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A star sensor for measuring small pointing errors in astronomical telescopes is described. By using solid state imaging arrays (CCDs) to track guide star images, this design realizes a number of performance advantages relative to more conventional approaches. Specific topics include star image position measurement, CCD sensitivity including color effects, and performance simulation results. Experimental results for CCDs operating at temperatures below 100 K are also summarized. Two telescope configurations are considered to illustrate the range of possible applications of this technology: (1) a large orbiting telescope for general astronomy requiring a multi-CCD sensor, and (2) a Space Shuttle-based infrared observatory operating at 20 K. Although the requirements and configurations of these applications are widely different, the CCD approach offers substantial advantages to both systems.

13C and 2H NMR spectroscopy has been employed to probe the biosynthesis of vitamin B6 in Escherichia coli. The 13C NMR spectrum of a sample of pyridoxol derived biosynthetically from D-[1,2,3,4,5,6-13C6]glucose shows that the bonds, C(2)-C(3) and C(4)-C(5), of the pyridine nucleus are the only two carbon-carbon bonds of pyridoxol which are generated de novo in the course of its biosynthesis from glucose. It follows that the pyridoxol skeleton is generated from two intact triose units and a triose-derived two-carbon unit, all of which are supplied by glucose. From the 2H NMR spectra of samples of pyridoxol derived from (R)-[1,1-2H2]glycerol and (S)-[1,1-2H2]glycerol, respectively, it can be deduced that the rehydroxymethyl group of glycerol enters C-2', C-4', and C-5' of the pyridoxol skeleton. It follows that each of the three fragments is derived from glycerol in stereo-specific fashion. These results answer questions concerning the regiochemistry and the stereochemistry of pyridoxol biosynthesis.

Liver poly(A) RNA, isolated from adrenalectomized rats after insulin treatment, was translated in a nuclease-treated lysate of rabbit reticulocytes and quantitated for both total activity and the capacity to synthesize the insulin-inducible enzyme tyrosine aminotransferase. Analysis of the translated products from poly(A) RNA isolated 1 h after insulin treatment showed a 2.7-fold increase in activity of tyrosine aminotransferase mRNA. During the same interval, the capacity of poly(A) RNA to direct the synthesis of total protein in lysates also changed, showing a 30 to 40% increase in translational activity/unit of RNA. Increased translatability was apparent in all fractions of poly(A) RNA separated by centrifugation on sucrose gradients. Insulin thus appears to mediate a generalized change in mRNAs leading to increased capacity for translation; induction of tyrosine aminotransferase may reflect sensitivity to effect of the hormone.

Sorbitol was the sole cause of protracted diarrhoea in seven children seen in two paediatric-gastroenterology outpatient departments. The sorbitol had been administered in the form of a vitamin C supplement in all seven children. Pink staining of napkins was a prominent feature in five of these seven patients, and was attributed to the cochineal dye contained in the vitamin C supplement. In children with chronic or intermittent watery diarrhoea, a careful dietary history should be obtained. If sorbitol ingestion is documented, a trial of sorbitol exclusion is recommended before embarking on extensive investigations.

Competition experiments, employing 14C-labeled samples of glycerol and glycolaldehyde, indicate that in Escherichia coli B there are two independent pathways leading to pyridoxal. In mutant WG2 (and therefore presumably also in the wild strain) the major pathway utilizes glycerol and related trioses as the sole carbon source in the construction of the C8N skeleton of pyridoxol: C-1, -3 of glycerol yields C-2', -3, -4', -5' and -6, C-2 of glycerol yields C-2, -4, and -5 of the vitamin. In the minor pathway glycolaldehyde and not glycerol supplies C-5 and C-5' of pyridoxol, while glycerol is the source of the other 6 carbon atoms. In mutant WG3 the major route is blocked and the "glycolaldehyde pathway" becomes the sole source of vitamin B6.

