A galaxy rapidly forming stars 700 million years after the Big Bang at redshift 7.51.

Of several dozen galaxies observed spectroscopically that are candidates for having a redshift (z) in excess of seven, only five have had their redshifts confirmed via Lyman α emission, at z = 7.008, 7.045, 7.109, 7.213 and 7.215 (refs 1-4). The small fraction of confirmed galaxies may indicate that the neutral fraction in the intergalactic medium rises quickly at z > 6.5, given that Lyman α is resonantly scattered by neutral gas. The small samples and limited depth of previous observations, however, makes these conclusions tentative. Here we report a deep near-infrared spectroscopic survey of 43 photometrically-selected galaxies with z > 6.5. We detect a near-infrared emission line from only a single galaxy, confirming that some process is making Lyman α difficult to detect. The detected emission line at a wavelength of 1.0343 micrometres is likely to be Lyman α emission, placing this galaxy at a redshift z = 7.51, an epoch 700 million years after the Big Bang. This galaxy's colours are consistent with significant metal content, implying that galaxies become enriched rapidly. We calculate a surprisingly high star-formation rate of about 330 solar masses per year, which is more than a factor of 100 greater than that seen in the Milky Way. Such a galaxy is unexpected in a survey of our size, suggesting that the early Universe may harbour a larger number of intense sites of star formation than expected.

An almost head-on collision as the origin of two off-centre rings in the Andromeda galaxy.

The unusual morphology of the Andromeda galaxy (Messier 31, the closest spiral galaxy to the Milky Way) has long been an enigma. Although regarded for decades as showing little evidence of a violent history, M31 has a well-known outer ring of star formation at a radius of ten kiloparsecs whose centre is offset from the galaxy nucleus. In addition, the outer galaxy disk is warped, as seen at both optical and radio wavelengths. The halo contains numerous loops and ripples. Here we report the presence of a second, inner dust ring with projected dimensions of 1.5 x 1 kiloparsecs and offset by about half a kiloparsec from the centre of the galaxy (based upon an analysis of previously-obtained data). The two rings appear to be density waves propagating in the disk. Numerical simulations indicate that both rings result from a companion galaxy plunging through the centre of the disk of M31. The most likely interloper is M32. Head-on collisions between galaxies are rare, but it appears nonetheless that one took place 210 million years ago in our Local Group of galaxies.

Multiwavelength Light Curves of Two Remarkable Sagittarius A* Flares.

Sgr A*, the supermassive black hole (SMBH) at the center of our Milky Way Galaxy, is known to be a variable source of X-ray, near-infrared (NIR), and submillimeter radiation and therefore a prime candidate to study the electromagnetic radiation generated by mass accretion flow onto a black hole and/or a related jet. Disentangling the power source and emission mechanisms of this variability is a central challenge to our understanding of accretion flows around SMBHs. Simultaneous multiwavelength observations of the flux variations and their time correlations can play an important role in obtaining a better understanding of possible emission mechanisms and their origin. This paper presents observations of two flares that both apparently violate the previously established patterns in the relative timing of submillimeter/NIR/X-ray flares from Sgr A*. One of these events provides the first evidence of coeval structure between NIR and submillimeter flux increases, while the second event is the first example of the sequence of submillimeter/X-ray/NIR flux increases all occurring within ~1 hr. Each of these two events appears to upend assumptions that have been the basis of some analytic models of flaring in Sgr A*. However, it cannot be ruled out that these events, even though unusual, were just coincidental. These observations demonstrate that we do not fully understand the origin of the multiwavelength variability of Sgr A* and show that there is a continued and important need for long-term, coordinated, and precise multiwavelength observations of Sgr A* to characterize the full range of variability behavior.

Simultaneous X-Ray and Infrared Observations of Sagittarius A*'s Variability.

Emission from Saggitarius A* is highly variable at both X-ray and infrared (IR) wavelengths. Observations over the last ~20 yr have revealed X-ray flares that rise above a quiescent thermal background about once per day, while faint X-ray flares from Sgr A* are undetectable below the constant thermal emission. In contrast, the IR emission of Sgr A* is observed to be continuously variable. Recently, simultaneous observations have indicated a rise in IR flux density around the same time as every distinct X-ray flare, while the opposite is not always true (peaks in the IR emission may not be coincident with an X-ray flare). Characterizing the behavior of these simultaneous X-ray/IR events and measuring any time lag between them can constrain models of Sgr A*'s accretion flow and the flare emission mechanism. Using 100+ hours of data from a coordinated campaign between the Spitzer Space Telescope and the Chandra X-ray Observatory, we present results of the longest simultaneous IR and X-ray observations of Sgr A* taken to date. The cross-correlation between the IR and X-ray light curves in this unprecedented data set, which includes four modest X-ray/IR flares, indicates that flaring in the X-ray may lead the IR by approximately 10-20 min with 68% confidence. However, the 99.7% confidence interval on the time-lag also includes zero, i.e., the flaring remains statistically consistent with simultaneity. Long-duration and simultaneous multi-wavelength observations of additional bright flares will improve our ability to constrain the flare timing characteristics and emission mechanisms, and must be a priority for Galactic Center observing campaigns.

