machte die Diagnose einer Gastroenteritis wahrscheinlich. Dies wiederum führte zu einer verzögerten Antibiotikagabe. Die Antibiotikagabe wiederum löste ein fulminantes Schockgeschehen aus. Die Patientin verstarb 4 Stunden nach Krankenhausaufnahme an einer Post-Splenektomie-Pneumokokken-Sepsis. Die Diskussion widmet sich der Epidemiologie der Erkrankung, dem Verlauf der Erkrankung und den möglichen Präventionsstrategien. In der Zusammenschau kann die Aufklärung der betroffenen Patienten über die Notwendigkeit, auch bei geringen Infektionssymptomen ihren Arzt aufzusuchen nicht überbewertet werden. Auch die Bereitschaft der behandelnden Ärzte, auf den bloßen Verdacht hin bereits intravenös Antibiotika zu verabreichen, ist mitentscheidend. Wir haben daher eine Standard-Arbeitsanweisung für splenektomierte Patienten in unseren Notaufnahmen implementiert. Zudem wirft die Diskussion des Falles die Frage eines möglichen Nutzens einer prophylaktischen Antibiotika-Therapie bei über 65-jährigen Patienten auf (analog zu den Empfehlungen für Kinder).

Esther Pompe,1 Pim A de Jong,2 Eva M van Rikxoort,3 Leticia Gallardo Estrella,3 Werner U de Jong,2 Rozemarijn Vliegenthart,4,5 Matthijs Oudkerk,5 Carlijn M van der Aalst,6 Bram van Ginneken,3 Jan-Willem J Lammers,1 Firdaus AA Mohamed Hoesein2 1Department of Pulmonology, 2Department of Radiology, University Medical Center Utrecht, Utrecht, 3Department of Radiology, Radboud University Medical Center, Nijmegen, 4Center for Medical Imaging-North East Netherlands, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands; 5Department of Radiology, University of Groningen, University Medical Center Groningen, Groningen, 6Department of Public Health, Erasmus Medical Center, Rotterdam, the Netherlands Abstract: Osteoporosis is more common in patients with COPD and in smokers. The aim of this study was to assess whether measures of emphysema and airway disease on computed tomography (CT) were associated with lower bone density or vertebral fractures in smokers with and without COPD. For this purpose, we included participants from the NELSON lung cancer screening trial. Bone density was measured as Hounsfield Units in the first lumbar vertebra, and vertebral fractures were assessed semiquantitatively. The 15th percentile method (Perc15) was used to assess emphysema, and the airway lumen perimeter (Pi10) was used for airway wall thickness. Expiratory/inspiratory-ratiomean lung density (E/I-ratioMLD) was used as a measure for air trapping and tracheal index to assess tracheal deformity. Linear regression models and logistic regression models were used to assess associations between CT biomarkers, bone density, and presence of fractures. Exactly 1,093 male participants were eligible for analysis. Lower Perc15 and higher E/I-ratioMLD were significantly associated with lower bone density (b=-1.27, P=0.02 and b=-0.37, P=0.02, respectively). Pi10 and tracheal index were not associated with bone density changes. CT-derived biomarkers were not associated

There has been a long history of debate over the extent and timing of past glaciations on the small but climatically-sensitive islands of the sub-Antarctic. The largest of these islands, South Georgia, has been the focus of contention with two conflicting models proposed for the peak of the last glaciation (the Last Glacial Maximum, c. 21 k yrs B.P.): one suggesting an ice cap of restricted extent that saw tidewater outlets limited to the coastal basins of radial fjords; the other proposing an extensive shelf-wide ice cap based on well-preserved though as yet un-dated or un-sampled sea-bed geomorphology. It has been suggested that these two models form comparative end-members of 'South American‘ (restricted) and 'Antarctic‘ (extensive) modes of glaciation, and thus establishing whether the pattern of glaciation on sub- Antarctic islands follows one of these modes, or is in itself entirely different, can provide potentially important insight into past climate forcing of an otherwise poorly-constrained Southern Ocean region. The extent of island glaciation can also provide valuable far-field constraint for Antarctic ice sheet models, and forms vital information for biologists seeking to understand benthic marine communities around South Georgia, whose evolution and structure are intimately linked to the long-term history of ice advance and retreat. Here we investigate the geological record offshore of South Georgia to improve understanding of the extent and timing of past glaciation. Marine geophysical data from new and previous research cruises have been compiled and analysed to advance knowledge of palaeo-ice cap dynamics on the island‘s submerged sea bed and subsurface. We have also sought an independent verification of the glacial history of the island by linking new geomorphological analyses with dated marine sedimentary records recovered by coring, for the first time, on the continental shelf. We present results of new landform mapping on the sea-bed of the Sout

