Coalescence of Macroscopic Flux Ropes at the Subsolar Magnetopause: Magnetospheric Multiscale Observations

We report unambiguous in situ observation of the coalescence of macroscopic flux ropes by the magnetospheric multiscale (MMS) mission. Two coalescing flux ropes with sizes of ∼1  R_{E} were identified at the subsolar magnetopause by the occurrence of an asymmetric quadrupolar signature in the normal component of the magnetic field measured by the MMS spacecraft. An electron diffusion region (EDR) with a width of four local electron inertial lengths was embedded within the merging current sheet. The EDR was characterized by an intense parallel electric field, significant energy dissipation, and suprathermal electrons. Although the electrons were organized by a large guide field, the small observed electron pressure nongyrotropy may be sufficient to support a significant fraction of the parallel electric field within the EDR. Since the flux ropes are observed in the exhaust region, we suggest that secondary EDRs are formed further downstream of the primary reconnection line between the magnetosheath and magnetospheric fields.

Magnetospheric Multiscale Satellites Observations of Parallel Electric Fields Associated with Magnetic Reconnection

We report observations from the Magnetospheric Multiscale satellites of parallel electric fields (E_{∥}) associated with magnetic reconnection in the subsolar region of the Earth's magnetopause. E_{∥} events near the electron diffusion region have amplitudes on the order of 100  mV/m, which are significantly larger than those predicted for an antiparallel reconnection electric field. This Letter addresses specific types of E_{∥} events, which appear as large-amplitude, near unipolar spikes that are associated with tangled, reconnected magnetic fields. These E_{∥} events are primarily in or near a current layer near the separatrix and are interpreted to be double layers that may be responsible for secondary reconnection in tangled magnetic fields or flux ropes. These results are telling of the three-dimensional nature of magnetopause reconnection and indicate that magnetopause reconnection may be often patchy and/or drive turbulence along the separatrix that results in flux ropes and/or tangled magnetic fields.

Electron-scale measurements of magnetic reconnection in space

Magnetic reconnection is a fundamental physical process in plasmas whereby stored magnetic energy is converted into heat and kinetic energy of charged particles. Reconnection occurs in many astrophysical plasma environments and in laboratory plasmas. Using measurements with very high time resolution, NASA's Magnetospheric Multiscale (MMS) mission has found direct evidence for electron demagnetization and acceleration at sites along the sunward boundary of Earth's magnetosphere where the interplanetary magnetic field reconnects with the terrestrial magnetic field. We have (i) observed the conversion of magnetic energy to particle energy; (ii) measured the electric field and current, which together cause the dissipation of magnetic energy; and (iii) identified the electron population that carries the current as a result of demagnetization and acceleration within the reconnection diffusion/dissipation region.

Impact of cefaclor on the normal human oropharyngeal and intestinal microflora

Cefaclor was given orally in doses of 250 mg every 8 h for 7 days to 10 volunteers. Saliva and faecal specimens were taken up to 16 days for cultivation of aerobic and anaerobic microorganisms and for assay of cefaclor. Cefaclor was not detected in saliva or faeces. In the oropharynx only minor changes in the anaerobic part of the microflora were observed. The microflora was normalized within 1 week after the administration of cefaclor had stopped. The aerobic intestinal microflora was unchanged during and after cefaclor administration while a minor impact on the anaerobic intestinal microflora was observed. The anaerobic intestinal flora returned to its normal state within 1 week. No new colonization with cefaclor resistant microorganisms were observed and no side effects were registered during the investigation period.

Antibody responses to Epstein-Barr virus-determined nuclear antigen (EBNA)-1 and EBNA-2 in acute and chronic Epstein-Barr virus infection

Five distinct Epstein-Barr virus (EBV)-determined nuclear antigens (EBNA-1 to EBNA-5) were recently identified. Antibody responses to these antigens could conceivably differ, and thus prove of serodiagnostic value, in EBV-associated disease processes. As a first step, murine or human cell lines transfected with appropriate EBV DNA fragments and stably expressing either EBNA-1 or EBNA-2 were used to determine the frequency and time of emergence of antibodies to these two antigens in the course of acute and chronic infectious mononucleosis (IM) and to assess their titers in so-called chronic active EBV infections. Following IM, antibodies to EBNA-2 arose first and, after reaching peak titers, declined again in time to lower persistent or even nondetectable levels. Antibodies to EBNA-1 emerged several weeks or months after anti-EBNA-2 and gradually attained the titers at which they persisted indefinitely. The ratios between the anti-EBNA-1 and anti-EBNA-2 titers therefore were generally well below 1.0 during the first 6-12 months after IM and turned to well above 1.0 during the second year. In clear cases of chronic IM, the inversion of this ratio was delayed or prevented. In the less well-defined chronic EBV infections, low ratios were observed in only some of the patients. Because many of these illnesses were not ushered in by a proven IM and often showed EBV-specific antibody profiles within the normally expected range, a causal role of the virus in these cases remains doubtful.

