ABSTRACT
In 2021 BL Lacertae underwent an extraordinary activity phase, which was intensively followed by the Whole Earth Blazar Telescope (WEBT) Collaboration. We present the WEBT optical data in ...the BVRI bands acquired at 36 observatories around the world. In mid-2021 the source showed its historical maximum, with R = 11.14. The light curves display many episodes of intraday variability, whose amplitude increases with source brightness, in agreement with a geometrical interpretation of the long-term flux behaviour. This is also supported by the long-term spectral variability, with an almost achromatic trend with brightness. In contrast, short-term variations are found to be strongly chromatic and are ascribed to energetic processes in the jet. We also analyse the optical polarimetric behaviour, finding evidence of a strong correlation between the intrinsic fast variations in flux density and those in polarization degree, with a time delay of about 13 h. This suggests a common physical origin. The overall behaviour of the source can be interpreted as the result of two mechanisms: variability on time-scales greater than several days is likely produced by orientation effects, while either shock waves propagating in the jet, or magnetic reconnection, possibly induced by kink instabilities in the jet, can explain variability on shorter time-scales. The latter scenario could also account for the appearance of quasi-periodic oscillations, with periods from a few days to a few hours, during outbursts, when the jet is more closely aligned with our line of sight and the time-scales are shortened by relativistic effects.
Blazars are active galactic nuclei (AGN) with relativistic jets whose non-thermal radiation is extremely variable on various timescales
. This variability seems mostly random, although some ...quasi-periodic oscillations (QPOs), implying systematic processes, have been reported in blazars and other AGN. QPOs with timescales of days or hours are especially rare
in AGN and their nature is highly debated, explained by emitting plasma moving helically inside the jet
, plasma instabilities
or orbital motion in an accretion disc
. Here we report results of intense optical and γ-ray flux monitoring of BL Lacertae (BL Lac) during a dramatic outburst in 2020 (ref.
). BL Lac, the prototype of a subclass of blazars
, is powered by a 1.7 × 10
M
(ref.
) black hole in an elliptical galaxy (distance = 313 megaparsecs (ref.
)). Our observations show QPOs of optical flux and linear polarization, and γ-ray flux, with cycles as short as approximately 13 h during the highest state of the outburst. The QPO properties match the expectations of current-driven kink instabilities
near a recollimation shock about 5 parsecs (pc) from the black hole in the wake of an apparent superluminal feature moving down the jet. Such a kink is apparent in a microwave Very Long Baseline Array (VLBA) image.
Context.
QSO B1420+326 is a blazar classified as a flat-spectrum radio quasar (FSRQ). At the beginning of the year 2020, it was found to be in an enhanced flux state and an extensive multiwavelength ...campaign allowed us to trace the evolution of the flare.
Aims.
We search for very high-energy (VHE) gamma-ray emission from QSO B1420+326 during this flaring state. We aim to characterize and model the broadband emission of the source over different phases of the flare.
Methods.
The source was observed with a number of instruments in radio, near-infrared, optical (including polarimetry and spectroscopy), ultraviolet, X-ray, and gamma-ray bands. We use dedicated optical spectroscopy results to estimate the accretion disk and the dust torus luminosity. We performed spectral energy distribution modeling in the framework of combined synchrotron-self-Compton and external Compton scenario in which the electron energy distribution is partially determined from acceleration and cooling processes.
Results.
During the enhanced state, the flux of both SED components of QSO B1420+326 drastically increased and the peaks were shifted to higher energies. Follow-up observations with the MAGIC telescopes led to the detection of VHE gamma-ray emission from this source, making it one of only a handful of FSRQs known in this energy range. Modeling allows us to constrain the evolution of the magnetic field and electron energy distribution in the emission region. The gamma-ray flare was accompanied by a rotation of the optical polarization vector during a low -polarization state. Also, a new superluminal radio knot contemporaneously appeared in the radio image of the jet. The optical spectroscopy shows a prominent FeII bump with flux evolving together with the continuum emission and a MgII line with varying equivalent width.
Abstract
Background
The Avon Breast Health Outreach Program (BHOP) supports community-based organizations to conduct education and outreach to link low-income and uninsured women to routine breast ...cancer screening. Women under age 40 with breast health issues may not be eligible for low-cost or free screening programs that target women age 40 and older.
Objective
Describe demographic and health characteristics of clients under age 40 served by Avon BHOP-funded organizations compared with clients of other age groups.
Methods
We analyzed CY2012 client intake data for females aged 20-75 years (N = 100,418). We conducted univariate and multivariate analysis of client demographics (race/ethnicity, annual household income, education, and geographic setting of client's residence) and health history (health insurance status, personal history of breast cancer, family history of breast cancer, prior breast biopsy, and prior mammogram). Results were stratified by age group.