Variability Timescale and Spectral Index of Sgr A* in the Near Infrared: Approximate Bayesian Computation Analysis of the Variability of the Closest Supermassive Black Hole.

Sagittarius A* (Sgr A*) is the variable radio, near-infrared (NIR), and X-ray source associated with accretion onto the Galactic center black hole. We present an analysis of the most comprehensive NIR variability data set of Sgr A* to date: eight 24 hr epochs of continuous monitoring of Sgr A* at 4.5 µm with the IRAC instrument on the Spitzer Space Telescope, 93 epochs of 2.18 µm data from Naos Conica at the Very Large Telescope, and 30 epochs of 2.12 µm data from the NIRC2 camera at the Keck Observatory, in total 94,929 measurements. A new approximate Bayesian computation method for fitting the first-order structure function extracts information beyond current fast Fourier transformation (FFT) methods of power spectral density (PSD) estimation. With a combined fit of the data of all three observatories, the characteristic coherence timescale of Sgr A* is τ b = 243 - 57 + 82 minutes (90% credible interval). The PSD has no detectable features on timescales down to 8.5 minutes (95% credible level), which is the ISCO orbital frequency for a dimensionless spin parameter a = 0.92. One light curve measured simultaneously at 2.12 and 4.5 µm during a low flux-density phase gave a spectral index α s = 1.6 ± 0.1 ( F ν ∝ ν - α s ) . This value implies that the Sgr A* NIR color becomes bluer during higher flux-density phases. The probability densities of flux densities of the combined data sets are best fit by log-normal distributions. Based on these distributions, the Sgr A* spectral energy distribution is consistent with synchrotron radiation from a non-thermal electron population from below 20 GHz through the NIR.

Kinematic analysis of spinal fusions.

Two cases with clinical suspicion of incompletely healed anterior fusion between L5 and S1 were examined by means of a roentgen stereophotogrammetric method. In both cases a pseudarthrosis was found. The method makes it possible to disclose rotations and translations between veretebrae with an accuracy of about 0.2degree and 30-120 mum, respectively.

Airborne ultrasound applied to anthropometry--physical and technical principles.

Airborne ultrasound has been utilized for remote measurement of distance, direction, size, form, volume and velocity. General anthropometrical measurements are performed with a newly constructed real-time linear array scanner. To make full use of the method, we expect a rapid development of high-frequency ultrasound transducers for use in air.

Two-dimensional airborne ultrasound real-time linear array scanner--applied to screening for scoliosis.

Diagnostic ultrasound is an established, noninvasive and harmless method for imaging the shape and appearance of organs and other tissues inside the body, and it has been used in many clinical applications for more than three decades. We have now applied some of this well-known technique together with the use of airborne ultrasound in medical applications, to build an equipment for anthropometrical investigation outside the body, e.g., measuring and registration of the shape and form of the human back. This is mostly done for screening purposes of young people in an attempt to find patients developing scoliosis, and in order to circumvent some of the disadvantages with the traditional screening method in this field of medical application.

Prevalence study of trunk asymmetries and structural scoliosis in 10-year-old school children.

The prevalence of trunk asymmetries was studied in 6464, 10-year-old, school children in Malmö City. All those with visible trunk asymmetries were moiré photographed and a subset roentgenographed. Moiré, positive findings were seen in 13% of the boys and in 16% of the girls. A more prominent moiré asymmetry (a deviation of two moire contour lines or more) was seen in 0.6% of the boys and 0.9% of the girls. The Cobb angles in this latter group varied between 14-25 degrees. Children with small clinical and moiré asymmetries (deviations of less than one moiré fringe) had no or very small (less than 10 degrees), lateral deviations seen on the x-ray and should, therefore, be regarded rather as normal variations of the shape of the trunk. On the other hand, these small asymmetries cannot be disregarded as possible indications of a risk group in which structural scoliosis can develop later during the period of growth.

The natural history of idiopathic scoliosis. A study of the incidence of treatment.

The natural history of idiopathic scoliosis has been studied between 1969 and 1985 in a well-controlled population of school children, 66,200 cases, between 7 and 16 years of age. The incidence of scoliosis needing treatment (25 degrees or more in progress in growing children) was studied with a cross-sectional as well as a longitudinal survey. When using a cross-sectional technique, a decrease of cases being treated was seen after the introduction of a conventional screening program--thus indicating a change in the natural history of moderate scoliosis. This could, however, be explained by the consequence of an accumulation of treated cases, formerly diagnosed and treated later on, seen immediately after the introduction of screening. When the longitudinal method was used, this trend could not be observed. And finally, when taking changes of indication of treatment and of the population into consideration, no tendency at all toward a change in the natural history could be seen.