There has been a long history of debate over the extent and timing of past glaciations on the small but climatically-sensitive islands of the sub-Antarctic. The largest of these islands, South Georgia, has been the focus of contention with two conflicting models proposed for the peak of the last glaciation (the Last Glacial Maximum, c. 21 k yrs B.P.): one suggesting an ice cap of restricted extent that saw tidewater outlets limited to the coastal basins of radial fjords; the other proposing an extensive shelf-wide ice cap based on well-preserved though as yet un-dated or un-sampled sea-bed geomorphology. It has been suggested that these two models form comparative end-members of 'South American‘ (restricted) and 'Antarctic‘ (extensive) modes of glaciation, and thus establishing whether the pattern of glaciation on sub- Antarctic islands follows one of these modes, or is in itself entirely different, can provide potentially important insight into past climate forcing of an otherwise poorly-constrained Southern Ocean region. The extent of island glaciation can also provide valuable far-field constraint for Antarctic ice sheet models, and forms vital information for biologists seeking to understand benthic marine communities around South Georgia, whose evolution and structure are intimately linked to the long-term history of ice advance and retreat. Here we investigate the geological record offshore of South Georgia to improve understanding of the extent and timing of past glaciation. Marine geophysical data from new and previous research cruises have been compiled and analysed to advance knowledge of palaeo-ice cap dynamics on the island‘s submerged sea bed and subsurface. We have also sought an independent verification of the glacial history of the island by linking new geomorphological analyses with dated marine sedimentary records recovered by coring, for the first time, on the continental shelf. We present results of new landform mapping on the sea-bed of the Sout

Recent studies have demonstrated significant sulfide and methane production by sewer biofilms, particularly in rising mains. Sewer sediments in gravity sewers are also biologically active; however, their contribution to biological transformations in sewers is poorly understood at present. In this study, sediments collected from a gravity sewer were cultivated in a laboratory reactor fed with real wastewater for more than one year to obtain intact sediments. Batch test results show significant sulfide production with an average rate of 9.20 ± 0.39 g S/m(2)·d from the sediments, which is significantly higher than the areal rate of sewer biofilms. In contrast, the average methane production rate is 1.56 ± 0.14 g CH4/m(2)·d at 20 °C, which is comparable to the areal rate of sewer biofilms. These results clearly show that the contributions of sewer sediments to sulfide and methane production cannot be ignored when evaluating sewer emissions. Microsensor and pore water measurements of sulfide, sulfate and methane in the sediments, microbial profiling along the depth of the sediments and mathematical modelling reveal that sulfide production takes place near the sediment surface due to the limited penetration of sulfate. In comparison, methane production occurs in a much deeper zone below the surface likely due to the better penetration of soluble organic carbon. Modelling results illustrate the dependency of sulfide and methane productions on the bulk sulfate and soluble organic carbon concentrations can be well described with half-order kinetics.

Recent studies have demonstrated significant sulfide and methane production by sewer biofilms, particularly in rising mains. Sewer sediments in gravity sewers are also biologically active; however, their contribution to biological transformations in sewers is poorly understood at present. In this study, sediments collected from a gravity sewer were cultivated in a laboratory reactor fed with real wastewater for more than one year to obtain intact sediments. Batch test results show significant sulfide production with an average rate of 9.20 ± 0.39 g S/m(2)·d from the sediments, which is significantly higher than the areal rate of sewer biofilms. In contrast, the average methane production rate is 1.56 ± 0.14 g CH4/m(2)·d at 20 °C, which is comparable to the areal rate of sewer biofilms. These results clearly show that the contributions of sewer sediments to sulfide and methane production cannot be ignored when evaluating sewer emissions. Microsensor and pore water measurements of sulfide, sulfate and methane in the sediments, microbial profiling along the depth of the sediments and mathematical modelling reveal that sulfide production takes place near the sediment surface due to the limited penetration of sulfate. In comparison, methane production occurs in a much deeper zone below the surface likely due to the better penetration of soluble organic carbon. Modelling results illustrate the dependency of sulfide and methane productions on the bulk sulfate and soluble organic carbon concentrations can be well described with half-order kinetics.

