Characteristic Dependence of Umbral Dots on their Magnetic Structure

Umbral dots (UDs) were observed in a stable sunspot in NOAA 10944 by the Hinode Solar Optical Telescope on 2007 March 1. The observation program consisted of blue continuum images and spectropolarimetric profiles of Fe I 630 nm line. An automatic detection algorithm for UDs was applied to the 2-hour continuous blue continuum images, and using the obtained data, the lifetime, size, and proper motion of UDs were calculated. The magnetic structure of the sunspot was derived through the inversion of the spectropolarimetric profiles. We calculated the correlations between UD's parameters (size, lifetime, occurrence rate, proper motion) and magnetic fields (field strength, inclination, azimuth), and obtained the following results: (1) Both the lifetime and size of UDs are almost constant regardless of the magnetic field strength at their emergence site. (2) The speed of UDs increases as the field inclination angle at their emergence site gets larger. (3) The direction of movement of UDs is nearly parallel to the direction of the horizontal component of magnetic field in the region with strongly inclined field, while UDs in the region with weakly inclined field show virtually no proper motion. Our results describe the basic properties of magnetoconvection in sunspots. We will discuss our results in comparison to recent MHD simulations by Schussler & Vogler (2006) and Rempel et al. (2009).Comment: 22 pages, 10 figures, accepted for publication in Ap

Properties of Umbral Dots as Measured from the New Solar Telescope Data and MHD Simulations

We studied bright umbral dots (UDs) detected in a moderate size sunspot and compared their statistical properties to recent MHD models. The study is based on high resolution data recorded by the New Solar Telescope at the Big Bear Solar Observatory and 3D MHD simulations of sunspots. Observed UDs, living longer than 150 s, were detected and tracked in a 46 min long data set, using an automatic detection code. Total 1553 (620) UDs were detected in the photospheric (low chromospheric) data. Our main findings are: i) none of the analyzed UDs is precisely circular, ii) the diameter-intensity relationship only holds in bright umbral areas, and iii) UD velocities are inversely related to their lifetime. While nearly all photospheric UDs can be identified in the low chromospheric images, some small closely spaced UDs appear in the low chromosphere as a single cluster. Slow moving and long living UDs seem to exist in both the low chromosphere and photosphere, while fast moving and short living UDs are mainly detected in the photospheric images. Comparison to the 3D MHD simulations showed that both types of UDs display, on average, very similar statistical characteristics. However, i) the average number of observed UDs per unit area is smaller than that of the model UDs, and ii) on average, the diameter of model UDs is slightly larger than that of observed ones.Comment: Accepted by the AP

Magnetic helicity transported by flux emergence and shuffling motions in Solar Active Region NOAA 10930

We present a new methodology which can determine magnetic helicity transport by the passage of helical magnetic field lines from sub-photosphere and the shuffling motions of foot-points of preexisting coronal field lines separately. It is well known that only the velocity component which is perpendicular to the magnetic field ($\upsilon_{\perp B}$) has contribution to the helicity accumulation. Here, we demonstrate that $\upsilon_{\perp B}$ can be deduced from horizontal motion and vector magnetograms, under a simple relation of $\upsilon_t = \mu_t + \frac{\upsilon_n}{B_n} B_t$ as suggested by D$\acute{e}$moulin & Berger (2003). Then after dividing $\upsilon_{\perp B}$ into two components, as one is tangential and the other is normal to the solar surface, we can determine both terms of helicity transport. Active region (AR) NOAA 10930 is analyzed as an example during its solar disk center passage by using data obtained by the Spectro-Polarimeter and the Narrowband Filter Imager of Solar Optical Telescope on board Hinode. We find that in our calculation, the helicity injection by flux emergence and shuffling motions have the same sign. During the period we studied, the main contribution of helicity accumulation comes from the flux emergence effect, while the dynamic transient evolution comes from the shuffling motions effect. Our observational results further indicate that for this AR, the apparent rotational motion in the following sunspot is the real shuffling motions on solar surface

Chromospheric Anemone Jets as Evidence of Ubiquitous Reconnection

The heating of the solar chromosphere and corona is a long-standing puzzle in solar physics. Hinode observations show the ubiquitous presence of chromospheric anemone jets outside sunspots in active regions. They are typically 3 to 7 arc seconds = 2000 to 5000 kilometers long and 0.2 to 0.4 arc second = 150 to 300 kilometers wide, and their velocity is 10 to 20 kilometers per second. These small jets have an inverted Y-shape, similar to the shape of x-ray anemone jets in the corona. These features imply that magnetic reconnection similar to that in the corona is occurring at a much smaller spatial scale throughout the chromosphere and suggest that the heating of the solar chromosphere and corona may be related to small-scale ubiquitous reconnection.Comment: 10 pages, 5 figure

