Stabilizing Lead-Salt Diode Lasers: Understanding and Controlling Chaotic Frequency Emission     

G Chin  LR Senesac  WE Blass  JJ Hillman 《Science (New York, N.Y.)》1996,274(5292):1498-1501

Lead-salt tunable diode lasers (TDLs) are the only devices currently available that can generate tunable monochromatic radiation at arbitrary wavelengths between 3 and 30 micrometers and are particularly useful for high-resolution spectroscopy over a wide range of spectral regimes. Detailed observations of TDLs show that the observed instrumental linewidth is actually a temporal average of many narrow (less than 0.5 megahertz) emission "modes." The time scale characteristic of these "modes," which appear to be of relatively constant intensity, is of the order of a microsecond. The laser's behavior is highly suggestive of a chaotic process, that is, seemingly random excursions of a dynamic variable (frequency) within a bounded range. This report shows experimentally that TDL emissions are indeed chaotic. Furthermore, in a simple and robust fashion, this chaotic behavior has been successfully controlled with the use of recent techniques that take advantage of chaos to produce a narrow band laser output.  相似文献   

Determination of thermal histories of archeological cereal grains with electron spin resonance spectroscopy     

Hillman GC  Robins GV  Oduwole D  Sales KD  McNeil DA 《Science (New York, N.Y.)》1983,222(4629):1235-1236

The thermal histories of archeological cereal grains were examined by electron spin resonance spectroscopy. Studies with modern samples of heated cereal grain showed that the parameters of the electron spin resonance signal characterize the maximum temperature to which the sample had previously been heated. This technique has applicability in archeology and other disciplines.  相似文献   

Calibrating duckweeds: light, clocks, metabolism, flowering     

Hillman WS 《Science (New York, N.Y.)》1976,193(4252):453-458

The roles of photoperiodism and related light-dependent and hormonal processes in plants are not well understood. Rapid growth, aquatic habit, and adaptability to axenic culture make the Lemnaceae, or duckweeds, excellent material for investigating these topics and others in which highly defined conditions or the presence of organic substances are crucial. As a major example among several that are described, recent work with one species suggests a relation between some features of carbon dioxide flux and the photoperiodic timing mechanism, thus providing a system in which the biochemical basis of the latter may be explored.  相似文献   

Bilateral cataract surgery in a Suffolk ewe     

H H Oz  R J McClure  D J Hillman 《The Veterinary record》1986,118(18):512-513

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Prevalence of koala retrovirus in geographically diverse populations in Australia     

GS Simmons  PR Young  JJ Hanger  K Jones  D Clarke  JJ McKee  J Meers 《Australian veterinary journal》2012,90(10):404-409

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Extent of utilisation of dual‐purpose wheat for grazing by late‐pregnant and lambing ewes and producer‐reported incidence of health issues in southern New South Wales     

SR McGrath  JJ Lievaart  MA Friend 《Australian veterinary journal》2013,91(10):432-436

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Incidence of calf scours and associated risk factors in southern New South Wales beef herds     

JJ Lievaart  NR Charman  C Scrivener  A Morton  MB Allworth 《Australian veterinary journal》2013,91(11):464-468

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Mucopolysaccharidosis type VI in a Miniature Poodle-type dog caused by a deletion in the arylsulphatase B gene     

RD Jolly  JJ Hopwood  NR Marshall  KS Jenkins  DJ Thompson  KE Dittmer 《New Zealand veterinary journal》2013,61(3):183-188

Abstract

AIM: To investigate and characterise an inborn error of metabolism in a dog with skeletal and ocular abnormalities.

METHODS: A 2.5-year-old small male Miniature Poodle-like dog was presented with gross joint laxity and bilateral corneal opacities. Clinical examination was augmented by routine haematology, serum chemistry, radiographs, pathology, enzymology and molecular genetic studies. Euthanasia was requested when the dog was 3 years of age because of progressively decreasing quality of life.