Fat absorption was assessed on two or more occasions in 12 of 14 patients with Shwachman syndrome. Of 11 children who initially had steatorrhea, 6 were subsequently found to have normal fat excretion. In 10 of these 11 patients the last estimate was smaller than the initial estimate after an interval of 0.3-12.7 yr. The most dramatic improvement occurred under 4 yr of age but improvement appeared to continue over a more extended period where sufficient follow-up was available. All patients had pronounced pancreatic insufficiency as tested by duodenal drainage corrected by nonabsorbable marker under stimulation with cholecystokinin and secretin. Pancreatic lipase secretion was assessed in 3 patients with steatorrhea and 5 without steatorrhea (73% of the surviving patients) using a sensitive assay which used maximum stimulation with colipase. Pancreatic lipase secretion was less than 2% of normal mean secretion in the steatorrheic patients and ranged from 3.7% to 13.6% in the patients without steatorrhea. These results indicate that fat absorption improves in the majority of patients with Shwachman syndrome and appears to be associated with marginal improvement in pancreatic lipase secretion. Due to the occult nature of bowel complaints in older patients, the diagnosis may be overlooked unless careful screening for pancreatic function takes place.

Sorbitol was the sole cause of protracted diarrhoea in seven children seen in two paediatric-gastroenterology outpatient departments. The sorbitol had been administered in the form of a vitamin C supplement in all seven children. Pink staining of napkins was a prominent feature in five of these seven patients, and was attributed to the cochineal dye contained in the vitamin C supplement. In children with chronic or intermittent watery diarrhoea, a careful dietary history should be obtained. If sorbitol ingestion is documented, a trial of sorbitol exclusion is recommended before embarking on extensive investigations.

The Los Alamos Meson Physics Facility (LAMPF) operated with simultaneous H+ and H- beams until June 1980, when a method of providing a variable energy H- beam as well as a full-energy H+ beam was brought into use. The scheme is based on time sharing between H+ and H- beam pulses. It is now possible to provide H- beams with energy as low as 300 MeV along with the usual 800-MeV H+ beams. The method requires a reduction in duty factor of the H+ and H- beams; however, the total duty factor has been increased to 9% which compensates in large measure for the reduction due to dual-energy operation. The necessary modifications to the beam switchyard and accelerator timing systems are described.

The acoustic pressures produced by a band of noise were measured at the entrance to the auditory canal and near the tympanum. The stimuli was produced by a TDH‐39 earphone activated by a noise band tailored to produce an approximately flat spectrum between 0.1 and about 4 kHz at the entrance to the ear canal. A computer program calculated the output power spectra, the signal/noise, the cross‐power spectrum, the transfer function, the coherence function, and the phase between the input and output power spectra. The transfer function in each animal shows an upper frequency peak, the location of which varies with the apparent volume of the canal, being highest for the guinea pig and lowest for man. The magnitude of the resonance is largest for the cat and smallest for the guinea pig. [Supported in part by DAMD 17‐78C‐8067 and NSF‐77‐16907.]

Photometric observations are presented for outbursts of the quasi-stellar object QSO 1156+295 in 1981 and 1982. High time resolution photometry is included showing variations on time scales of weeks to about half an hour. Data from early plate material show that the object may have been quite bright at the beginning of this century but was quite faint and probably inactive between about 1950 and the beginning of recent activity in 1977-1979. Some results of optical linear polarization are discussed. In examining spectrophotometric results, broadband spectra show very little change in spectral shape during changes in continuum brightness. High resolution spectra (0.1-A FWHM) show no evidence for the Mg II 2798-A absorption sometimes seen in optically violent variables and other QSOs. The radio flux density variations at several frequencies are documented and discussed and compared with the optical light curve. Models for 1156+295 are discussed including variability time scales, and the observed energy output is compared with a magnetic accretion disk model proposed by Shields and Wheeler (1976). Results are summarized and the different sizes of active and inactive regions of the object are compared.

High‐intensity, low‐frequency octave band noise in the free field has been reported to produce permanent threshold shift at 2 kHz in chinchillas [Burdick, Patterson, Mozo, and Camp, J. Acoust. Soc. Am. 64, 458 (1978)]. We have delivered 100‐ and 250‐Hz low‐pass noise to the chinchilla with intact pinna but open bulla and have measured the spectrum of the CM recorded with electrodes in turn I and turn II. SPL's were measured at the pinna. The output of the microphone was led to channel 1 of an A/D converter. The CM was led to channel 2. The inputs to the A/D's were adjusted to the same rms level to minimize digital noise. A computer program calculated FFT's and produced several calculations from them (see previous abstract). At SPL's below 100 dB, the output spectrum (CM) is similar to the input spectrum (microphone). Above 100 dB the output spectrum contains frequencies above the passband of the input spectrum. The coherence function indicates that the high‐frequency output is not present in the input power spectrum. [Supported in part by DAMD17‐78C‐8067 and NSF 77‐16907.]