Recent Flare Research Articles

MONITORING SUPERGIANT FAST X-RAY TRANSIENTS WITHSWIFT. III. OUTBURSTS OF THE PROTOTYPICAL SUPERGIANT FAST X-RAY TRANSIENTS IGR J17544-2619 AND XTE J1739-302

IGR J17544-2619 and XTE J1739-302 are considered the prototypical sources of the new class of High Mass X-ray Binaries, the Supergiant Fast X-ray Transients (SFXTs).These sources were observed during bright outbursts on 2008 March 31 and 2008 April 8, respectively, thanks to an on-going monitoring campaign we are performing with Swift, started in October 2007. Simultaneous observations with XRT and BAT allowed us to perform for the first time a broad band spectroscopy of their outbursts. The X-ray emission is well reproduced with absorbed cutoff powerlaws, similar to the typical spectral shape from accreting pulsars. IGR J17544-2619 shows a significantly harder spectrum during the bright flare (where a luminosity in excess of 1E36 erg/s is reached) than during the long-term low level flaring activity (1E33-1E34 erg/s), while XTE J1739-302 displayed the same spectral shape, within the uncertainties, and a higher column density during the flare than in the low level activity. The light curves of these two SFXTs during the bright flare look similar to those observed during recent flares from other two SFXTs, IGRJ11215-5952 and IGRJ16479-4514, reinforcing the connection among the members of this class of X-ray sources.

Structure function of the UV variability of Q0957+561

We present a detailed structure function analysis of the UV variability of Q0957+561. From new optical observations, we constructed normalized structure functions of the quasar luminosity at restframe wavelengths of 2100 and 2600 \AA. Old optical records also allow the structure function to be obtained at 2100 \AA, but 10 years ago in the observer's frame. These three structure functions are then compared to predictions of both simple and relatively sophisticated (incorporating two independent variable components) Poissonian models. We do not find clear evidence of a chromatic mechanism of variability. From the recent data, 100-d time-symmetric and 170-d time-asymmetric flares are produced at both restframe wavelengths. Taking into account measurements of time delays and the existence of an EUV/radio jet, reverberation is probably the main mechanism of variability. Thus, two types of EUV/X-ray fluctuations would be generated within or close to the jet and later reprocessed by the disc gas in the two emission rings. The 100-d time-symmetric shots are also responsible for most of the 2100 \AA variability detected in the old experiment. However, there is no evidence of asymmetric shots in the old UV variability. If reverberation is the involved mechanism of variability, this could mean an intermittent production of high-energy asymmetric fluctuations. The old records are also consistent with the presence of very short-lifetime (10 d) symmetric flares, which may represent additional evidence of time evolution. We also discuss the quasar structure that emerges from the variability scenario.

Early effects of Anakinra in corticosteroid naïve SOJIA patients

Interleukin-1R antagonist (anakinra) induces disease remission in about 50% of corticosteroid (CS) resistant cases of systemic onset JIA (SOJIA) [1,2]. Clinicians debate whether etanercept should still be tried first before giving anakinra to such patients. Another, more chalenging, issue is to start anakinra even in CS naive SOJIA patients. We here report our first experiences of such an approach in 7 patients with SOJIA. Four patients had recent onset SOJIA (3 weeks to 3 months) with classical spiking fever, exanthema and arthritis, 3 had a recent flare. They were all treated with indomethacin for at least 2 weeks without effect. There were no signs of haemophagocytosis. Anakinra was started (2 mg/kg sc daily) as an in-patient procedure to monitor for disease progression. Disease activity was monitored at 0, 24, 72 hr and 3 weeks. Fever and exanthema disappeared within 24 hours, arthritis within 3 days. One child had a recurrence of arthritis without fever or exanthema after 2 weeks. The mean values at t = 72 hrs: CRP decreased from 178 to 33, ESR from 120 to 94, ferritin from 1260 to 375. In 3 of 5 tested NK cell function restored within 72 hr. Current follow up of 3 weeks anakinra showed persistent remission in 6/7 without the use of CS. Based on these short term results we would like to propose a RCT (PRINTO?) to define the place of anakinra with a read-out of disease activity and prednisone use.