The knowledge and expectations of parents about the role of antibiotic treatment in upper respiratory tract infection – a survey among parents attending the primary physician with their sick child

BACKGROUND: Upper respiratory tract infections (URTI) are common. The etiologic factor is usually viral, but many physicians prescribe antibiotics. We aimed to evaluate parents' expectations of and knowledge about the role of antibiotics in childhood URTI. METHODS: The study was conducted in thirteen primary care pediatric clinics. Parents of children aged 3 months to 6 years who attended with URTI symptoms were included when it was the first attendance in the current illness. Questionnaire about the current illness, reasons for attending and expectations from the visit, knowledge about URTI was filled before the visit. RESULTS: In 122 visits the average age was 2.8 ± 1.9 years. The main reasons for the visit were to avoid complications (81%) and to be examined (78%). Expected treatment was: cough suppressants (64%), anti-congestants (57%), paracetamol (56%), natural remedies (53%) and antibiotics (25%). In 28% the child had received antibiotics in past URTI. Only 37% thought that antibiotics would not help in URTI and 27% knew that URTI is a self-limited disease. 61% knew that URTI is a viral disease. Younger parental age and higher education were associated with lower expectations to receive antibiotics (p = 0.01, p < 0.005 respectively). While previous antibiotic treatment (p < 0.001), past perceived complications (p = 0.05) and the thought that antibiotics help in URTI (p < 0.001) were associated with a greater expectation for antibiotics. CONCLUSIONS: A quarter of the parents attending the physician with URTI are expecting to get antibiotics. Predictors were lower education, older parental age, receiving antibiotics in the past and the belief that antibiotics help in URTI

IFNβ Protects Neurons from Damage in a Murine Model of HIV-1 Associated Brain Injury.

Infection with human immunodeficiency virus-1 (HIV-1) causes brain injury. Type I interferons (IFNα/β) are critical mediators of any anti-viral immune response and IFNβ has been implicated in the temporary control of lentiviral infection in the brain. Here we show that transgenic mice expressing HIV-1 envelope glycoprotein 120 in their central nervous system (HIVgp120tg) mount a transient IFNβ response and provide evidence that IFNβ confers neuronal protection against HIVgp120 toxicity. In cerebrocortical cell cultures, neuroprotection by IFNβ against gp120 toxicity is dependent on IFNα receptor 1 (IFNAR1) and the β-chemokine CCL4, as IFNAR1 deficiency and neutralizing antibodies against CCL4, respectively, abolish the neuroprotective effects. We find in vivo that IFNβ mRNA is significantly increased in HIVgp120tg brains at 1.5, but not 3 or 6 months of age. However, a four-week intranasal IFNβ treatment of HIVgp120tg mice starting at 3.5 months of age increases expression of CCL4 and concomitantly protects neuronal dendrites and pre-synaptic terminals in cortex and hippocampus from gp120-induced damage. Moreover, in vivo and in vitro data suggests astrocytes are a major source of IFNβ-induced CCL4. Altogether, our results suggest exogenous IFNβ as a neuroprotective factor that has potential to ameliorate in vivo HIVgp120-induced brain injury

Spectro-Polarimetric Observation of an Emerging Flux Region: Triggering Mechanism of Ellerman Bombs

High spatial resolution observation of an emerging flux region (EFR) was done using a vector magnetograph and a H-alpha Lyot filtergraph with Domeless Solar Telescope at Hida Observatory on October 22, 2006. In H-alpha wing images, we could see many Ellerman bombs (EBs) in the EFR. Two observation modes, slit scan and slit fixed, were performed with the vector magnetograph, along with H-alpha filtergraph. Using H-alpha wing images, we detected 12 EBs during slit scan observation period and 9 EBs during slit fixed observation period. With slit scan observation, we found that all the EBs were distributed in the area where the spatial gradient of vertical field intensity was large, which indicates the possibility of rapid topological change in magnetic field in the area of EBs. With slit fixed observation, we found that EBs were distributed in the areas of undulatory magnetic fields, both in vertical and horizontal components. This paper is the first to report the undulatory pattern in horizontal components of magnetic field, which is also evidence for emerging magnetic flux by Parker instability. These results allow us to confirm the association between EBs and emerging flux tubes. Three triggering mechanism of EBs is discussed with respect to emerging flux tubes: 9 out of 21 EBs occurred at the footpoints of emerging flux tubes, 8 out of 21 EBs occurred at the top of emerging flux tubes, and 4 out of 21 EBs occurred at unipolar region. Each case can be explained by magnetic reconnection in the low chromosphere.Comment: 30 pages, 17 figure