RESULTS: Radiology revealed generalised epiphyseal dysplasia, malformed vertebral bodies, luxation/subluxation of appendicular and lumbosacral joints with hypoplasia of the odontoid process and hyoid apparatus. These clinical and radiographic findings, together with a positive urinary Berry spot test for mucopolysaccharides, and metachromatic granules in leucocytes, were indicative of a mucopolysaccharidosis (MPS), a lysosomal storage disease. Histological lesions included vacuolation of stromal cells of the cornea, fibroblasts, chondrocytes, macrophages and renal cells. The brain was essentially normal except for moderate secondary Wallerian-type degeneration in motor and sensory tracts of the hind brain. Dermatan sulphate-uria was present and enzymology revealed negligible activity of N-acetylgalactosamine-4-sulphatase, also known as arylsulphatase B, in cultured fibroblasts and liver tissue. A novel homozygous 22 base pair (bp) deletion in exon 1 of this enzyme's gene was identified (c.103_124del), which caused aframe-shift and subsequent premature stop codon. The “Wisdom pure breed-mixed breed” test reported the dog as a cross between a Miniature and Toy Poodle.

CONCLUSIONS: The clinicopathological features are similar to those of MPS type VI as previously described in dogs, cats and other species, and this clinical diagnosis was confirmed by enzymology and molecular genetic studies. This is an autosomal recessively inherited lysosomal storage disease.

CLINICAL RELEVANCE: The prevalence of MPS VI in Miniature or Toy Poodles in New Zealand and elsewhere is currently unknown. Due to the congenital nature of the disorder, malformed pups may be subject to euthanasia without investigation and the potential genetic problem in the breed may not be fully recognised. The establishment of a molecular genetic test now permits screening for this mutation as a basis to an informed breeding policy.  相似文献   

Estriolum Treatment in the Bitch: A Risk for Uterine Infection?     

BA Schotanus  J de Gier  JJ van der Lugt  AC Okkens 《Reproduction in domestic animals》2008,43(2):176-180

Purulent vaginal discharge in a bitch in which ovariohysterectomy has been performed is often caused by inflammation of the uterine stump. The inflammation is due to either cystic endometrial hyperplasia (CEH) induced primarily by progesterone from remnant ovarian tissue or exogenous progestagens, or it is due to the presence of unabsorbed suture material. This report describes a 9-year-old Irish setter with hemopurulent vaginal discharge and non-pruritic symmetrical alopecia, which had undergone ovariohysterectomy 3.5 years ago and which had been treated with estriolum daily for the past 2.5 years because of urinary incontinence. Vaginoscopy revealed hemopurulent discharge throughout the vagina and vestibule. Cytological examination of ultrasound-guided fine-needle aspiration biopsies of a large mass in the hypogastricum, which appeared to be the uterine cervical stump, revealed septic purulent inflammation. The concentration of plasma progesterone was low and the concentration of plasma 17-ß oestradiol did not increase after gonadotrophin-releasing hormone administration. No remnant ovarian tissue was found by abdominal ultrasonography, laparotomy, or histological examination of mesovarian pedicles. Laparotomy revealed uterine stump empyema. Histological examination of the surgically removed mass excluded both CEH and unabsorbed suture material as the cause of the stump empyema. Instead, it is hypothesized that the long-term treatment with estriolum was a causative factor. This suggests that bitches treated with estriolum should be examined regularly.  相似文献   

Dangling bond dynamics on the silicon (100)-2x1 surface: dissociation, diffusion, and recombination     

M McEllistrem  M Allgeier  JJ Boland 《Science (New York, N.Y.)》1998,279(5350):545-548

The dynamics of dangling bond (DB) diffusion was studied after deuterium desorption from the silicon (100)-2x1 surface. At elevated temperatures, paired DB sites produced after desorption unpaired as deuterium atoms hopped from adjacent dimers. Below 620 kelvin, the unpaired configuration most commonly observed corresponded to two DBs on adjacent silicon dimers. At higher temperatures, unpaired DBs executed one-dimensional walks along the dimer rows, and recombination was observed with the same partner after walks lasting many minutes. The frequency and extent of these excursions increased with temperature. Above 660 kelvin, complete dissociation was observed and was sometimes followed by recombination by means of partner exchange. The implications for low-temperature materials growth are discussed.  相似文献