Nanostructures produced by slow highly charged ion (HCI) impact on surfaces have been a hot topic recently. In this contribution we present first investigations on the effect of individual slow HCI bombardment of freestanding carbon nano-membranes (CNMs). The CNMs are produced by cross-linking of an aromatic self-assembled monolayer of biphenyl units with lowenergy electrons [5]. The substrate is then subsequently removed and the resulting nanosheet (1 nm thickness) transferred onto a holey carbon TEM grid. CNMs produced in such a way are irradiated by slow Xeq+ ions of various charge states (20 ! q ! 40) and kinetic energies (4 keV ! E ! 180 keV). After irradiation the CNMs are inspected by high resolution imaging techniques, e.g. TEM, SEM and AFM. On the irradiated CNMs we find nanoscopic pores (3 - 30 nm in diameter, see fig. 1), whose number density corresponds well with the incident ion fluence, indicating that about every HCI produces a nano-hole in the CNM. First evaluations of the size distribution of the created pores indicate that the average diameter of a hole induced by a given ion depends strongly on the potential energy of the projectile ion, but is also influenced by the kinetic energy.

We describe the use of slow highly charged ions as a simple tool for the fabrication of nanopores with well-defined diameters typically between 10 and 20 nm in freestanding, 1 nm thick carbon nanomembranes (CNMs). When CNMs are exposed to a flux of highly charged ions, for example Xe40+, each individual ion creates a circular nanopore, the size of which depends on the kinetic and potential energy of the impinging ion. The controlled fabrication of nanopores with a uniform size opens a path for the application of CNM based filters in nanobiotechnology.

Nanostructures produced by slow highly charged ion (HCI) impact on surfaces have been a hot topic recently. In this contribution we present first investigations on the effect of individual slow HCI bombardment of freestanding carbon nano-membranes (CNMs). The CNMs are produced by cross-linking of an aromatic self-assembled monolayer of biphenyl units with lowenergy electrons [5]. The substrate is then subsequently removed and the resulting nanosheet (1 nm thickness) transferred onto a holey carbon TEM grid. CNMs produced in such a way are irradiated by slow Xeq+ ions of various charge states (20 ! q ! 40) and kinetic energies (4 keV ! E ! 180 keV). After irradiation the CNMs are inspected by high resolution imaging techniques, e.g. TEM, SEM and AFM. On the irradiated CNMs we find nanoscopic pores (3 - 30 nm in diameter, see fig. 1), whose number density corresponds well with the incident ion fluence, indicating that about every HCI produces a nano-hole in the CNM. First evaluations of the size distribution of the created pores indicate that the average diameter of a hole induced by a given ion depends strongly on the potential energy of the projectile ion, but is also influenced by the kinetic energy.

Nanostructures produced by slow highly charged ion (HCI) impact on surfaces have been a hot topic recently. In this contribution we present first investigations on the effect of individual slow HCI bombardment of freestanding carbon nano-membranes (CNMs). The CNMs are produced by cross-linking of an aromatic self-assembled monolayer of biphenyl units with lowenergy electrons [5]. The substrate is then subsequently removed and the resulting nanosheet (1 nm thickness) transferred onto a holey carbon TEM grid. CNMs produced in such a way are irradiated by slow Xeq+ ions of various charge states (20 ! q ! 40) and kinetic energies (4 keV ! E ! 180 keV). After irradiation the CNMs are inspected by high resolution imaging techniques, e.g. TEM, SEM and AFM. On the irradiated CNMs we find nanoscopic pores (3 - 30 nm in diameter, see fig. 1), whose number density corresponds well with the incident ion fluence, indicating that about every HCI produces a nano-hole in the CNM. First evaluations of the size distribution of the created pores indicate that the average diameter of a hole induced by a given ion depends strongly on the potential energy of the projectile ion, but is also influenced by the kinetic energy.

Nanostructures produced by slow highly charged ion (HCI) impact on surfaces have been a hot topic recently. In this contribution we present first investigations on the effect of individual slow HCI bombardment of freestanding carbon nano-membranes (CNMs). The CNMs are produced by cross-linking of an aromatic self-assembled monolayer of biphenyl units with lowenergy electrons [5]. The substrate is then subsequently removed and the resulting nanosheet (1 nm thickness) transferred onto a holey carbon TEM grid. CNMs produced in such a way are irradiated by slow Xeq+ ions of various charge states (20 ! q ! 40) and kinetic energies (4 keV ! E ! 180 keV). After irradiation the CNMs are inspected by high resolution imaging techniques, e.g. TEM, SEM and AFM. On the irradiated CNMs we find nanoscopic pores (3 - 30 nm in diameter, see fig. 1), whose number density corresponds well with the incident ion fluence, indicating that about every HCI produces a nano-hole in the CNM. First evaluations of the size distribution of the created pores indicate that the average diameter of a hole induced by a given ion depends strongly on the potential energy of the projectile ion, but is also influenced by the kinetic energy.

