bluuebunny/crossref_metadata_2025 huggingface dataset:
The foot as a donor site in reconstructive microsurgery
Authors: Morrison W. A. , O'Brien B. Mc C. , MacLeod A. M.
Published: April 2005

A common vasculature of large dimensions supplies many segments of the foot that are suitable for distant transfer for reconstructive purposes. Toes, innervated web spaces, and the dorsal skin of the foot each have unique qualities and indications as segments for transfer at the expense of minimal morbidity to the foot. Forty‐four microvascular transfers of toes, flaps, muscles, bones, and tendons have been carried out for reconstructive purposes in the hand, face, and neck over a 5‐year period. Only 2 losses have occurred, both in the first year. A significant upgrading of function and reduction of disfigurement has followed the majority of these procedures. Sometimes the tissues have been used in combination, as in neurovascular free flaps and combined dorsum of the foot flap and second metatarsal. This series of cases demonstrates the unique capacity of the foot as a donor site in reconstructive surgery.
Microsurgery of peripheral nerves
Authors: Millesi H.
Published: April 2005

Development of microsurgical techniques represents a major advance in the surgery of peripheral nerves. The operating microscope makes it possible to evaluate the severity of trauma to nerve tissue more accurately than other methods. Microsurgery has made it possible to perform atraumatic interfascicular dissection in operations for various nerve lesions, including tumors, fibrosis due to irritation, compression or ischemia, and traumatic injuries with preserved continuity. Interfascicular dissection has proved to be particularly useful in nerve segments with a polyfascicular pattern and group arrangement. The results of nerve grafting have been improved significantly by microsurgical techniques.
Prevention of hepatic failure following jejunoileal bypass by a modification of Payne's operation
Authors: Messaris G. E. , Mariatos C. G. , Mazis A. , Statherou P.
Published: April 2005

Hepatic failure is the leading cause of death after bypass procedures for morbid obesity. The bypassed blind segment is considered to be the etiologic factor. An experimental study in 12 dogs was carried out to determine the effects of modifying the blind segment. Three dogs had 85% of the small intestine resected, 3 dogs had 85% of the small intestine bypassed (Payne's operation), and 6 dogs had 85% of the small intestine bypassed but the proximal end of the jejunum, which in Payne's operation is closed and produces a long blind segment, was anastomosed end‐to‐side to the terminal ileum, 10 cm proximal to the main anastomosis. The resultant “semi‐open” segment is partially activated and “washed” by recirculation of a small portion of refluxing intestinal contents (estimated as 5% of the total). Hepatic function was determined by laboratory tests and liver biopsies.

All dogs in the first group developed weight loss without any liver abnormality. All dogs in the second group developed progressive weight loss and liver necrosis and died in a mean 77 days. All dogs in the third group developed weight loss similar to that of the first group, but only mild aberration of liver function, which returned to normal within 6 months.
Acute pancreatitis. A study of 122 patients with acute pancreatitis observed for 5–15 years
Authors: Madsen Ole Guldberg , Schmidt Arne
Published: April 2005

A study was performed of 122 patients admitted for acute pancreatitis during the decade 1960–1970. Gallstones were found in 14% and abuse of alcohol in 40%. Ten patients (8%) died before leaving the hospital, and a further 36 died during the follow‐up period from 1960–1975. Compared with the general population of similar age and sex, the mortality rate was significantly increased (p<0.01). The recurrence rate during the follow‐up period was 43%, and 2/3 of those patients had more than one recurrence. The 76 patients who survived were called for follow‐up, but 12 could not be traced. Of the 64 patients who were traced, 83% had no complaints or only moderate complaints, while 14% had severe complaints, and 3% were incapacitated by pain and other symptoms; 17% had continued to drink alcohol. It is concluded that patients admitted to hospital with acute pancreatitis have a significantly higher mortality compared with the normal population. We did not obtain conclusive data that a continued high alcohol consumption worsens the prognosis.
In vitro regeneration of adenine nucleotide by ischemically injured kidney
Authors: Collins Geoffrey M. , Green Richard D. , Halasz Nicholas A.
Published: April 2005

Degradation of adenine nucleotide is a prominent feature of renal ischemic injury, the significance of which is still uncertain. In the present study, the conditions required for regeneration of adenine nucleotide by ischemically injured rabbit and dog kidneys were investigated using a slice incubation and isolated organ perfusion model. Regeneration in the whole organ was dependent on species, temperature, colloid concentration, and the presence of nucleoside as substrate. Under optimal conditions, slice incubation and perfusion yielded comparable results, and regeneration by ischemic tissue was equivalent to that of fresh tissue. These data suggest that the low adenine nucleotide levels after ischemic injury do not result from metabolic failure so much as from a local unavailability of substrate.
Malignant melanoma metastatic to the gastrointestinal tract
Authors: Giler Shamai , Kott Itamar , Urca Israel
Published: April 2005

Five patients with symptomatic metastases of malignant melanoma to the gastrointestinal tract are presented. The clinical and pathological findings are reviewed. It seems that metastases of malignant melanoma to the gastrointestinal tract are more frequent than has previously been assumed. The clinical symptoms are usually variable and include vague abdominal pain or discomfort, gastrointestinal bleeding, and intestinal obstruction. Although the prognosis is poor, surgical excision is indicated in selected patients.
Jejunal replacement after pharyngo‐laryngo‐esophagectomy for carcinoma of hypopharynx
Authors: Ong G. B. , Wong John
Published: April 2005

