On the distance to the North Polar Spur and the local CO-H2 factor

AIMS

Most models identify the X-ray bright North Polar Spur (NPS) with a hot interstellar (IS) bubble in the Sco-Cen star-forming region at ≃130 pc. An opposite view considers the NPS as a distant structure associated with Galactic nuclear outflows. Constraints on the NPS distance can be obtained by comparing the foreground IS gas column inferred from X-ray absorption to the distribution of gas and dust along the line of sight. Absorbing columns towards shadowing molecular clouds simultaneously constrain the CO-H₂ conversion factor.

METHODS

We derived the columns of X-ray absorbing matter N _Habs from spectral fitting of dedicated XMM-Newton observations towards the NPS southern terminus (l ^II ≃ 29°, b ^II ≃ +5 to +11°). The distribution of the IS matter was obtained from absorption lines in stellar spectra, 3D dust maps and emission data, including high spatial resolution CO measurements recorded for this purpose.

RESULTS

N _Habs varies from ≃ 4.3 to ≃ 1.3 × 10²¹ cm^-2 along the 19 fields. Relationships between X-ray brightness, absorbing column and hardness ratio demonstrate a brightness decrease with latitude governed by increasing absorption. The comparison with absorption data, local and large-scale dust maps rules out a NPS near side closer than 300 pc. The correlation between N _Habs and the reddening increases with the sightline length from 300 pc to 4 kpc and is the tightest with Planck τ _353GHz -based reddening, suggesting a much larger distance. N(H)/E(B-V) _τ ≃ 4.1 × 10²¹ cm^-2 mag^-1, close to Fermi-Planck determinations. N _Habs absolute values are compatible with HI-CO clouds at -5 ≤ V _LSR ≤ +25 to +45 km s^-1 and a NPS potentially far beyond the Local Arm. A shadow cast by a b=+9° molecular cloud constrains X _CO in that direction to ≤ 1.0 × 10²⁰ cm^-2 K^-1 km^-1 s. The average X _CO over the fields is ≤ 0.75 × 10²⁰ cm^-2 K^-1 km^-1 s.

The use of an anabolic steroid (nandrolone decanoate) to improve nutritional status after esophageal resection for carcinoma

Anabolic steroids increase appetite and muscle mass. This randomized, double-blind trial investigates any nutritional benefits of anabolic steroid in patients after surgery for esophageal cancer. Forty patients were recruited: 19 patients had five injections of 50 mg nandrolone decanoate and 21 patients received placebo over 3 months, starting 1 month after surgery. Measurements of body weight, mid-arm muscle circumference (MAMC) and appetite were taken over a 6-month period. Nutrition was optimized by dietary advice and by esophageal dilatation if required. Percent ideal weight, percent ideal MAMC and appetite score did not show significant differences between steroid and placebo groups, but there was a trend to an increase over 6 months for percent ideal MAMC in the test group. With this protocol, we have experienced minimal side-effects. However, we have not demonstrated any therapeutic benefit with low-dose steroid. An increased dose schedule over a longer period might produce a significant response.

Weight gain as an indicator of response to chemotherapy for oesophageal carcinoma

Patients with oesophageal carcinoma commonly present with dysphagia and weight loss, which may be related to the tumour burden and/or the physical obstruction to the passage of food. In this study we have examined the relationship between weight change and response to chemotherapy in 28 patients undergoing neo-adjuvant chemotherapy for squamous or anaplastic carcinoma. Two pulses of mitomycin, ifosfamide and cisplatin were given 3 weeks apart. Body weights were measured prior to the first pulse and 3 weeks after the second. Patients underwent oesophageal dilatation routinely at diagnostic endoscopy prior to chemotherapy, in order to permit oral nutrition. No dietary modifications were made. Tumour response was assessed on a barium swallow. Patients had a normal spread of weights on presentation. In the non-responding group (n = 9), eight patients lost weight and one gained weight. Of the partial responders (> 50% tumour shrinkage; n = 11), five gained weight, five lost weight and one remained constant. In the complete response group (n = 8), six gained weight and two lost weight. Statistical analysis showed a significant difference (F = 4.61; P = 0.02) between change in weight expressed as a percentage of ideal weight in nonresponders (mean -5.3%) versus partial responders (mean +2.4%), and in non-responders versus complete responders (mean +1.1%). Weight gain during chemotherapy is a good indication of response, although its absence does not preclude a response. In the majority of patients who respond to chemotherapy there will be an increase in weight with improvement in their general condition prior to operation.

Voyager 2 at Neptune: Imaging Science Results

Voyager 2 images of Neptune reveal a windy planet characterized by bright clouds of methane ice suspended in an exceptionally clear atmosphere above a lower deck of hydrogen sulfide or ammonia ices. Neptune's atmosphere is dominated by a large anticyclonic storm system that has been named the Great Dark Spot (GDS). About the same size as Earth in extent, the GDS bears both many similarities and some differences to the Great Red Spot of Jupiter. Neptune's zonal wind profile is remarkably similar to that of Uranus. Neptune has three major rings at radii of 42,000, 53,000, and 63,000 kilometers. The outer ring contains three higher density arc-like segments that were apparently responsible for most of the ground-based occultation events observed during the current decade. Like the rings of Uranus, the Neptune rings are composed of very dark material; unlike that of Uranus, the Neptune system is very dusty. Six new regular satellites were found, with dark surfaces and radii ranging from 200 to 25 kilometers. All lie inside the orbit of Triton and the inner four are located within the ring system. Triton is seen to be a differentiated body, with a radius of 1350 kilometers and a density of 2.1 grams per cubic centimeter; it exhibits clear evidence of early episodes of surface melting. A now rigid crust of what is probably water ice is overlain with a brilliant coating of nitrogen frost, slightly darkened and reddened with organic polymer material. Streaks of organic polymer suggest seasonal winds strong enough to move particles of micrometer size or larger, once they become airborne. At least two active plumes were seen, carrying dark material 8 kilometers above the surface before being transported downstream by high level winds. The plumes may be driven by solar heating and the subsequent violent vaporization of subsurface nitrogen.