ABSTRACT
We measured the Newtonian constant of gravity, G, using a gravity gradiometer based on atom interferometry. The gradiometer measures the differential acceleration of two samples of laser-cooled Cs atoms. The change in gravitational field along one dimension is measured when a well-characterized Pb mass is displaced. Here, we report a value of G = 6.693 x 10(-11) cubic meters per kilogram second squared, with a standard error of the mean of +/-0.027 x 10(-11) and a systematic error of +/-0.021 x 10(-11) cubic meters per kilogram second squared. The possibility that unknown systematic errors still exist in traditional measurements makes it important to measure G with independent methods.
ABSTRACT
We present a method of analysis involving ellipse-specific fitting of sinusoidally coupled data from two gravimeters in a gradiometer configuration. This method permits rapid extraction of induced gradient phase shifts in the presence of common-mode vibrational phase noise. Gravity gradients can be accurately measured in the presence of large vibrational accelerations.
ABSTRACT
Diamond-Blackfan Anemia (DBA) is a rare, congenital hypoplastic anemia often diagnosed early in infancy. A moderate to severe aregenerative anemia is found in association with erythroblastopenia in an otherwise normocellular bone marrow. In 40% of these infants with DBA, diverse developmental abnormalities are also noted. A majority of patients with DBA respond to steroid therapy. Recent molecular studies have identified mutations in the gene encoding the ribosomal protein RPS19 on chromosome 19 in 25% of patients with DBA. In another subset of patients, linkage analysis has identified another locus on chromosome 8p in association with DBA. There are, however, other cases of DBA that are linked neither to the RPS19 gene nor to the locus on 8p, implying the involvement of yet-to-be-defined genetic defects in the cause of DBA. The pathogenesis of DBA is still to be fully defined and it is anticipated that further molecular studies will lead to a better understanding of this complex disease.
Subject(s)
Fanconi Anemia , Abnormalities, Multiple , Child, Preschool , Chromosomes, Human, Pair 19/genetics , Chromosomes, Human, Pair 8/genetics , Failure to Thrive , Fanconi Anemia/diagnosis , Fanconi Anemia/epidemiology , Fanconi Anemia/genetics , Fanconi Anemia/physiopathology , Genetic Heterogeneity , Humans , Infant , MutationABSTRACT
We have demonstrated a new technique for detecting ultracold atoms. A balanced detection technique was used to reduce laser-induced detection noise in conjunction with modulation-transfer spectroscopy to distinguish cold atoms from a thermal cloud. Using this technique, we have achieved signal-to-noise ratios in excess of 2000:1.
ABSTRACT
Since the genetic basis of sickle cell anemia was discovered over 50 years ago, many therapies have been developed for the treatment of this disorder. Hematopoietic cell transplantation offers curative potential, but it is associated with a 5-10% risk of dying. Patients who undergo allografting but develop stable donor-host hematopoietic chimerism appear to experience a significant clinical benefit. Our paper discusses the risks and benefits of hematopoietic cell transplantation in patients with sickle cell disease and summarizes the outcome of 147 patients who received allografts for sickle cell disease. We also review the development of new approaches to establish stable mixed chimerism after transplantation for sickle cell disease.