A patient with recurrent carcinoma of the larynx following irradiation therapy was subjected to pharyngo‐laryngoesophagectomy. Since he had had a previous Polya gastrectomy and the large bowel was not prepared, jejunum was used for esophageal replacement. This is the first patient in whom jejunum was used for anastomosis to the pharynx in our series of over 100 such operations. A satisfactory result was obtained.
Simple mastectomy and pectoral node biopsy: The Cardiff‐St. Mary's trial
Authors: Forrest A. P. M. , Roberts M. M. , Cant E. L. M. , Henk M. , Hughes L. E. , Hulbert M. , Dudley H. A. , Campbell H.
Published: April 2005

Between 1967 and 1973, 243 patients with breast cancer classified clinically as stages I and II were assigned by random sample to 2 major treatment groups and a number of subgroups. The 2 groups were treated by either simple mastectomy (with pectoral lymph node biopsy) or radical mastectomy. All patients with positive lymph nodes on histological examination received supplementary postoperative treatment which, in the simple mastectomy group, consisted of local radiotherapy to the axilla and, in the radical mastectomy group, consisted of radical radiotherapy to the axilla, chest wall, supraclavicular region and internal mammary region. By March 30, 1976, 166 of the 243 patients had completed 5 years of follow‐up observation. There was no significant difference in survival rate, duration of life, incidence of disseminated cancer, or time of appearance of metastases between the conservative and radical treatment groups. The only significant difference observed in the trial occurred in patients with positive lymph nodes in whom treatment by radical mastectomy plus radical radiotherapy was associated with a significantly lower incidence of local cancer recurrence than was conservative treatment. Assessment of morbidity in 85 patients showed that patients with negative lymph nodes had significantly less morbidity following simple mastectomy than after radical mastectomy.
Emergency esophageal transection with paraesophagogastric devascularization for variceal bleeding
Authors: Futagawa Shunji , Sugiura Mitsuo , Hidai Koh , Shima Fumio
Published: April 2005

Since 1967, a total of 52 patients with portal hypertension have undergone emergency esophageal transection with paraesophagogastric devascularization in 2 stages, 4–6 weeks apart, to control variceal bleeding. According to the Child classification, 8 patients were class A, 19 were class B, and 25 were class C. The etiology of the portal hypertension was cirrhosis of the liver in 30 patients, liver fibrosis in 13, extrahepatic portal vein occlusion in 4, hepatoma in 4, and carcinoma of the pancreas in 1 patient. There were 6 operative deaths (11.5%), caused by progressive hepatic failure (2), hepatoma (2), renal failure (1), and intraperitoneal bleeding (1). The operative mortality rate in the class A and B patients was 0%, but in the class C patients, it was 24%. The operative mortality rate for cirrhotic patients was 10%. There have been 9 late deaths due to hepatic failure (2), hepatoma (4), esophageal variceal bleeding (2), and carcinoma of the pancreas (1). At present, 88% of class B patients are alive, but only 56% of class C patients are alive. There was an obvious positive correlation between survival rate and the stage of the disease. Only 2 patients with incomplete devascularization developed recurrent esophageal variceal bleeding and died (recurrence rate of 4.3%). All survivors are free of hepatic encephalopathy.

This method provided excellent results in controlling variceal bleeding without causing hepatic dysfunction and encephalopathy and is indicated in all patients with variceal bleeding except those with severe hepatic failure.
Prevention and management of hypothyroidism after thyroidectomy for thyrotoxicosis
Authors: Michie W. , Beck J. Swanson , Pollet J. E.
Published: April 2005

Postoperative hypothyroidism is the most common complication of thyroidectomy for thyrotoxicosis. Its incidence is inversely related to remnant size. Destructive autoimmunity, as measured by the presence of antithyroid antibodies in the serum, may be another of the factors predisposing to postoperative hypothyroidism, but the extent to which such considerations should influence remnant size is a matter for debate. Experience in Iceland suggests that high iodine ingestion is associated with a low incidence of hypothyroidism and a high rate of recurrent thyrotoxicosis; consequently, smaller remnants are obligatory in Iceland. Therefore, it would seem that environmental factors also play a part, and that a remnant “norm” for each locality should be determined empirically to achieve optimum balance between hypothyroidism and recurrent thyrotoxicosis. With the establishment of a “norm,” prediction of hypothyroidism for a group of patients is reasonably accurate. For the individual patient, postoperative status cannot be predicted and it is not possible to select for alternative methods of treatment patients who might be at risk of postoperative hypothyroidism.