Differences in EBV-specific antibody patterns at onset of infectious mononucleosis

The EBV-specific antibody patterns of infectious mononucleosis (IM) patients were analyzed in relation to the onset of symptoms and clinical parameters during the acute phase of the disease. The antibody patterns varied considerably on admission. Three groups of patients were identified: one had not yet attained peak antibody titers, the second was at the peak and the third had passed the peak pattern. Patients with a "peak" current pattern had significantly higher lymphocyte counts, ASAT, ALAT, serum IgG and serum IgA concentrations than patients of the third group. Unexpectedly, there was no difference between the groups with regard to duration of sore throat and general malaise before admission. It thus seems that the lymphocyte proliferation during IM closely parallels the course of the EBV-specific antibody responses, whereas the onset of IM does not closely correlate to a specific stage of the antibody pattern.

IgA antibodies to Epstein-Barr virus in infectious mononucleosis

The IgA anti-EBV (Epstein-Barr virus) response during the course of IM (infectious mononucleosis) was investigated. The IgA anti-VCA (viral capsid antigen) response was found not to be restricted to the early acute phase of the EBV infection as is the IgM anti-VCA response. Some patients with normal total serum IgA levels did not respond with measurable EBV specific IgA. These patients and those with low titers of IgA anti-VCA had shorter duration of sore throat than responders with high titers indicative of a strong correlation between the IgA anti-VCA titers and the duration of sore throat. In this way the EBV specific IgA response is unique since recent observations show that local oropharyngeal symptoms during IM appear poorly synchronized with the IgM and the IgG antibody responses. As EB virus is excreted into the oropharynx during IM, antigens are available for local EBV immunization. The results of the present study imply a possible local immunization process as a positive correlation was found between serum IgA anti-VCA and total salivary IgA.

Evidence of tinidazole interference in the oropharyngeal inflammatory process during infectious mononucleosis

The efficacy of tinidazole was studied in 24 patients with infectious mononucleosis (IM), 13 of whom were randomized for 5 days of tinidazole treatment and 11 for control without placebo. In judging the comparability of the 2 groups not only was the distribution of confounding factors such as age, sex or duration of symptoms before admission considered, but also the distribution of the Epstein-Barr virus (EBV) serological stage at entry. In these respects the groups were well matched. The duration of sore throat and pharyngotonsillitis after admission was significantly shorter for the patients treated with tinidazole than for the controls. Orosomucoid and lactodehydrogenase concentrations normalized more readily in IM patients with a short duration of sore throat after admission and in patients treated with tinidazole compared to those with a long duration of sore throat and to the tinidazole controls. Clinical and laboratory findings were thus parallel and showed a clinical effect of tinidazole, believed to be mediated via the well-known activity of this drug against anaerobic bacteria. The EBV serological stage of each patient at entry could not predict the duration of symptoms. The results showed that the course of the angina was not primarily dependent on the virus host interaction but probably on other factors, still unknown. One such factor could be the balance between the mucosal defence and the normal oropharyngeal microflora.

Low secretory IgA concentrations in oral secretions during the acute phase of infectious mononucleosis

Although the Epstein-Barr virus (EBV) relation to infectious mononucleosis (IM) has been well established, the question why IM is not compulsory during a primary EBV infection has yet to be solved. Assuming a possible oropharyngeal secretory immunoincompetence as an etiological component of IM, the secretory IgA concentrations in oral secretions during the acute phase of IM was investigated. Low concentrations of secretory IgA in IM patients (n = 18) were found, mean value 0.180 g/l as compared to those in healthy controls (n = 10), mean value 0.680 g/l. Furthermore, diminishing concentrations of secretory IgA were found during the acute phase of IM. There was no corresponding serum IgA decrease. The investigation also revealed that tinidazole, claimed to be beneficial in the treatment of anginous IM, did not affect the concentrations of spit secretory IgA.

The effect of tinidazole on primary EBV infection and immunocompetence

Tinidazole and metronidazole have been reported beneficial in the treatment of acute anginose infectious mononucleosis. As this disease is caused by the Epstein-Barr virus (EBV), the effect of tinidazole on EBV infection of human B-lymphocytes was investigated. Tinidazole had no effect on induction of EBV determined nuclear antigen (EBNA) or DNA synthesis, while immunoglobulin synthesis was increased in the presence of the drug. Cytotoxicity directed against EBV positive cell lines and long term T-lymphocyte mediated anti-EBV memory, were not affected by tinidazole. In view of these findings we suggest that tinidazole does not act directly on the primary EBV infection in vitro. Nor do our findings indicate any adverse effects of tinidazole on the virus-host relation.

The validity of four bicycle ergometer tests

The aim of this study was to compare the validity of four physical work and performance tests on bicycle ergometers commonly used in Sweden. The following four tests were compared: a) a work test of submaximal character designed for estimation of the maximal oxygen uptake of the individual (Vo2 max); b) a work test of maximal character designed for estimation of the highest work load an individual can sustain for 6 minutes (Wmax6min); c) the Cycling Strength and Endurance Test (CSET)-a performance test of maximal character consisting of a series of intermittently determined terminal thresholds; and d) a flexible work test of maximal character, the Individually Adapted Work Test (the IA-test): by a feedback mechanism the highest work load an individual can be expected to sustain for 4 minutes is determined. Criteria were cross-country runs (altogether 4) arranged a short time before and after the tests on the bicycle ergometer. Subjects were military conscripts, aged 17-25. When comparisons were made between the best prediction variable of each test, no significant differences were obtained. The size of the validity coefficients was .55-.70. However, the maximal work tests showed the highest validity coefficients. The investigation indicates that, when a work test is to be chosen, the problem, the practical conditions and the resources available should guide this choice.