End vertebra angle--a roentgenographic method to describe a scoliosis. A follow-up study of idiopathic scoliosis treated with the Boston brace.

A new method of measuring the range of the lateral deviation of a scoliosis is introduced. Here the Cobb angle is divided into two separate parts, consisting of the angles between each end vertebra and the horizontal plane. This angle is called the end vertebra angle. One hundred and twenty-one patients with adolescent idiopathic scoliosis, treated with Boston braces, were measured according to this technique and these angles were compared with the Cobb angles. All patients had S-shaped, right convex thoracic and left convex lumbar scolioses. Three end vertebra angles were measured and called A, B, and C. The middle end vertebra angle (B) was responsible for the improvement of the scoliosis in the brace, measured according to Cobb, and also the remaining improvement 2 years after weaning from the brace. The proximal and distal end vertebra angles (A and C), however, were unchanged or had increased at the time of the follow-up study 2 years after weaning from the brace treatment when compared with the status before the treatment. This could not be observed by using the Cobb method only. If end vertebra angles A and B are not equal, the thoracic curve is asymmetric. This asymmetry can be of two types depending on which of the two end vertebra angles is the greater one. If A is greater than B, the result of brace treatment was more successful than that of the symmetric curves.(ABSTRACT TRUNCATED AT 250 WORDS)

The natural history of idiopathic scoliosis. Incidence of treatment in 15 cohorts of children born between 1963 and 1977.

STUDY DESIGN: This study analyzed the incidence of treatment of scoliosis using a cross-sectional and a longitudinal technique. OBJECTIVES: To follow the incidence of treated scoliosis in Malmö, Sweden, in children born between 1970 and 1977 and compare observations with those of a study from 1988, in which the incidence of this disorder was followed in children born between 1963 to 1969. SUMMARY OF BACKGROUND DATA: During the late 1970s and early 1980s, the incidence of treated scoliosis decreased yearly in Malmö. This trend was supported by other reports. However, introduction of worldwide screening for scoliosis was a confounding factor. When cohorts of children born between 1963 and 1969 were analyzed, no change was found. In a study in Malmö in 1988, this was shown to be an effect of using a longitudinal instead of a cross-sectional technique of analyzing the data. METHODS: In a cross-sectional study, the authors registered all new treatments for idiopathic scoliosis, brace treatments, or direct surgery, for each year between 1984 and 1993. In a longitudinal study, all new treatments in each cohort of children born between 1970 and 1977 were followed. The results were compared with figures from the 1988 study. RESULTS: After the introduction of school screening in 1976, a peak in the incidence of treated scoliosis was seen in 1977. After a continuous decrease in the incidence until 1983, a steady state developed. In cohorts born between 1963 and 1977, the incidence is neither increasing nor decreasing. CONCLUSIONS: In cohorts of children followed in a longitudinal study over a 15-year period (born between 1963 and 1977), there is no support for a change in the natural history of idiopathic scoliosis.

The effect of lumbar flexion and Boston Thoracic Brace on the curves in idiopathic scoliosis.

The correction of scoliosis induced by pure lumbar flexion was compared with the correction with the so-called Boston Thoracic Brace. Ten patients with idiopathic scoliosis were studied. There were 11 primary curves (31 +/- 6 degrees) (mainly thoracic) and four secondary curves (22 +/- 1 degree). Pure lumbar flexion reduced the primary curves by 6 +/- 2 degrees and the secondary curves by 8 +/- 3 degrees. The brace reduced the curves by 16 +/- 6 degrees and 14 +/- 5 degrees, respectively. Lumbar flexion per se produces a correction of the scoliosis of the same degree as the Milwaukee brace. Our results emphasize the importance of reduction of the lumbar lordosis in the conservative treatment of scoliosis.

Growth in girls with adolescent idiopathic scoliosis.

The height development during childhood and puberty was analyzed in 54 girls with adolescent idiopathic scoliosis by the use of the Infancy Childhood Puberty growth model, which is based on healthy Swedish children. This model adjusts adolescent reference values for height for individual age at pubertal maturation. The scoliotic girls had an above-average height 2 years before the onset of the pubertal growth spurt. However, because they displayed an early pubertal maturation as well as a low pubertal gain in height, their values were only slightly higher than the reference mean values at maturity. The results indicate an increased growth hormone activity in childhood in girls with adolescent idiopathic scoliosis.

Postoperative instability after decompression for lumbar spinal stenosis.