Irrespective of large remnant size, approximately 15% of patients will develop postoperative hypothyroidism. These may be the patients described at the turn of the century, before effective treatment became available, in whom the natural course of the disease progressed through euthyroidism to hypothyroidism. It would appear, for some patients at least, that surgery merely accelerates the natural course of the disease and compresses into a matter of weeks events which normally take several months and even years. Fortunately, postoperative hypothyroidism declares itself within 12–15 months and, if clinical scrutiny is sufficiently acute, late onset hypothyroidism is rare. The ethical responsibility remains for a prolonged follow‐up of all postthyroidectomy patients.
Needle aspiration and needle biopsy of the thyroid
Authors: Esselstyn Caldwell B. , Crile George
Published: April 2005

A definitive preoperative diagnosis is not readily available for the majority of patients with an enlarging thyroid gland or nodule, but thyroid needle biopsy yields an immediate, safe, and accurate histopathologic diagnosis. In a review of 460 patients having thyroid needle biopsy at the Cleveland Clinic from 1967 to 1976, sufficient biopsy material was available for diagnosis in 410 patients. In 44 patients operations were performed for benign disease for a variety of reasons. In 23 patients operations were performed for thyroid malignancy; in 14 of the latter group the diagnosis was made by needle biopsy and confirmed surgically. Of 9 other patients operated on for thyroid malignancy, 6 had thyroid surgery because needle biopsy showed a follicular neoplasm in which malignancy could not be ruled out, and in the remaining 3, clinical findings and the hypercellular nature of the biopsy prompted operation. In an additional 9 patients thyroid malignancy was diagnosed by needle biopsy, but no operation was performed (1 because of age and prohibitive cardiac risk, 2 because the cancer was metastatic to the thyroid from a separate primary, and 6 because the neoplasms were lymphoma or small cell undifferentiated carcinomas that were treated by radiotherapy). There were 3 complications in 460 biopsies (transient recurrent nerve palsy, hematoma, and local discomfort), all of which were short‐lived and minimal. The true value of needle biopsy was that 393 patients with benign disease were spared unnecessary surgery. After a quarter century of experience with this technique, the authors propose that needle biopsy be used more often to eliminate the mortality, morbidity, and significant cost of unnecessary thyroid surgery, and the uncertainty and expense of less accurate diagnostic methods.
Survival after mastectomy for breast cancer: Predictive value of lymphocyte count and its change after mastectomy in patients with metastases to one to three axillary nodes
Authors: Meyer Kenneth K.
Published: April 2005

A low preoperative lymphocyte count that increased after mastectomy was found to be a probably effective predictor of disease‐free survival in women with breast cancer and histologically proven metastases to 1–3 axillary nodes only. Two of 44 patients with < 2,000 lymphocytes/mm3, and 16 of 30 with > 2,000 lymphocytes/mm3 preoperatively developed recurrence within 5 years after mastectomy (p<0.001). Eight patients died and all had preoperative lymphocyte counts of > 2,000/mm3 (p<0.0001). None of 17 patients whose lymphocyte count remained unchanged or rose 1 week postoperatively developed recurrence, while 6 of 14 whose count fell did so (p<0.01). Postmastectomy irradiation was followed by a significant increase in metastases when the preoperative count was <2,000 lymphocytes/mm3 (9 of 28 patients), compared to when the count was > 2,000/mm3 (2 of 44 patients) (p<0.01).

Patients with histologically proven metastases to 1–3 axillary nodes whose preoperative total lymphocyte count is < 2,000/mm3 require no adjuvant therapy and seem to be made worse by radiation therapy. Those with > 2,000 lymphocytes/mm3 will probably benefit from adjuvant chemotherapy.
Importance of surgical technique in prevention of retained and recurrent bile duct stones
Authors: Orloff Marshall J.
Published: April 2005

Approximately 10% of the 500,000 patients who undergo cholecystectomy for gallstones each year in the U.S.A. have associated choledocholithiasis. Of the patients who have a choledocholithotomy, 10–13% are found to have retained bile duct stones in the immediate postoperative period, and an unknown additional number are found to have biliary calculi subsequently. Residual bile duct calculi come from 3 sources, namely, “retained” stones that were overlooked during the initial operation, “retained” stones that were recognized but could not be removed at the initial operation, and “recurrent” stones that re‐form in the bile ducts in association with highly lithogenic bile. Most retained stones can be prevented by knowing when and how to perform common bile duct exploration. Absolute indications, which have a high yield of calculi, are: (a) palpable stones, (b) obstructive jaundice with cholangitis, (c) demonstration of stones by cholangiography, and (d) dilatation of the common duct beyond a diameter of 12 mm. Relative indications, use of which requires judgment because of a generally low yield of calculi, are: (a) jaundice without cholangitis, (b) biliary‐enteric fistula, (c) small stones in the gallbladder, (d) a single‐faceted gallbladder stone, and (e) pancreatitis.

Technical aspects of common duct exploration that are important for prevention of retained bile duct calculi include: (a) routine use of a Kocher maneuver, (b) routine preexploratory operative cholangiography, (c) use of the balloon‐tipped catheter, (d) routine completion cholangiography through a T tube, and (e) operative biliary endoscopy. A large number of retained stones results from inadequate operative cholangiography due to poor radiographic equipment, inattention to details of technique, and insufficient collaboration between radiologist and surgeon.