Evolution and Flare Activity of Delta-Sunspots in Cycle 23

The emergence and magnetic evolution of solar active regions (ARs) of beta-gamma-delta type, which are known to be highly flare-productive, were studied with the SOHO/MDI data in Cycle 23. We selected 31 ARs that can be observed from their birth phase, as unbiased samples for our study. From the analysis of the magnetic topology (twist and writhe), we obtained the following results. i) Emerging beta-gamma-delta ARs can be classified into three topological types as "quasi-beta", "writhed" and "top-to-top". ii) Among them, the "writhed" and "top-to-top" types tend to show high flare activity. iii) As the signs of twist and writhe agree with each other in most cases of the "writhed" type (12 cases out of 13), we propose a magnetic model in which the emerging flux regions in a beta-gamma-delta AR are not separated but united as a single structure below the solar surface. iv) Almost all the "writhed"-type ARs have downward knotted structures in the mid portion of the magnetic flux tube. This, we believe, is the essential property of beta-gamma-delta ARs. v) The flare activity of beta-gamma-delta ARs is highly correlated not only with the sunspot area but also with the magnetic complexity. vi) We suggest that there is a possible scaling-law between the flare index and the maximum umbral area

Primary care follow up of patients discharged from the emergency department: a retrospective study

BACKGROUND: The visit to the emergency department (ED) constitutes a brief, yet an important point in the continuum of medical care. The aim of our study was to evaluate the continuity of care of adult ED visitors. METHODS: We retrospectively reviewed all ED discharge summaries for over a month 's period. The ED chart, referral letter and the patient's primary care file were reviewed. Data collected included: age, gender, date and hour of ED visit, documentation of ED referral and ED discharge letter in the primary care file. RESULTS: 359 visits were eligible for the study. 192 (53.5%) of the patients were women, average age 54.1 ± 18.7 years (mean ± SD). 214 (59.6%) of the visits were during working hours of primary care clinics ("working hours"), while the rest were "out of hours" visits. Only 196 (54.6%) of patients had a referral letter, usually from their family physician. A third (71/214) of "working hours" visits were self referrals, the rate rose to 63.5% (92/145) of "out of hours" visits (p < 0.0001). The ED discharge letter was found in 50% (179/359) of the primary care files. A follow-up visit was documented in only 31% (111/359). Neither follow up visit nor discharge letter were found in 43% of the files (153/359). CONCLUSIONS: We have found a high rate of ED self referrals throughout the day together with low documentation rates of ED visits in the primary care charts. Our findings point to a poor continuity of care of ED attendees

Temporal Evolution of Velocity and Magnetic Field in and around Umbral Dots

We study the temporal evolution of umbral dots (UDs) using measurements from the CRISP imaging spectropolarimeter at the Swedish 1-m Solar Telescope. Scans of the magnetically sensitive 630 nm iron lines were performed under stable atmospheric conditions for 71 min with a cadence of 63 s. These observations allow us to investigate the magnetic field and velocity in and around UDs at a resolution approaching 0.13". From the analysis of 339 UDs, we draw the following conclusions: (1)UDs show clear hints of upflows, as predicted by magnetohydrodynamic (MHD) simulations. By contrast, we could not find systematic downflow signals. Only in very deep layers we detect localized downflows around UDs, but they do not persist in time. (2) We confirm that UDs exhibit weaker and more inclined fields than their surroundings, as reported previously. However, UDs that have strong fields above 2000 G or are in the decay phase show enhanced and more vertical fields. (3)There are enhanced fields at the migration front of UDs detached from penumbral grains, as if their motion were impeded by the ambient field. (4) Long-lived UDs travel longer distances with slower proper motions. Our results appear to confirm some aspects of recent numerical simulations of magnetoconvection in the umbra (e.g., the existence of upflows in UDs), but not others (e.g., the systematic weakening of the magnetic field at the position of UDs.)Comment: 27 pages, 26 figures, accepted for publication in the Astrophysical Journa