Synchrotron Self‐Compton Analysis of TeV X‐Ray‐Selected BL Lacertae Objects

We introduce a methodology for analysis of multiwavelength data from X-ray-selected BL Lac (XBL) objects detected in the TeV regime. By assuming that the radio-through-X-ray flux from XBLs is nonthermal synchrotron radiation emitted by isotropically distributed electrons in the randomly oriented magnetic field of a relativistic blazar jet, we obtain the electron spectrum. This spectrum is then used to deduce the synchrotron self-Compton (SSC) spectrum as a function of the Doppler factor, magnetic field, and variability timescale. The variability timescale is used to infer the comoving blob radius from light-travel time arguments, leaving only two parameters. With this approach, we accurately simulate the synchrotron and SSC spectra of flaring XBLs in the Thomson through Klein-Nishina regimes. Photoabsorption by interactions with internal jet radiation and the intergalactic background light (IBL) is included. Doppler factors, magnetic fields, and absolute jet powers are obtained by fitting the H.E.S.S. and Swift data of the recent giant TeV flare observed from PKS 2155–304. For the H.E.S.S. and Swift data from 2006 July 28 and 30, respectively, Doppler factors ≳60 and absolute jet powers ≳1046 ergs s−1 are required for a synchrotron/SSC model to give a good fit to the data, for a low intensity of the IBL and a ratio of 10 times more energy in hadrons than nonthermal electrons. Fits are also made to a TeV flare observed in 2001 from Mrk 421 which require Doppler factors ≳30 and jet powers ≳1045 ergs s−1.

Modulated X-Ray Emissivity near the Stress Edge in Sagittarius A*

Sgr A* is thought to be the radiative manifestation of a ~3.6E6 Msun supermassive black hole at the Galactic center. Its mm/sub-mm spectrum and its flare emission at IR and X-ray wavelengths may be produced within the inner ten Schwarzschild radii of a hot, magnetized Keplerian flow. The lightcurve produced in this region may exhibit quasi-periodic variability. We present ray-tracing simulations to determine the general-relativistically modulated X-ray luminosity expected from plasma coupled magnetically to the rest of the disk as it spirals inwards below the innermost stable circular orbit towards the stress edge in the case of a Schwarzschild metric. The resulting lightcurve exhibits a modulation similar to that observed during a recent X-ray flare from Sgr A*.

Effective treatment of young patients with pediatric-onset, long-standing lupus nephritis with tacrolimus given as a single daily dose: an open-label pilot study

The objective of the current work is to report the preliminary experience with tacrolimus (TL) administered as a single-dose daily for maintenance therapy of young patients with pediatric-onset, long-standing systemic lupus erythematosus (SLE). Six consecutive patients with long-standing SLE were recruited for a 6-month open-label trial of single-dose-daily administration of tacrolimus (3 mg/day) without dose up of concomitantly administered prednisolone (PDN). TL treatment was started at the time of the most recent flares. Data on the clinical and serologic lupus activity were collected prospectively. The baseline characteristics of the patients were: mean age, 20 years; urinary protein/creatinine ratio, 1.22 +/- 1.94; serum C3 level, 70.8 +/- 21.2 (normal, 79-152 mg/dL); serum complement hemolytic activity (CH50), 22.2 +/- 10.3 (normal, 23-46 U/mL); serum anti-dsDNA antibody titer, 60.4 +/- 71.7 IU/mL (normal, < 12.0 IU/mL); serum creatinine, 0.55 +/- 0.11 mg/dL; European Consensus Lupus Activity Measurement (ECLAM) index, 5.2 +/- 2.6. Despite the gradual tapering of the PDN dose, marked improvement as compared with the baseline values was observed in the ECLAM index examined at one and three months and serological parameters examined at three months after the start of treatment. After a 6-months' therapy, complete response was achieved in all of the patients (serum CH50 value, 27.7 +/- 8.3 U/mL; serum anti-dsDNA antibody titer, 28.4 +/- 27.9 U/mL and the ECLAM index, 1.2 +/- 1.2 (P < 0.05), respectively), except in one patient who showed WHO class V lupus nephritis. No serious adverse effects were observed. These data suggest that TL, even when administered as a single-daily dose, is effective and safe for selected young patients with pediatric-onset, long-standing SLE. However, further studies on a larger number of patients are needed to confirm these results.