Since approximately 25% of reoperations for residual stones are followed by subsequent recurrence of choledocholithiasis, sphincteroplasty and choledochoduodenostomy play an important role in prevention of recurrent calculi. Use of these adjunctive biliary drainage procedures is indicated: (a) when it is impossible to surgically extract bile duct stones or for impacted ampullary stones, (b) when the biliary tree is “packed” with many stones, (c) when reoperation is required for primary bile duct stones, (d) in third operations for bile duct calculi of any type, and (e) rarely, when bile duct stones are associated with stenosis of the papilla of Vater.
Choledochoscopy and operative fluorocholangiography in the prevention of retained bile duct stones
Authors: Berci George , Shore J. Manny , Morgenstern Leon , Hamlin J. Andrew
Published: April 2005

Choledochoscopy has become a clinically accepted adjunct to choledochotomy as a result of recent advances in optics and instrumentation technology. Experience with this diagnostic modality during the past 18 years has led to the development of a compact, right‐angled, rigid, rod‐lens choledochoscope. Because of the excellent image quality and easy manipulation of this new instrument, choledochoscopy can be easily incorporated into routine surgical procedures on the biliary tract. Clinical results of choledochoscopy in a recent series of 120 consecutive choledochotomies are presented. The incidence of retained stones was reduced to 2%. Further advantages were: direct endoscopic removal of calculi, biopsy of biliary tumors, and immediate interpretation of questionable operative cholangiograms. Direct visual diagnosis of the problematic distal duct facilitated appropriate operative management without prolonging operating time. The procedure was carried out without increasing the complication rate beyond that of standard choledochotomy.

The standard technique of operative cholangiography, using a portable x‐ray machine, has many disadvantages, including extended operating time, blind exposure of the films, a high incidence of blurred or technically inadequate films, and frequent need to repeat the procedure. A technique of operative fluorocholangiography is described which uses fixed equipment that incorporates modern advances in diagnostic radiology, but is modified to suit the surgical environment. The contrast material inflow is observed by television‐fluoroscopy and the exposures, using indirect radiographic techniques, are made under visual control. The advantages of this new technique are: aimed small format film technique, automatic exposure (brightness, contrast) control, serial films (6–12 instead of 3), reduction of radiation, high quality films, and a significant decrease of time required for a complete examination (5 min). The value of operative fluorocholangiography is emphasized for assessment of sphincter function and duct motility, as well as for the localization of bile duct stones.
Transduodenal endoscopic sphincterotomy and extraction of bile duct stones
Authors: Safrany Laszlo
Published: April 2005

Retained and recurrent common bile duct stones have required surgical treatment. Recent advances in endoscopy, however, have made possible endoscopic management of choledocholithiasis. This report describes the method of endoscopic sphincterotomy and the results in 562 patients with choledocholithiasis in whom the procedure was attempted during the past 4 years. Endoscopic sphincterotomy was successfully accomplished in 523 patients (93%). There were 428 patients with retained or recurrent common bile duct stones after cholecystectomy. In 95 high‐risk patients with choledocholithiasis and cholelithiasis, endoscopic sphincterotomy was carried out to relieve jaundice. In 188 patients the stones passed spontaneously after sphincterotomy. In 306 patients, the stones were extracted. Residual stones remained in 29 patients. Complications consisting of bleeding, retroperitoneal perforation, pancreatitis, cholangitis, and stone impaction occurred in 36 patients (6.9%). In 10 patients (1.9%), complications made emergency surgery necessary and resulted in 5 deaths for a mortality rate of 1%. The good results, low morbidity, and low mortality of endoscopic sphincterotomy support the suggestion that this method of treatment has earned a firm place in modern biliary surgery.
The prevention and treatment of recurrent bile duct stones by transduodenal sphincteroplasty
Authors: Jones S. Austin
Published: April 2005

Sphincteroplasty is a transduodenal method of producing a terminal choledochoduodenostomy as wide as the supraduodenal common duct. The sphincters affecting common and pancreatic ducts are destroyed, making the opening noncontractile and permanent. To achieve this, the common and duodenal walls are divided between clamps and oversewn. The resulting stoma differs anatomically and physiologically from that of sphincterotomy, which leaves functioning sphincter behind. This is demonstrable by postoperative T‐tube pressure and flow studies before and after morphine, and free reflux and stomal permanence after sphincteroplasty. Such an opening prevents trapping of overlooked stones or bile stasis with stone formation.

Sphincteroplasty has been performed in a series of 312 patients with a mortality of 0.96% and a morbidity of 4.7%. There have been no deaths in the last 200 patients. There were 211 operations performed for obstructive biliary disease, on the basis of 1 or more indications: multiple common duct stones were present in 187, irremovable hepatic duct calculi in 4, and residual stone in 22 referred patients. In addition, miscellaneous indications for operation included papillary stenosis, strictures, irremovable calculi, and mud and sludge. All 211 patients were relieved of bile duct obstruction and there were no residual stones following sphincteroplasty.