Slipping after decompression for myelographically verified spinal stenosis (AP diameter less than or equal to 11 mm) was studied in 45 patients (32 men and 13 women). Mean age at the time of operation was 64 years. Mean time of postoperative observation was 46 months. The results in 29 patients were excellent or good and in 16 unchanged or worse. Degenerative spondylolisthesis was found in 20 patients and acquired spinal stenosis in 25. Postoperative slipping was seen in 18 patients. Seven belonged to the good group. A significant increase of patients with slipping was seen in the poor group (P less than 0.01). An enhanced risk of further slipping was seen in degenerative spondylolisthesis (P less than 0.01), but it did not influence the result of the operation. The radicality of the operation was about equal in both the good and poor groups and in the groups with or without postoperative slipping. A general decrease of the disc heights after operation was seen in all groups but was not significant in the poor group.

Bone mineral content, gender, body posture, and build in relation to back pain in middle age.

In 575 55-year-old residents of Malmö, Sweden, the authors studied the interrelationships between back pain and bone mineral content, degree of kyphosis and lordosis, height, and weight, and in women also the age of menarche and menopause, and number of childbirths. Men with back pain tended to be heavier than those without back pain. Back pain was not related to body height nor to degree of kyphosis or lordosis. In women, a positive correlation was found between the degree of kyphosis and lordosis and body weight. Body height in women also was correlated to degree of kyphosis, but not to the degree of lordosis. In men, the authors found no such relationships. Bone mineral content was not related to the occurrence of back pain but to body height and weight in men and in women. Back pain in women was not related to the age at menarche or menopause, nor to the number of children to whom they had given birth.

Preoperative and postoperative instability in lumbar spinal stenosis.

Sixty-one patients operated on for spinal stenosis, without a fusion, were studied retrospectively. Preoperative instability, as revealed by functional myelography, was found to predict a poor prognosis (P less than 0.01). Women had less favorable results (P less than 0.05). The "slipping" group was significantly more often radically decompressed than the "nonslipping" group (P less than 0.01). Postoperative slipping was found in 26 patients, significantly more often in those with unsatisfactory results (P less than 0.001).

Screening for scoliosis. A cost-effectiveness analysis.

The cost-effectiveness of three different screening methods was studied: the no specific screening, the conventional clinical screening, and the combined clinical moiré screening alternative. A multistage model of the treatment process was developed. Data from retrospective studies in Malmo were used. The costs for health care and production loss were calculated and applied to the time profiles of the three screening alternatives. Health care costs as well as costs in loss of production increased with the introduction of the conventional clinical screening program. However, when the clinical screening was combined with the moiré technique, the costs were markedly reduced. Thus, the combined clinical moiré screening would be the cost-effective way of using resources to prevent scolioses from developing into a more severe deformity.

Use of lumbar extension, slump test, physical and neurological examination in the evaluation of patients with suspected herniated nucleus pulposus. A prospective clinical study.

This prospective and consecutive study was designed to evaluate the validity of different clinical tests, e.g. lumbar extension in lying and slump test for patients with suspected herniated nucleus pulposus, in comparison with findings on computed tomography (CT) and/or magnetic resonance imaging (MRI) scan. There were 105 patients who were seen and examined by the senior author (for the sake of the study) at the Orthopaedic Physiotherapy Department, on an average of 5.5 days (range 0-21 days) before CT and/or MRI examination were carried out. There were 36 women and 69 men with an average age of 42.7 +/- 9.8 (range 19-64) years. According to the radiological findings on CT and/or MRI, the patients were divided into three groups: 52 patients with disc hernia, 41 patients with bulging discs and 12 patients without positive findings. The mean values with standard deviations of 25 variables of three diagnostic groups were studied. Multiple comparison adjustment according to Bonferroni showed significant differences for three variables that were of diagnostic value (lumbar range of motion for forward flexion, left side-bending in standing, and pain distribution during extension in standing). The agreement between clinical and radiological findings for type and level of diagnosis of disc herniation was accurate in 72 patients (69%). The diagnostic sensitivity for disc herniation was 82.6% and the specificity 54.7%.

Test instrument for predicting the effect of rigid braces in cases with low back pain.

The difficulty of predicting the acceptance and the result of wearing rigid braces has been identified before and is reported in the literature. Therefore a test instrument has been developed and tested. The intention is that the test instrument can imitate a rigid brace. Furthermore, different attributes of the rigid brace can be altered. Thus the range of the lordosis, the level of maximal dorsal support and the amount of abdominal support can be altered. By changing these parameters the maximal pain relief is sought. A good correlation between the result in the test instrument and the rigid brace manufactured according to the information from the former was seen (93%). No false negative results were seen. Thus, if no acceptance or pain relief was seen in the test instrument no pain relief could be expected in a rigid brace. Another purpose of this test instrument is to simplify the manufacture of the brace and to transfer easily the information gained from the test instrument to the brace with the aid of a so called measuring device.