Surface and Tethered-Balloon Observations of Actinic Flux: Effects of Arctic stratus, Surface Albedo and Solar Zenith Angle

As part of the FIRE III (First ISCCP Regional Experiment) Arctic Cloud Experiment actinic flux measurements were made above the Arctic Sea ice during May 1998. FIRE III was designed to address questions concerning clouds, radiation and chemistry in the Arctic sea ice region. The actinic flux, which is also referred to as the 4p-radiative flux, is the relevant radiative parameter needed to determine photodissociation rates. Moreover, it is discussed that the actinic flux may be used to determine vertical absorption profiles of the net irradiance, provided that the single scattering albedo is known. The diurnal cycle of UV-A (wavelength about 365 nm) and visible (wavelength about 550 nm) actinic fluxes during clear and cloudy conditions was measured by two 4p- radiometers installed just above the ice surface. In addition, vertical profiles of the visible actinic flux through low arctic stratus clouds were observed by means of a tethered balloon. The cloud thermodynamic and microphysical structure was assessed from observations made by the NCAR C-130 aircraft. The liquid water path was retrieved by a microwave radiometer. During clear skies the diurnal variation of the actinic flux was controlled mainly by Rayleigh scattering. Above the cloud layer the actinic flux was found to be almost the same as during clear sky conditions. This could be attributed to the fact that the effective albedo of the arctic sea ice and the cloud is only slightly higher than the ground albedo alone. The observed vertical actinic flux profiles in arctic stratus are discussed and compared with similar measurements made in Atlantic stratocumulus. In the arctic stratus clouds the actinic flux was found to be nearly constant with height, except in a shallow layer near the cloud top where the actinic flux significantly increased with height. The role of the solar zenith angle and ground albedo on in-cloud actinic flux profiles is discussed. It is concluded that the observed strong increase of the actinic flux in the upper part of the arctic stratus layer is a typical feature associated with large solar zenith angles

Bone Mineral Density in Adult Survivors of Pediatric Differentiated Thyroid Carcinoma:A Longitudinal Follow-Up Study

Background: Survivors of pediatric differentiated thyroid carcinoma (DTC) receive thyrotropin-suppressive therapy to minimize disease recurrence. However, knowledge about long-term effects of subclinical hyperthyroidism on bone mineral density (BMD) in pediatric DTC survivors is scarce, as is the information regarding long-term consequences of permanent hypoparathyroidism on BMD. We evaluated BMD in pediatric DTC survivors and investigated if BMD was affected by subclinical hyperthyroidism and/or permanent hypoparathyroidism during long-term follow-up. Methods: In this nationwide longitudinal study, we determined BMD in the lumbar spine and femur by dual energy X-ray absorptiometry in 65 pediatric DTC survivors. Measurements were repeated after minimal 5 years of follow-up in 46 pediatric DTC survivors. BMD results were evaluated according to the recommendations of the International Society for Clinical Densitometry (ISCD) and WHO. At both visits, we determined biochemical parameters and markers of bone resorption (C-terminal telopeptide of type I collagen [β-CTX]) and formation (N-propeptide of type I collagen [PINP] and osteocalcin). Results: First and second BMD measurements were done after a median follow-up of 17.0 (interquartile range [IQR] 8.0-25.0) and 23.5 (IQR 14.0-30.0) years after diagnosis, respectively. Median age at diagnosis was 15 years (IQR 13.0-17.0). Twenty-nine percent of the survivors had subclinical hyperthyroidism. In most survivors, BMD T-and Z-scores were within the reference range during both BMD evaluations. However, after 23.5 years of follow-up, a low BMD was found in 13.0%. In the 13 survivors with permanent hypoparathyroidism, BMD values did not differ after 5 years of follow-up compared with baseline values or in comparison with the 33 survivors without permanent hypoparathyroidism. During follow-up, turnover markers β-CTX and PINP remained stable. Conclusions: This longitudinal study of pediatric DTC survivors demonstrated normal and stable median lumbar spine and femur BMD values after a median time of 17 and 23.5 years after diagnosis. However, compared with controls, a lower BMD was still found in 13.0% after prolonged follow-up despite intensive follow-up. Based on the studied follow-up period, these data do not provide convincing evidence in support of standard monitoring of bone mass among DTC survivors, but may be restricted to individual cases at low frequency. Trial Registration: This follow-up study was registered in The Netherlands Trial Register under no. NL3280 (www.trialregister.nl/trial/3280)

Why Do Borrowers Pledge Collateral? New Empirical Evidence on the Role of Asymmetric Information

An important theoretical literature motivates collateral as a mechanism that mitigates adverse selection, credit rationing, and other inefficiencies that arise when borrowers hold ex ante private information. There is no clear empirical evidence regarding the central implication of this literature - that a reduction in asymmetric information reduces the incidence of collateral. We exploit exogenous variation in lender information related to the adoption of an information technology that reduces ex ante private information, and compare collateral outcomes before and after adoption. Our results are consistent with this central implication of the private-information models and support the empirical importance of this theory

Een Regenjasje Voor het Aapje: Een Integrale Vertaling van Bashō's Sarumino

Dit boek is een integrale vertaling in het Nederlands van de bundel Sarumino. Zij omvat niet alleen de gedichten van Bashō zelf, maar ook die van zijn vele discipelen, en niet alleen de haiku, maar ook de kettinggedichten (renga) en het prozastuk over Bashō’s tijdelijke verblijf Genjūan. De vertaling is voorzien van een uitgebreide annotatie en voor- en nawoorden