Results
Overall, 5.7% (n = 5,719) of female clients were aged 20-39, 36.9% (n = 37,041) were aged 40-49, and 57.4% (57,658) were aged 50-75 years. A majority of clients (64.6%) identified as a racial and/or ethnic minority; this percentage was lowest among women under age 40 (58.8%), and highest among women aged 40-49 (69.2%). Overall, 78.4% of women reported an annual household income of $25,000 or less, with little variation across age groups. Women under age 40 were more likely to report having some college or an associate degree (27.2%) versus 21.3% of clients overall. Nearly two-thirds (64.5%) of clients reported no health insurance, with higher rates among women aged 20-39 (73.1%) and 40-49 (70.8%) compared with women aged 50 and older (59.6%). A majority of clients reported living in an urban setting (57.1%) or rural areas (31.4%); women under age 40 were more likely to report living in rural (40.8%) or frontier areas (4.6%). Current symptoms (lump, nipple discharge, rash, or unusual pain) were reported by 40.1% of women under age 40, compared with 12.0% of clients overall. Women aged 20-39 were less likely to have ever had a mammogram (34.8% versus 85.8% of all clients). However, white clients were almost twice as likely to have had a mammogram before the age of 40, even when controlling for breast symptoms and a family history of breast cancer.
Conclusion
Avon BHOP clients under age 40 were more likely to be white, to reside in rural areas, and to be uninsured despite higher levels of education. More than 40% of clients under age 40 reported current breast symptoms.
Discussion
Characteristics of Avon BHOP clients under age 40 are influenced by the location and target population of funded organizations. Low-income and uninsured women under age 40 may require specialized outreach and education to ensure timely access to breast cancer screening services.
Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-13-11.
Abstract
Background
The Avon Breast Health Outreach Program (BHOP) supports community-based organizations to conduct education and outreach to link low-income and uninsured women to routine breast ...cancer screening. These organizations capture health and demographic information for clients screened as a result of outreach using a standardized Client Intake Form (CIF). Prior research demonstrated higher rates of overall form completion for data collected via audio-computer assisted self-interview (ACASI) versus face-to-face or self-administered paper interview. Advances in tablet computer technology provide additional options and potential advantages for collecting client-level data electronically.
Objective
To determine if electronic CIF data collection via tablet is a practical alternative to paper-based data collection, and assess the relative administrative burden, advantages and disadvantages for Avon BHOP-funded organizations for each method.
Methods
English and Spanish copies of the CIF were created in iSurvey, an application developed for iPad. Currently funded grantees (n = 101) were invited to apply for the pilot; 34 of 38 applicants in 24 states were selected, with priority given to organizations with a majority of English- or Spanish-speaking clients, and greater annual client volume. Pilot sites received a tablet pre-loaded with iSurvey. Grantees received web-based training and individual technical assistance on tablet use, data collection and submission procedures. Avon BHOP staff conducted telephone follow-up to assess organizations’ feedback concerning acceptability to program staff and clients of CIF data collection using the tablet, and effects on data quality and administrative processes relative to paper CIFs. Quality assurance was conducted on all CIFs submitted via iSurvey to identify duplicate or invalid records.
Results
948 CIFs (838 English, 110 Spanish) were submitted using the tablets during a two month period from March 21 to May 21, 2013. Five organizations submitted fewer than 5 CIFs, eight did not submit any CIFs, and three organizations discontinued participation; their tablets were reassigned to different organizations. Grantees using the tablets for CIF data collection found the program easy to use and data entry efficient. Challenges reported included difficulties integrating the tablets into clinic flow, lack of familiarity with tablet technology among clients and staff, and an inability to review data for errors or completeness prior to electronic submission.
Conclusion
CIF data collection via tablet is an option for electronic data capture for some organizations. However, many organizations reported challenges in effectively integrating this new technology into existing clinic flow and administrative processes.
Discussion
While tablets are a relatively inexpensive and practical option for electronic client data collection in some settings, some organizations reported a preference for paper forms. Many of the identified administrative barriers may be resolved through the provision of technical assistance and capacity building support to grantee organizations. Future analysis may focus on the completeness of data collected via tablet versus paper.
Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-08-15.