Comparison of ionospheric Total Electron Content derived from collocated GNSS receivers over HartRAO during solar X-ray flares

The International Global Navigation Satellite Systems (GNSS) and the South African ground based network of dual frequency Global Positioning System receivers provide a unique chance to monitor the space weather effects on the ionospheric total electron content (TEC) over South Africa. In particular, using the University of New Brunswick ionospheric modelling software, TEC was computed over collocated HRAO (27.69°E, 25.89°S) ASTECH X-ZII3 and HARB (27.71°E, 25.89°S) TRIMBLE 4000SSI GNSS receivers located at Hartebeesthoek for the solar X17 flare which occurred on day 301, 2003 and the recent solar X9 flare which occurred on day 339, 2006. TEC values were compared by computing the TEC differences between these stations for the two selected flares. It was found that the TEC difference between HRAO and HARB is large (~9 TECU) for the X17 flare compared to the X9 (~6 TECU). The possible reasons for the TEC difference between the two receivers could presumably be attributed to the receivers’ instrumental differences, inaccuracy associated with the single-layer ionospheric model, and inaccuracy within the geometric mapping function. Furthermore, a comparison of the TEC values over South Africa for these flares show evidence of solar cycle dependence. This is important for future application in high frequency radio communication, navigation, positioning, frequency management and long term studies of impact of solar outputs on climate change over South Africa.

Exaggerated insect bite reaction exacerbated by a pyogenic infection in a patient with chronic lymphocytic leukaemia

A 69-year-old woman with chronic lymphocytic leukaemia presented with an 18-month history of pruritic, tender, erythematous plaques. The recurrent lesions simulated insect bites and cellulitis, but failed to respond to appropriate treatments. A recent severe flare was associated with markedly elevated inflammatory markers and swelling of the left leg. The swelling settled rapidly with ibuprofen, leaving cellulitis around a small ulcer infected with Staphylococcus aureus and Streptococcus pyogenes. The cellulitis responded to oral flucloxacillin. Subsequent multiple small exaggerated insect bite reaction lesions settled with oral prednisolone. Eosinophilic cellulitis (Wells' syndrome) was considered unlikely based on the lack of a morphoea-like resolution phase, histological lack of flame figures and presence of vasculitis; however, the distinction is probably artificial.

Biological effects of gamma-ray bursts: distances for severe damage on the biota

In this paper we present a unified, quantitative synthesis of analytical and numerical calculations of the effects that could be caused on Earth by a gamma-ray burst (GRB), considering atmospheric and biological implications. The main consequences of the illumination by a GRB are grouped into four distinct classes and analysed separately, namely: direct γ flash, UV flash, O3 layer depletion and cosmic rays. The effectiveness of each of these classes is compared and distances for significant biological damage are given for each one. We find that the first three effects have the potential to cause global environmental changes and biospheric damage, even if the source is located at galactic distances or even farther afield (up to 150 kpc, where 1 parsec=3.09×1016 m, about five times the Galactic diameter of 30 kpc). Instead, cosmic rays would only be a serious threat for close sources (of the order of a few parsecs).As a concrete application from a well-recorded event, the effects on the biosphere of an event identical to the giant flare of SGR1806-20 on 27 December 2004 have been calculated. In spite of not belonging to the so-called ‘classical’ GRBs, most of the parameters of this recent flare are quite well known and have been used as a calibration for our study. We find that a giant flare impinging on Earth is not a threat for life in all practical situations, mainly because it is not as energetic, in spite of being much more frequent than GRBs, unless the source happens to be extremely close.