It is stressed that sphincteroplasty is one of several ways to achieve free bile duct drainage. These methods should not be considered competitive. The operation selected should be tailored to meet the specific situation at hand.
Clinical and experimental studies of oral 5‐FU emulsion as an adjuvant to the surgical treatment of gastric cancer
Authors: Nishioka Bunzo , Watanabe Shinsuke , Fujita Yoshihiro , Majima Susumu , Takahashi Toshio
Published: April 2005

Based on the propensity of fat emulsion to be absorbed mainly into lymphatic capillaries and regional lymph nodes, we studied experimentally and clinically the effectiveness of oral administration of a 5‐fluorouracil (5‐FU) emulsion as an adjuvant to surgery in the treatment of gastric cancer, especially when there were lymph node metastases. Experiments in rats showed that drug concentration in the regional lymph nodes was higher and remained longer after oral administration of 5‐FU emulsion than after oral administration of an aqueous solution of 5‐FU. Furthermore, measurement of the concentration of 5‐FU in the regional lymph nodes of 13 patients with gastric cancer who had been given the 5‐FU emulsion or 5‐FU in water orally 2 hours before surgery showed that the mean 5‐FU level was higher in the patients that received the emulsion than in those who received the aqueous solution. In the past 3 years, we have administered 5‐FU emulsion to 123 patients with gastric cancer for a period of 1–3 weeks before surgery, and examined histologically the effect of this therapy on the met astatic foci in the lymph nodes. A positive change, such as marked necrosis or marked degeneration, was found in 62% of the metastatic lesions. The results suggest that preoperative oral administration of 5‐FU emulsion may be effective as an adjuvant to surgery for gastric cancer, particularly in patients with metastases to lymph nodes.
Late results of perforated duodenal ulcer treated by simple suture
Authors: Skovgaard Søren
Published: April 2005

A study was performed of 156 patients who underwent follow‐up evaluations 3 to 23 years (mean 13 years) after simple closure of a perforated duodenal ulcer. Subsequent definitive ulcer surgery was indicated in 111 patients (71%) for severe recurrent dyspepsia. Bleeding, reperforation or pyloric obstruction occurred in 14 patients (9%). Among 33 patients (21%) with an ulcer history of less than 3 months prior to perforation, only 4 (12%) required further surgery while a subsequent operation was indicated in 107 of 123 patients with a longer ulcer history. Immediate definitive surgery is indicated for perforated duodenal ulcer in patients with ulcer symptoms for more than 3 months before perforation. Simple suture of the perforation is sufficient treatment for patients with a shorter ulcer history.
Hypercalcemia and urinary excretion of cyclic AMP in bronchogenic carcinoma
Authors: Francini Guido , Galli Marco
Published: April 2005

Plasma calcium and phosphate levels and the cyclic AMP/creatinine ratio in the urine were studied in 23 patients with bronchogenic carcinoma. Hypercalcemia was found in 4 patients (17.4%), confirming the frequency of this abnormality observed by others. However, only one patient had both hypercalcemia and hypophosphatemia. In 4 patients with hypercalcemia and no bone metastases, surgical removal of the tumor was followed by return of the plasma calcium level to normal, suggesting that the hypercalcemia was caused by ectopic secretion of a parathormone‐like substance by the neoplasm. Contrary to what might be expected, the urinary cAMP/Cr ratio was abnormally low in most patients, including 3 of the 4 patients with hypercalcemia. Moreover, the cAMP/Cr ratio in the urine did not decrease after removal of the tumor. This finding suggests another difference between PTH‐like substances of neoplastic origin and natural PTH if, indeed, a PTH‐like substance was responsible for the hypercalcemia.
Use of an external bypass technique in gastrointestinal and biliary surgery
Authors: Zer M. , Mukamel E. , Dintsman M.
Published: April 2005

A simple, easily employed method of external bypass in gastrointestinal and biliary surgery is described. This method aims to minimize fluid loss through postoperative leaks, thereby preventing the complications which may ensue, and also is effective in achieving decompression of a viscus without causing diversion of the biliary and gastrointestinal enzymes from the gastrointestinal tract.
Intraluminal techniques for vena caval interruption and pulmonary embolectomy
Authors: Greenfield Lazar J.
Published: April 2005

Although most patients who sustain thromboembolism can be managed by anticoagulation, a number of them benefit from mechanical protection against further embolism or require embolectomy for survival. Intraluminal approaches have been developed recently as an alternative to major surgical procedures for these aims and show improved effectiveness and reduced morbidity and mortality rates. Clinical results using the Kimray‐Greenfield vena caval filter in 76 patients since 1972 include a mortality rate of 4% within 2 weeks after operation and 17.1% thereafter due to underlying disease. Recurrent thromboembolism was seen in 2.6% and the incidences of thrombophlebitis and extremity edema were comparable to the experience with the Mobin‐Uddin umbrella. In contrast to that experience, migration of the filter has not occurred and the postoperative vena cava patency rate at 11 months by venacavography is 97%. Transvenous pulmonary embolectomy has been performed in 22 patients and the development of a steerable catheter with simultaneous insertion of the vena caval filter reduced the operative mortality rate from 40% to 17%. Emboli were removed in 86% of patients and overall survival has been 14 of 22 patients (64%). Catheter embolectomy under local anesthesia provides a useful alternative to open embolectomy requiring cardiopulmonary bypass.
Shear flow instabilities in the earth's plasma sheet region
Authors: Kalra Sunayna , Lakhina G. S.
Published: April 2005