Nanostructures produced by slow highly charged ion (HCI) impact on surfaces have been a hot topic recently. In this contribution we present first investigations on the effect of individual slow HCI bombardment of freestanding carbon nano-membranes (CNMs). The CNMs are produced by cross-linking of an aromatic self-assembled monolayer of biphenyl units with lowenergy electrons [5]. The substrate is then subsequently removed and the resulting nanosheet (1 nm thickness) transferred onto a holey carbon TEM grid. CNMs produced in such a way are irradiated by slow Xeq+ ions of various charge states (20 ! q ! 40) and kinetic energies (4 keV ! E ! 180 keV). After irradiation the CNMs are inspected by high resolution imaging techniques, e.g. TEM, SEM and AFM. On the irradiated CNMs we find nanoscopic pores (3 - 30 nm in diameter, see fig. 1), whose number density corresponds well with the incident ion fluence, indicating that about every HCI produces a nano-hole in the CNM. First evaluations of the size distribution of the created pores indicate that the average diameter of a hole induced by a given ion depends strongly on the potential energy of the projectile ion, but is also influenced by the kinetic energy.

Contains fulltext : 81293.pdf (publisher's version ) (Closed access), A nonadiabatic molecular dynamics is implemented in the framework of the time-dependent density functional tight binding method (TDDFTB) combined with Tully's stochastic surface hopping algorithm. The applicability of our method to complex molecular systems is illustrated on the example of the ultrafast excited state dynamics of microsolvated adenine. Our results demonstrate that in the presence of water, upon initial excitation to the S(3) (pi-pi*) state at 260 nm, an ultrafast relaxation to the S(1) state with a time constant of 16 fs is induced, followed by the radiationless decay to the ground state with a time constant of 200 fs.

Contains fulltext : 81293.pdf (publisher's version ) (Closed access), A nonadiabatic molecular dynamics is implemented in the framework of the time-dependent density functional tight binding method (TDDFTB) combined with Tully's stochastic surface hopping algorithm. The applicability of our method to complex molecular systems is illustrated on the example of the ultrafast excited state dynamics of microsolvated adenine. Our results demonstrate that in the presence of water, upon initial excitation to the S(3) (pi-pi*) state at 260 nm, an ultrafast relaxation to the S(1) state with a time constant of 16 fs is induced, followed by the radiationless decay to the ground state with a time constant of 200 fs.

Contains fulltext : 81293.pdf (publisher's version ) (Closed access), A nonadiabatic molecular dynamics is implemented in the framework of the time-dependent density functional tight binding method (TDDFTB) combined with Tully's stochastic surface hopping algorithm. The applicability of our method to complex molecular systems is illustrated on the example of the ultrafast excited state dynamics of microsolvated adenine. Our results demonstrate that in the presence of water, upon initial excitation to the S(3) (pi-pi*) state at 260 nm, an ultrafast relaxation to the S(1) state with a time constant of 16 fs is induced, followed by the radiationless decay to the ground state with a time constant of 200 fs.

The excavator was transferred for use in the Profen lignite mine, Germany, where operations will be gradually transferred from Profen South to Schwerzau. The stripping ratio is lower and the geological conditions and coal quality are poorer at Schwerzau, necessitating a reduction in unit costs. The excavator was dismantled at the Sverma mine in the Czech Republic and components such as track carriers, conveyor gearboxes, hoisting units and track systems were reconditioned. Repairs were carried out to belt pulleys, rope winding and baffle drums. After shipment to Schwerzau a new bucket wheel and gearbox were fitted, new electrical components installed and the wheel boom extended. The machine was commissioned in April 2006., The excavator was transferred for use in the Profen lignite mine, Germany, where operations will be gradually transferred from Profen South to Schwerzau. The stripping ratio is lower and the geological conditions and coal quality are poorer at Schwerzau, necessitating a reduction in unit costs. The excavator was dismantled at the Sverma mine in the Czech Republic and components such as track carriers, conveyor gearboxes, hoisting units and track systems were reconditioned. Repairs were carried out to belt pulleys, rope winding and baffle drums. After shipment to Schwerzau a new bucket wheel and gearbox were fitted, new electrical components installed and the wheel boom extended. The machine was commissioned in April 2006.