Given that prolonged exposure to estrogen and increased telomerase activity are associated with endometrial carcinogenesis, our objective was to evaluate the interaction between the MAPK pathway and ...estrogen induction of telomerase activity in endometrial cancer cells. Estradiol (E2) induced telomerase activity and hTERT mRNA expression in the estrogen receptor (ER)-α positive, Ishikawa endometrial cancer cell line. UO126, a highly selective inhibitor of MEK1/MEK2, inhibited telomerase activity and hTERT mRNA expression induced by E2. Similar results were also found after transfection with ERK 1/2-specific siRNA. Treatment with E2 resulted in rapid phosphorylation of p44/42 MAPK and increased MAPK activity which was abolished by UO126. The hTERT promoter contains two estrogen response elements (EREs), and luciferase assays demonstrate that these EREs are activated by E2. Exposure to UO126 or ERK 1/2-specific siRNA in combination with E2 counteracted the stimulatory effect of E2 on luciferase activity from these EREs. These findings suggest that E2-induction of telomerase activity is mediated via the MAPK pathway in human endometrial cancer cells.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Most single units recorded from macaque secondary visual cortex (V2) respond with higher firing rates to synthetic texture images containing "naturalistic" higher-order statistics than to spectrally ...matched "noise" images lacking these statistics. In contrast, few single units in V1 show this property. We explored how the strength and dynamics of response vary across the different layers of visual cortex by recording multiunit (defined as high-frequency power in the local field potential) and gamma-band activity evoked by brief presentations of naturalistic and noise images in V1 and V2 of anesthetized macaque monkeys of both sexes. As previously reported, recordings in V2 showed consistently stronger responses to naturalistic texture than to spectrally matched noise. In contrast to single-unit recordings, V1 multiunit activity showed a preference for images with naturalistic statistics, and in gamma-band activity this preference was comparable across V1 and V2. Sensitivity to naturalistic image structure was strongest in the supragranular and infragranular layers of V1, but weak in granular layers, suggesting that it might reflect feedback from V2. Response timing was consistent with this idea. Visual responses appeared first in V1, followed by V2. Sensitivity to naturalistic texture emerged first in V2, followed by the supragranular and infragranular layers of V1, and finally in the granular layers of V1. Our results demonstrate laminar differences in the encoding of higher-order statistics of natural texture, and suggest that this sensitivity first arises in V2 and is fed back to modulate activity in V1.
The circuit mechanisms responsible for visual representations of intermediate complexity are largely unknown. We used a well validated set of synthetic texture stimuli to probe the temporal and laminar profile of sensitivity to the higher-order statistical structure of natural images. We found that this sensitivity emerges first and most strongly in V2 but soon after in V1. However, sensitivity in V1 is higher in the laminae (extragranular) and recording modalities (local field potential) most likely affected by V2 connections, suggesting a feedback origin. Our results show how sensitivity to naturalistic image structure emerges across time and circuitry in the early visual cortex.
Abstract
We present multi-epoch optical spectra of the
γ
-ray bright blazar 1156+295 (4C +29.45, Ton 599) obtained with the 4.3 m Lowell Discovery Telescope. During a multiwavelength outburst in late ...2017, when the
γ
-ray flux increased to 2.5 × 10
−6
phot cm
−2
s
−1
and the quasar was first detected at energies ≥100 GeV, the flux of the Mg
ii
λ
2798 emission line changed, as did that of the Fe emission complex at shorter wavelengths. These emission-line fluxes increased along with the highly polarized optical continuum flux, which is presumably synchrotron radiation from the relativistic jet, with a relative time delay of ≲2 weeks. This implies that the line-emitting clouds lie near the jet, which points almost directly toward the line of sight. The emission-line radiation from such clouds, which are located outside the canonical accretion-disk related broad-line region, may be a primary source of seed photons that are up-scattered to
γ
-ray energies by relativistic electrons in the jet.
Obesity is a significant risk factor for ovarian cancer (OC) and associated with worse outcomes for this disease. We assessed the anti-tumorigenic effects of metformin in human OC cell lines and a ...genetically engineered mouse model of high grade serous OC under obese and lean conditions. Metformin potently inhibited growth in a dose-dependent manner in all four human OC cell lines through AMPK/mTOR pathways. Treatment with metformin resulted in G1 arrest, induction of apoptosis, reduction of invasion and decreased hTERT expression. In the K18-gT
; p53
; Brca1
(KpB) mouse model, metformin inhibited tumor growth in both lean and obese mice. However, in the obese mice, metformin decreased tumor growth by 60%, whereas tumor growth was only decreased by 32% in the lean mice (p=0.003) compared to vehicle-treated mice. The ovarian tumors from obese mice had evidence of impaired mitochondrial complex 2 function and energy supplied by omega fatty acid oxidation rather than glycolysis as compared to lean mice, as assessed by metabolomic profiling. The improved efficacy of metformin in obesity corresponded with inhibition of mitochondrial complex 1 and fatty acid oxidation, and stimulation of glycolysis in only the OCs of obese
lean mice. In conclusion, metformin had anti-tumorigenic effects in OC cell lines and the KpB OC pre-clinical mouse model, with increased efficacy in obese
lean mice. Detected metabolic changes may underlie why ovarian tumors in obese mice have heightened susceptibility to metformin.
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