Abstract. Shear flow instability arising from the velocity shear between the inner and the outer central plasma sheet regions is studied by treating the plasma as compressible. Based on the linearized MHD equations, dispersion relations for the surface wave modes occurring at the boundary of the inner central plasma sheet (ICPS) and the outer central plasma sheet (OCPS) are derived. The growth rates and the eigenmode frequencies are obtained numerically. Three data sets consisting of parameters relevant to the earth's magnetotail are considered. The plasma sheet region is found to be stable for constant plasma flows unless MA>9.6, where MA is the Alfvén Mach number in the ICPS. However, for a continuously varying flow velocity profile in the ICPS, the instability is excited for MA\\geq1.4. The excited modes have oscillation periods of 2-10 min and 1.5-6 s, and typical transverse wavelengths of 30-100 RE and 0.5-6 RE for data sets 1 and 2 (i.e., case of no neutral sheet) respectively. For the data set 3, which corresponds to a neutral sheet at the center of the plasma sheet, the excited oscillations have periods of 2 s-1 min with transverse wavelengths of 0.02-1 RE.
Possible evidence for partial demagnetization of electrons in the auroral E-region plasma during electron gas heating
Authors: Haldoupis C.
Published: April 2005

Abstract. A previous study, based on incoherent and coherent radar measurements, suggested that during auroral E-region electron heating conditions, the electron flow in the auroral electrojet undergoes a systematic counterclockwise rotation of several degrees relative to the E×B direction. The observational evidence is re-examined here in the light of theoretical predictions concerning E-region electron demagnetization caused by enhanced anomalous cross-field diffusion during strongly-driven Farley-Buneman instability. It is shown that the observations are in good agreement with this theory. This apparently endorses the concept of wave-induced diffusion and anomalous electron collision frequency, and consequently electron demagnetization, under circumstances of strong heating of the electron gas in the auroral electrojet plasma. We recognize, however, that the evidence for electron demagnetization presented in this report cannot be regarded as definitive because it is based on a limited set of data. More experimental research in this direction is thus needed.
Recent observations of MHD fluctuations in the solar wind
Authors: Bavassano B.
Published: April 2005

Abstract. A short review of recent observations of solar wind fluctuations in the magnetohydrodynamic (MHD) range of scales is presented. In recent years, the use of high time-resolution data on an extended interval of heliocentric distance has allowed significant advances in our knowledge of MHD fluctuations. We first focus on the origin and evolution of the Alfvénic-type fluctuations. The role of interplanetary sources and the influence of interactions with structures convected by the solar wind are examined. Then compressive fluctuations are investigated, with special attention being given to their nature and origin. Observations are discussed in the light of recent theories and models. Finally, predictions for MHD turbulence in polar regions of the heliosphere are highlighted.
Selected solar wind parameters at 1 AU through two solar activity cycles
Authors: Bruno R. , Villante U. , Stecca A.
Published: April 2005

Abstract. In situ measurements of the solar wind largely cover more than two solar magnetic activity cycles, namely 20 and 21. This is a very appealing opportunity to study the influence of the activity cycle on the behaviour of the solar wind parameters. As a matter of fact, many authors so far have studied this topic comparing the long-term magnetic field and plasma averages. However, when the average values are evaluated on a data sample whose duration is comparable with (or even longer than) the solar rotation period we lose information about the contribution due to the fast and the slow solar wind components. Thus, discriminating in velocity plays a key role in understanding solar cycle effects on the solar wind. Based on these considerations, we performed a separate analysis for fast and slow wind, respectively. In particular, we found that: (a) fast wind carries a slightly larger momentum flux density at 1 AU, probably due to dynamic stream-stream interaction; (b) proton number density in slow wind is more cycle dependent than in fast wind and decreases remarkably across solar maximum; (c) fast wind generally carries a magnetic field intensity stronger than that carried by the slow wind; (d) we found no evidence for a positive correlation between velocity and field intensity as predicted by some theories of solar wind acceleration; (e) our results would support an approximately constant divergence of field lines associated with corotating high-velocity streams.
A study of quasi-periodic ELF-VLF emissions at three Antarctic stations: evidence for off-equatorial generation?
Authors: Morrison K. , Engebretson M. J. , Beck J. R. , Johnson J. E. , Arnoldy R. L. , Cahill L. J. , Carpenter D. L. , Gallani M.
Published: April 2005

Abstract. The spatial extent and temporal behaviour of quasi-periodic (QP) intensity modulations of 0.5-2 kHz ELF-VLF signals were investigated in a comparative study of data collected at the Antarctic stations of South Pole (L=14), Halley (L=4), and Siple (L=4). Frequently, the waveforms of ELF-VLF signals simultaneously received at each site were identical. Although of similar frequency structure, the waveforms of the accompanying Pc3 magnetic pulsations did not show a one-to-one association. Whereas both are dayside phenomena, QP emissions occur over a smaller range of local times, and have a maximum of occurrence later in the day closer to local noon. QP emissions are identified with the periodic modulation of the electron pitch-angle distribution by the propagation of ULF compressional fast-mode waves through a region. However, contrary to previous ideas, rising-tone emissions do not represent the frequency-time signatures of such waves. In addition to generation close to the equatorial plane, we propose an additional high-latitude source of QP emissions. These emissions are associated with regions of minimum B produced by the dayside compression of the magnetosphere close to the magnetopause. Model magnetic field calculations of these minimum-B regions as a function of magnetic local time and invariant latitude are presented.
Coherent multiple Pc1 pulsation bands: possible evidence for the ionospheric Alfvén resonator
Authors: Feygin F. Z. , Nekrasov A. K. , Mursula K. , Kangas J. , Pikkarainen T.
Published: April 2005