Long-term mizoribine intermittent pulse therapy for young patients with flare of lupus nephritis

Mizoribine (MZR) is a novel purine synthesis inhibitor that was developed in Japan. We previously reported the efficacy and safety of oral MZR intermittent pulse therapy, which is associated with elevated peak serum MZR levels, in selected patients with lupus nephritis. However, the efficacy and safety of long-term MZR intermittent pulse therapy (administered for over 24 months) in lupus nephritis patients at high risk for relapse has not yet been reported. Our study included five patients with a long history of systemic lupus erythematosus (SLE), including four patients with proliferative lupus nephritis (WHO class IV) and one patient with WHO class II lupus nephritis, in whom remission had been achieved through treatment with high-dose corticosteroids combined with cytotoxic agents. For the most recent flares, all the patients were treated with MZR intermittent pulse therapy without increase in the dose of corticosteroids. MZR was administered at 5-10 mg/kg per day (up to 500 mg) as a single daily dose on two days of the week (Monday and Thursday) for over 24 months. Concomitantly administered corticosteroid dose was gradually reduced or continued unchanged. At presentation, the urinary protein excretion, serum complement hemolytic activity (CH50) and serum anti-dsDNA antibody titer were 1.7+/-1.0 g/day, 16.6+/-3.8 U/mL (normal, 23-46 U/mL) and 143.7+/-151.1 IU/mL (normal,<12.0 IU/mL), respectively. At the latest observation point, after a mean interval of 31 months (24-34 months) after the initiation of MZR pulse therapy, the urinary protein excretion and serum anti-dsDNA antibody titer were significantly decreased (0.3+/-0.2 g/day and 18.5+/-19.1 IU/mL, respectively; P<0.05), and the serum CH50 value had returned to within normal range (33.6+/-7.8 U/mL, P<0.05). Despite the reduced minimum dose of prednisolone required to maintain clinical remission at the time of the post-treatment evaluation after MZR pulse therapy as compared with that at the time of the pretreatment evaluation (9.0+/-4.5 vs. 17.5+/-7.9 mg/day; P=0.0656), the calculated flare rate was significantly decreased (0.15+/-0.2 vs. 0.6+/-0.11 times per year; P<0.05). The serum creatinine level remained within normal range in all the study participants. Furthermore, the platelet count increased following the MZR pulse therapy in two patients who had suffered from chronic thrombocytopenia. No serious adverse effects were observed. From the view point of the balance between suppression of disease activity and the adverse effects of treatment, we believe that long-term MZR pulse therapy may be the treatment of choice in selected patients with lupus nephritis at high risk for relapse. However, this was only a pilot study conducted on a small number of subjects, without a control group. Further studies to confirm the long-term efficacy and safety of oral MZR intermittent pulse therapy in larger numbers of patients are needed.

A Possible Rossby Wave Instability Origin for the Flares in Sagittarius A*

In recent years, near-IR and X-ray flares have been detected from the Galaxy's central radio point source, Sagittarius A* (Sgr A*), believed to be a \~3.10^6 solar masses supermassive black hole. In some cases, the transient emission appears to be modulated with a (quasi-)periodic oscillation (QPO) of ~ 17-20 minutes. The implied ~ 3 r_S size of the emitter (where r_S = 2GM/c^2 is the Schwarzschild radius) points to an instability - possibly induced by accretion - near the Marginally Stable Orbit (MSO) of a slowly spinning object. But Sgr A* is not accreting via a large, 'standard' disk; instead, the low density environment surrounding it apparently feeds the black hole with low angular momentum clumps of plasma that circularize within ~ 10-300 r_S and merge onto a compact, hot disk. In this Letter, we follow the evolution of the disk following such an event, and show that a Rossby wave instability, particularly in its magnetohydrodynamic (MHD) form, grows rapidly and produces a period of enhanced accretion lasting several hours. Both the amplitude of this response, and its duration, match the observed flare characteristics rather well.