Carbonate-free portions of Upper Cretaceous to Holocene sediment samples from the Kerguelen Plateau in the southern Indian Ocean were investigated by X-ray diffraction. Downhole variations in the content of opal-A, opal-CT, quartz, feldspar, barite, and clinoptilolite were studied at Site 737 on the northern Kerguelen Plateau and at Sites 744 and 738 on the southern Kerguelen Plateau. The variation of these components reflects temporal changes in the depositional history of the Kerguelen Plateau as well as major differences in the sedimentary evolution between the northern plateau and the southern plateau. Carbonate is the dominant component in the pelagic sediments on the Kerguelen Plateau. In addition, biogenic opal sedimentation plays an important role throughout most of the sequence. A major increase in opal accumulation is documented at all sites in late Miocene time, which is in accordance with the well-known increase in silica productivity probably caused by a major cooling step. Because of its position near the Polar Frontal Zone, sediments from Site 737 show a more extensive opal deposition than at Sites 744 and 738. An earlier productivity pulse is documented at Site 744 on the southern plateau within the early Oligocene, following the initial phase of intense East Antarctic glaciation. This cooling event resulted in higher amounts of ice-rafted terrigenous quartz and, to a lesser extent, feldspar. With the exception of the Site 744 sediments, opal deposition in Paleogene and older sediments can be reconstructed only from the diagenetic transformation products of opal-CT and probably clinoptilolite. In contrast to the southern sequence, on the northern Kerguelen Plateau higher amounts of clinoptilolite and no opal-CT were found. These major differences in the diagenetic environments may be due to extensive volcanism in the northern area. The volcanic influence at Site 737 is well recorded by the higher feldspar content and higher amounts of volcanic glass

Carbonate-free portions of Upper Cretaceous to Holocene sediment samples from the Kerguelen Plateau in the southern Indian Ocean were investigated by X-ray diffraction. Downhole variations in the content of opal-A, opal-CT, quartz, feldspar, barite, and clinoptilolite were studied at Site 737 on the northern Kerguelen Plateau and at Sites 744 and 738 on the southern Kerguelen Plateau. The variation of these components reflects temporal changes in the depositional history of the Kerguelen Plateau as well as major differences in the sedimentary evolution between the northern plateau and the southern plateau. Carbonate is the dominant component in the pelagic sediments on the Kerguelen Plateau. In addition, biogenic opal sedimentation plays an important role throughout most of the sequence. A major increase in opal accumulation is documented at all sites in late Miocene time, which is in accordance with the well-known increase in silica productivity probably caused by a major cooling step. Because of its position near the Polar Frontal Zone, sediments from Site 737 show a more extensive opal deposition than at Sites 744 and 738. An earlier productivity pulse is documented at Site 744 on the southern plateau within the early Oligocene, following the initial phase of intense East Antarctic glaciation. This cooling event resulted in higher amounts of ice-rafted terrigenous quartz and, to a lesser extent, feldspar. With the exception of the Site 744 sediments, opal deposition in Paleogene and older sediments can be reconstructed only from the diagenetic transformation products of opal-CT and probably clinoptilolite. In contrast to the southern sequence, on the northern Kerguelen Plateau higher amounts of clinoptilolite and no opal-CT were found. These major differences in the diagenetic environments may be due to extensive volcanism in the northern area. The volcanic influence at Site 737 is well recorded by the higher feldspar content and higher amounts of volcanic glass

Carbonate-free portions of Upper Cretaceous to Holocene sediment samples from the Kerguelen Plateau in the southern Indian Ocean were investigated by X-ray diffraction. Downhole variations in the content of opal-A, opal-CT, quartz, feldspar, barite, and clinoptilolite were studied at Site 737 on the northern Kerguelen Plateau and at Sites 744 and 738 on the southern Kerguelen Plateau. The variation of these components reflects temporal changes in the depositional history of the Kerguelen Plateau as well as major differences in the sedimentary evolution between the northern plateau and the southern plateau. Carbonate is the dominant component in the pelagic sediments on the Kerguelen Plateau. In addition, biogenic opal sedimentation plays an important role throughout most of the sequence. A major increase in opal accumulation is documented at all sites in late Miocene time, which is in accordance with the well-known increase in silica productivity probably caused by a major cooling step. Because of its position near the Polar Frontal Zone, sediments from Site 737 show a more extensive opal deposition than at Sites 744 and 738. An earlier productivity pulse is documented at Site 744 on the southern plateau within the early Oligocene, following the initial phase of intense East Antarctic glaciation. This cooling event resulted in higher amounts of ice-rafted terrigenous quartz and, to a lesser extent, feldspar. With the exception of the Site 744 sediments, opal deposition in Paleogene and older sediments can be reconstructed only from the diagenetic transformation products of opal-CT and probably clinoptilolite. In contrast to the southern sequence, on the northern Kerguelen Plateau higher amounts of clinoptilolite and no opal-CT were found. These major differences in the diagenetic environments may be due to extensive volcanism in the northern area. The volcanic influence at Site 737 is well recorded by the higher feldspar content and higher amounts of volcanic glass