Abstract. A fair fraction of Pc1 pulsation events observed on the ground includes more than one simultaneous pulsation band. In most such multiband events the bands display different characteristics and, therefore, come from different source regions via horizontal ducting in the ionosphere. However, in this report we identify a new "coherent" subclass of multiband Pc1 events where the pearls of the simultaneous bands have the same group velocities (repetition rates) as well as dispersion and other properties, thus implying that the bands are produced by the same source. Studying one example of such a coherent multiband event in more detail, we argue that these events defy an explanation in terms of band splitting by magnetospheric heavy ions because the observed frequency gap between the bands is smaller than would result in such a case. We interpret these events to be due to the frequency dependence of the ionospheric reflection coefficient of Alfvén waves. An oscillatory frequency dependence of the coefficient is a natural consequence of the idea that the ionosphere acts as a resonator for Alfvén waves. We also discuss other predictions of this interpretation.
Magnotospheric imaging of high latitude ion outflows
Authors: Garrido D. E. , Robinson R. M. , Chiu Y. T. , Collin H. L. , Smith R. W. , Swift D. W.
Published: April 2005

Abstract. High latitude ion outflows mostly consist of upward streaming O+ and He+ emanating from the ionosphere. At heights above 1000 km, these flows consist of cold and hot components which resonantly scatter solar extreme ultraviolet (EUV) light, however, the ion populations respond differently to Doppler shifting resulting from the large relative velocities between the ions and the Sun. The possibility of optical detection of the Doppler effect on the scattering rate will be discussed for the O+ (83.4 nm) ions. We have contrasted the EUV solar resonance images of these outflows by simulations of the 30.4 nm He+ and 83.4 nm O+ emissions for both quiet and disturbed geomagnetic conditions. Input data for the 1000 km level has been obtained from the EICS instrument aboard the Dynamics Explorer satellite. Our results show emission rates of 50 and 56 milli-Rayleighs at 30.4 nm for quiet and disturbed conditions and 65 and 75 milli-Rayleighs at 83.4 nm for quiet and disturbed conditions, respectively, obtained for a polar orbiting satellite and viewing radially outward. We also find that an imager at an equatorial distance of 9 RE or more is in a favourable position for detecting ion outflows, particularly when the plasmapause is depressed in latitude. However, an occultation disk is necessary to obscure the bright plasmaspheric emissions.
Multitechnique studies of nor'wester using electrical and meteorological parameters
Authors: Bhattacharya A. B.
Published: April 2005

Abstract. Radar observations of nor'wester (premonsoon thunderstorm) as experienced over the Gangetic West Bengal and the integrated field intensity of atmospherics (IFIA) at 10, 20 and 30 kHz recorded over the tropical station at Calcutta have been analysed. The records of IFIA reveal that, during nor'wester, the enhancement in the signal level occurs in three different stages: (i) gradual rise of atmospherics (GRA), (ii) first sudden enhancement of atmospherics (SEA1) and (iii) second sudden enhancement of atmospherics (SEA2). Their respective occurrences have been found to be prevalent in pre-noon, latenoon and afternoon hours of a day. Of the three stages, GRA and SEA1 have been found to occur before the onset of thunderstorm, while SEA2 may even occur after its onset. A comparative study reveals that the precipitation during premonsoon thunderstorms is associated with the second sudden enhancement, while it is associated with the steady recovery of IFIA during the monsoon and postmonsoon thunderstorms. The characteristics of the first nor'wester of every year have been critically examined with an additional consideration of simultaneous radiosonde records. A probable explanation has been made in terms of the distribution of the effective sources at such times around the observing site.
Temporal and spatial variations of the atmospheric dust loading throughout West Africa over the last thirty years
Authors: N'Tchayi G. M. , Bertrand J. , Legrand M. , Baudet J.
Published: April 2005

Abstract. The dust haze conditions, typical of the African atmosphere south of the Sahara, are a result of wind-generated dust from arid lands. The magnitude of the dust haze is evaluated for the 30-year period beginning in 1957 by calculating the number of occurrences where the observed visibility was reduced below threshold values of 10 km and 5 km. The frequency of low visibility was several times greater for the 1977-1986 period than for the 1957-1966 period. Large decreases in visibility are observed after the severe droughts of 1972-1973 and 1982-1984. Contrasting regional differences of the dustiness evolution are noticed. These differences are closely related to the differences in the regional rainfall evolution. The increase in dustiness is believed to arise from dust produced in new desertic areas which result from rainfall shortages along the southern border of the Sahara.
The effect of disturbed-time electric fields on the inner plasmasphere
Authors: Balmforth H. F. , Moffett R. J. , Smith A. J. , Bailey G. J.
Published: April 2005

Abstract. Results from a mathematical model provide a description of the mid-latitude, low L-shell ionosphere and plasmasphere. Variations in the composition and dynamics of the plasmasphere and changes in the nature of the coupling between the plasmasphere and the ionosphere are studied for moderately disturbed conditions. Modelled results are compared to group delay and Doppler shift measurements of whistler mode signals at Faraday, Antarctica (L ≈ 2.5), to investigate the effects of disturbed time electric fields on the inner plasmasphere and ionosphere. The disturbed time electric field causes a rapid outward drifting of the plasma leading to a decrease in modelled plasmaspheric electron density at a fixed L-value, which agrees with experimental observations. During the periods of outward drift, the modelled coupling flux is upwards to the plasmasphere which can lead to a significant depletion of NmF2 values.
Relationships between field-aligned currents and convection observed by EISCAT and implications concerning the mechanism that produces region-2 currents: Statistical study
Authors: Peymirat Christophe , Fontaine Dominique
Published: April 2005