Electron Acceleration at Reconnecting X‐Points in Solar Flares

The acceleration of electrons in solar flares is simulated using an extended version of a full orbit test-particle code previously used to compute losses of fusion alpha particles from tokamaks and to study flare proton acceleration. The magnetic and electric fields in the model are obtained from solutions of the linearized MHD equations for reconnecting modes at a magnetic X-point with zero equilibrium current. The magnetic field is assumed to have a small finite component perpendicular to the plane of the X-point. The version of the code used in the simulations is fully relativistic and includes Coulomb collisions. It is demonstrated that electrons cross the system boundary at distinct footpoints with the relative numbers and energy distribution at each footpoint sensitive to the longitudinal magnetic field component and collision time. These results are discussed in the context of recent flare observations showing asymmetric hard X-ray emission from the chromospheric footpoints of magnetic loops.

A serum proteomic approach to gauging the state of remission in Wegener's granulomatosis

To identify serum ion patterns that distinguish remission from active disease in patients with Wegener's granulomatosis (WG). Using sera collected in the WG Etanercept Trial, we selected samples from patients who either were undergoing a period of extended disease remission or had recent flares of active WG. Unfractionated samples were randomized into sets for training and testing, such that remission sera and active disease sera could be analyzed without batch bias. Molecular species within the sera were ionized by high-resolution, matrix-assisted laser desorption ionization time-of-flight mass spectrometry. We then used a bioinformatics pattern-recognition tool to identify optimal combinations of ions. During the training stage, the clinical data (remission versus active disease) were provided in association with the spectral data from each sample. In the testing stage, we performed blinded testing on a previously unexamined set of samples. The most robust model, trained on a total of 82 samples (42 remission, 40 active disease), included 7 key ions with mass:charge ratios of 803.239, 2,171.672, 2,790.574, 3,085.237, 5,051.726, 5,833.989, and 6,630.465. The combined relative amplitudes of these 7 ions identified 5 distinct clusters of either remission or active disease samples during the training stage. In the testing stage, this model segregated 72 samples into the same 5 clusters, including 1 large remission cluster (n = 28) and another large active disease cluster (n = 32). Three smaller clusters of active disease or remission samples were also identified, with remission clusters populated by 2 samples in one cluster and 8 in another, and an active disease cluster populated by 2 samples. The model categorized 35 of 37 remission samples correctly (sensitivity 95%, 95% confidence interval [95% CI] 82.1-99.4) and 32 of 35 active disease samples correctly (specificity 91%, 95% CI 78.1-98.1). This serum proteomic profiling approach appears to be useful in distinguishing between states of stable clinical remission and active disease. Further validation and refinement of this strategy may help clinicians apply immunosuppressive therapies more judiciously among their patients, thereby avoiding morbidity and mortality from excessive treatment. Identification of the most robust and clinically useful combinations of ions will permit the rational selection of molecules for sequencing and analysis.

Quiescent Radio Emission from Southern Late‐Type M Dwarfs and a Spectacular Radio Flare from the M8 Dwarf DENIS 1048−3956