Abstract. Fluid theories explain the origin of region-2 field-aligned currents as the closure of the ring current, driven itself by the azimuthal pressure gradients generated in the magnetospheric ring plasma by the sunward convection. Although the structure of pressure gradients appears experimentally complex, observations confirm that a close connection exists between the region-2 field-aligned currents and the ring current. The fluid linear theory of the adiabatic transport by convection of the ring plasma gives a first estimate of this process, and leads ultimately to phase quadrature (in terms of magnetic local time) between the region-2 field-aligned currents and the convection potential. When significant non-adiabatic processes are taken into account, such as precipitations at auroral latitudes, the theoretical phase difference rotates toward opposition. We determine experimentally the phase relationship between the region-2 field-aligned currents and the convection potential from recent statistics, depending on the magnetic activity index Kp, and performed from the EISCAT data base. For geometrical reasons of sufficient probing of region 2, it is only computed in the case of a moderate magnetic activity corresponding to 2 ≤ Kp<4. Region-2 field-aligned currents are found to be in phase opposition with the convection electrostatic potential at auroral latitudes. This confirms the importance of non adiabatic processes, especially ion losses, in the generation of region-2 field-aligned currents, as theoretically suggested.
The role of natural E-region plasma turbulence in the enhanced absorption of HF radio waves in the auroral ionosphere:Implications for RF heating of the auroral electrojet
Authors: Robinson T. R.
Published: April 2005

Abstract. Physical processes which affect the absorption of radio waves passing through the auroral E-region when Farley-Buneman irregularities are present are examined. In particular, the question of whether or not it is legitimate to include the anomalous wave-enhanced collision frequency, which has been used successfully to account for the heating effects of Farley-Buneman waves in the auroral E-region, in the usual expression for the radio-wave absorption coefficient is addressed. Effects also considered are those due to wave coupling between electromagnetic waves and high-frequency electrostatic waves in the presence of Farley-Buneman irregularities. The implications for radio-wave heating of the auroral electrojet of these processes are also discussed. In particular, a new theoretical model for calculating the effects of high-power radio-wave heating on the electron temperature in an electrojet containing Farley-Buneman turbulence is presented.
Simulating the global transport of nitrogen oxides emissions from aircraft
Authors: Sausen R. , Köhler I.
Published: April 2005

Abstract. With the atmosphere general circulation model ECHAM the passive transport of NOx emitted from global subsonic air traffic and the NOx concentration change due to these emissions are investigated. The source of NOx is prescribed according to an aircraft emission data base. The sink of NOx is parameterized as an exponential decay process with globally constant lifetime. Simulations in perpetual January and July modes are performed. Both the resulting mean and the standard deviation of the NOx mass mixing ratio are analysed. In January horizontal dispersion is more pronounced and vertical mixing is smaller than in July. In both cases the resulting quasi-stationary fields of the mass mixing ratio display a pronounced zonal asymmetry. The variability accounts up to 30% of the mean field.
Ozone depletion in the plume of a solid-fuelled rocket
Authors: Krüger B. C.
Published: April 2005

Abstract. The local effects of the emission of a solid-fuelled rocket on the stratospheric ozone concentration have been investigated by photochemical model calculations. A one-dimensional horizontal model has been applied which calculates the trace gas composition at a single atmospheric altitude spatially resolved around the exhaust plume. Different cases were tested for the emissions of the Space Shuttle concerning the composition of the exhaust and the effects of heterogeneous reactions on atmospheric background aerosol. The strongest depletion of ozone is achieved when a high amount of the emitted chlorine is Cl2. If it is purely HCl, the effect is smallest, though in this case the heterogeneous reactions show their largest influence. From the results it may be estimated whether ozone depletion caused by rocket launches can be detected by satellite instruments. It appears that the chance of coincidental detection of such an event is rather small.
Coupling phases and amplitudes of minor constituents with temperature perturbations in the lower thermosphere
Authors: Chen Y. W. , Xiao F. L.
Published: April 2005

Abstract. Based on the linearized theory of atmospheric gravity waves (AGW) and considering the effects of temperature perturbation on the chemical rate coefficients, the formulae of coupling relations between nj/nj and T'/T driven by AGW (nj and T denote the background quantities) are described, the coupling phases and amplitudes of minor constituents O3, NO, H, OH, and O are analyzed in detail for the mesopause (86 km) and just upside of the O layer (100 km) at daytime. A general principle is outlined: the coupling phases are strongly dependent on density scale heights and perturbation scales, while the amplitudes are little affected by these two factors. A criterion to distinguish the coupling behaviour is given: when the minor constituent number density scale height Hj satisfies 1-γHm/Hj>0 (Hm denotes the scale height of the major constituent), the dynamical perturbation process always keeps the nj/nj in phase with T'/T, i.e. keeps the nj/nj in antiphase with that of the major constituent. The results obtained indicate that both the temperature dependence of reaction rate coefficients and the profile slopes of the O distribution may have a major influence on the behaviour of the coupling relations.