We report the results of a radio monitoring program conducted at the Australia Telescope Compact Array to search for quiescent and flaring emission from seven nearby Southern late-type M and L dwarfs. Two late-type M dwarfs, the M7 V LHS 3003 and the M8 V DENIS 1048-3956, were detected in quiescent emission at 4.80 GHz. The observed emission is consistent with optically thin gyrosynchrotron emission from mildly relativistic (~1-10 keV) electrons with source densities ne 109 cm-3 in B 10 G magnetic fields. DENIS 1048-3956 was also detected in two spectacular, short-lived flares, one at 4.80 GHz (peak fν = 6.0 ± 0.8 mJy) and one at 8.64 GHz (peak fν = 29.6 ± 1.0 mJy) approximately 10 minutes later. The high brightness temperature (TB 1013 K), short emission period (~4-5 minutes), high circular polarization (~100%), and apparently narrow spectral bandwidth of these events imply a coherent emission process in a region of high electron density (ne ~ 1011-1012 cm-3) and magnetic field strength (B ~ 1 kG). If the two flare events are related, the apparent frequency drift in the emission suggests that the emitting source either moved into regions of higher electron or magnetic flux density or was compressed, e.g., by twisting field lines or gas motions. This emission may be related to a recent optical flare from this source that exhibited indications of chromospheric mass motion. The quiescent fluxes from the radio-emitting M dwarfs are too bright to support the Gudel-Benz empirical radio/X-ray relations, confirming a trend previously noted by Berger et al. The violation of these relations is symptomatic of a divergence in magnetic emission trends at and beyond spectral type M7/M8, where relative X-ray and Hα emission drops precipitously while relative radio emission appears to remain constant or possibly increases. With an apparent decline in chromospheric/coronal heating, the origin of hot coronal plasmas around ultracool dwarfs remains uncertain, although external sources, such as accretion from a residual disk or tidally distorted companions, remain possibilities worth exploring.

Les fantômes de la Serbie

After the removal of the dictator Slobodan Milosevic, a glimmer of hope was born in Belgrade, in the rest of the former Yugoslavia and in the entire Balkan region. But this democracy in making has not been able to surmount a number of obstacles. The recent flare up in Kosovo is the latest avatar.

O perfil da antiestreptolisina O no diagnóstico da febre reumática aguda

OBJETIVO: estabelecer o perfil dos títulos de ASO, mediante o diagnóstico diferencial da FRA com outras afecções que também cursam com níveis elevados de ASO. MÉTODOS: foram estudados 78 casos de FRA na apresentação e seguimento, 22 de coréia isolada, 45 de infecções orofaringeanas recorrentes (IOR) e 23 de artrites idiopáticas juvenis (AIJ), com início ou reativação recente. A determinação seqüencial de ASO (UI/ml) foi realizada por ensaio nefelométrico automatizado (Behring®-Germany) nos períodos de 0-7 dias, 1-2 semanas, 2-4 semanas, 1-2 meses, 2-4 meses, 4-6 meses, 6-12 meses, 1-2 anos, 2-3 anos, 3-4 anos e 4-5 anos após o diagnóstico. RESULTADOS: os títulos de ASO na fase aguda da FRA apresentaram elevação significante até o intervalo de 2- 4 meses (p < 0,0001), quando atingiram os níveis basais e permaneceram estáveis por 5 anos na vigência de profilaxia secundária com penicilina. Os valores de ASO na apresentação da FRA também foram mais elevados e com diferença significante quando comparados aos de coréia isolada, IOR e AIJ (p = 0,0025). As variações etárias e o limite superior da normalidade (320 UI/ml) foram considerados para a comparação entre estes grupos, assim como para o cálculo da sensibilidade (73,3%) e da especificidade (57,6%) mediante o diagnóstico clínico de FRA. A especificidade e valor preditivo positivo do teste aumentaram com títulos crescentes, sendo mais alta com títulos > 960 UI/ml. CONCLUSÃO: esta reavaliação do perfil da ASO indicou uma resposta exuberante na fase aguda da febre reumática indicou ainda que os seus níveis séricos podem diferenciá-la de outras afecções que também cursam com níveis elevados de ASO, como as infecções orofaringeanas recorrentes ou as artrites idiopáticas juvenis em atividade.

Antistreptolysin O titer profile in acute rheumatic fever diagnosis

OBJECTIVE: To determine ASO titer profile by establishing ARF differential diagnoses of other diseases with high levels of ASO antibodies. METHODS: We investigated 78 patients with ARF at onset and follow-up, 22 with isolated chorea at onset, 45 with recurrent oropharyngeal tonsillitis, and 23 with recent flare of juvenile idiopathic arthritis. We tested ASO with automated particle-enhanced immunonephelometric assay (Behring(R)-Germany). The ASO (IU/ml) titers were assessed at the following time intervals: 0-7 days, 1-2 weeks, 2-4 weeks, 1-2 months, 2-4 months, 4-6 months, 6-12 months, 1-2 years, 2-3 years, 3-4 years, and 4-5 years after onset of ARF. RESULTS: ASO titers in patients diagnosed with ARF had a significant increase up to the 2-4-month time interval (P<0.0001). Baseline levels were observed afterwards in patients under regular penicillin prophylaxis. The levels of ASO in ARF were also significantly higher than in patients with isolated chorea, recurrent oropharyngeal infections or juvenile idiopathic arthritis (P=0.0025), when age-matched samples of these groups were compared. The testacute;s sensitivity was 73.3% and the specificity was 57.6%, and it was calculated taking into account the upper limit of normality at 320 IU/ml, as well as the established diagnosis of ARF. The testacute;s specificity and positive predictive value increased with rising or higher titers, being higher with titers above 960 UI/ml. CONCLUSION: This reappraisal of ASO profile in ARF patients indicates a remarkable response during the acute phase, and that points to the extent to which ASO levels may differentiate ARF from other diseases with high levels of ASO antibodies, as coincidental but unrelated streptococcal infection or chronic arthritis flareup.

Pitfalls in interpretation: calcium that's not bone.

This is a 65-yr-old woman with dermatomyositis and extensive calcinosis. On physical examination subcutaneous nodules were widely distributed on her chest and extremities. Her current CPK is 163 IU/L (normal range 0-175); however, with a recent flare of her symptoms, the CPK peaked at 411 IU/L. Her current medications are Imuran 25 mg/d, Prednisone 4 mg/d, and conjugated equine estrogen 0.625 mg/d.

A model of impulsive loop flares revisited

A critical examination of the components of the recent impulsive loop flare model of Takakura is made. It is found that his analysis of the stability of the electron distribution resulting from anomalous heat conduction is in error and electron plasma waves would not be excited. Rather, in the regions where the electron/proton temperature ratioT e/T i ≲ 10, electrostatic ion-cyclotron waves would be excited and in the regions whereT e ≳ 10, ion-acoustic waves would be excited. Ratios ofT e/T i ≳ 10 occur only in the late time development behind the conduction fronts. Since the anomalous resistivity due to electrostatic ion-cyclotron waves is fortuitously about 70% of the one used by Takakura, the general development will follow closely the one calculated by him. Because the anomalous resistivity due to ion-acoustic waves is about 95 times the one used by Takakura, the development in the parts of the loop whereT e/T i ≳ 10 for late times would be altered considerably.

Radiation exposure predictions for short-duration stay Mars missions

The human radiation environment for several short-duration stay manned Mars missions is predicted using the Mission Radiation Calculation (MIRACAL) program, which was developed at NASA Langley Research Center. This program provides dose estimates for galactic cosmic rays (GCR) and large and ordinary solar proton flare events for various amounts of effective spacecraft shielding (both operational and storm shelter thicknesses) and a given time history of the spacecraft's heliocentric position. The results of this study show that most of the missions can survive the most recent large flares (if they were to occur at the missions' perihelion) if a 25 g/cm2 storm shelter is assumed. The dose predictions show that missions during solar minima (when solar flare activity is the lowest) are not necessarily the minimum dose cases, due to increased GCR contribution during this time period. The direct transfer mission studied has slightly lower doses than the outbound Venus swingby mission [on the order of 10-20 centi-Sieverts (cSv) lower], with the greatest dose differences for the assumed worst case scenario (when the large flares occur at perihelion). The GCR dose for a mission can be reduced by having the crew spend some fraction of its day nominally in the storm shelter (other than during flare events).