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Human papillomavirus (HPV) integration is a critical step in cervical cancer development; however, the oncogenic mechanism at the genome-wide transcriptional level is still poorly understood. In this study, we employed integrative analysis on multi-omics data of six HPV-positive and three HPV-negative cell lines. Through HPV integration detection, super-enhancer (SE) identification, SE-associated gene expression and extrachromosomal DNA (ecDNA) investigation, we aimed to explore the genome-wide transcriptional influence of HPV integration. We identified seven high-ranking cellular SEs generated by HPV integration in total (the HPV breakpoint-induced cellular SEs, BP-cSEs), leading to intra-chromosomal and inter-chromosomal regulation of chromosomal genes. The pathway analysis revealed that the dysregulated chromosomal genes were correlated to cancer-related pathways. Importantly, we demonstrated that BP-cSEs existed in the HPV–human hybrid ecDNAs, explaining the above transcriptional alterations. Our results suggest that HPV integration generates cellular SEs that function as ecDNA to regulate unconstrained transcription, expanding the tumorigenic mechanism of HPV integration and providing insights for developing new diagnostic and therapeutic strategies.

Binaries consisting of a hot subdwarf star and an accreting white dwarf (WD) are sources of gravitational wave radiation at low frequencies and possible progenitors of type Ia supernovae if the WD mass is large enough. Here, we report the discovery of the third binary known of this kind: it consists of a hot subdwarf O (sdO) star and a WD with an orbital period of 3.495 hours and an orbital shrinkage of 0.1 s in 6 yr. The sdO star overfills its Roche lobe and likely transfers mass to the WD via an accretion disk. From spectroscopy, we obtain an effective temperature of $T_{\mathrm{eff}}=54\,240\pm1\,840$ K and a surface gravity of $\log{g}=4.841\pm0.108$ for the sdO star. From the light curve analysis, we obtain a sdO mass of $M_{\mathrm{sdO}}=0.55$ ${\mathrm{M_{\odot}}}$ and a mass ratio of $q=M_{\mathrm{WD}}/M_{\mathrm{sdO}}=0.738\pm0.001$. Also, we estimate that the disk has a radius of $\sim 0.41R_\odot$ and a thickness of $\sim 0.18R_\odot$. The origin of this binary is probably a common envelope ejection channel, where the progenitor of the sdO star is either an RGB star or, more likely, an early AGB star; the sdO star will subsequently evolve into a WD and merge with its WD companion, likely resulting in an R CrB star. The outstanding feature in the spectrum of this object is strong Ca H&K lines, which are blueshifted by $\sim$200 km/s and likely originate from the recently ejected common envelope, and we estimated that the remnant CE material in the binary system has a density $\sim 6\times 10^{-10} {\rm g/cm^3}$., 13 pages, 15 figures, to be published in MNRAS

Here we present a catalogue of 1056 spectroscopically identified hydrogen-dominated white dwarfs (DAWDs), 34 helium-dominated white dwarfs (DBWDs) and 276 white dwarf main sequence (WDMS) binaries from the Large sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey data release 2 (DR2). 383 DAWDs, 4 DBWDs and 138 WDMSs are new identifications after cross-match with literature. There are similar to 4100 k spectra in total from DR 2. The low ratio of white dwarfs found in LAMOST is attributed to biased selection of LAMOST input catalogue and much brighter targets relative to stars observed in Sloan Digital Sky Survey. In this paper, a new DAWD selection method is adopted as a new attempt and supplement to the traditional methods. The effective temperature, surface gravity, mass, cooling age and distance of high signal-to-noise DAWDs are estimated. The peak of the mass distribution is found to be similar to 0.6 M-circle dot, which is consistent with previous work. The parameters of WDMS binaries are also provided in this paper. As the foundation of our future work, which is to identify more WDs with debris disc, WDs found in LAMOST showed a lot of potential. Interesting infrared-excess WDs will be reported in our forthcoming paper.

We develop optical and near-infrared colour-selection criteria based on the model colours of binaries consisting of a white dwarf and a main-sequence star. Using our colour-selection algorithm, we present a catalogue of 523 white dwarfmain sequence (WDMS) binaries from the spectroscopic Sloan Digital Sky Survey Data Release 7 (SDSS DR7), most of them previously identified. Among them, we identify 86 objects as new WDMS binaries. 95 WDMS candidates are also found from the photometric SDSS DR7, cross-matched with the United Kingdom Infrared Telescope (UKIRT) Infrared Sky Survey Data Release 5 (UKIDSS DR5). Based on a chi 2 minimization technique, we derive independent stellar parameters such as the effective temperatures, surface gravities, masses and distances of the white dwarfs and secondary stars and the metallicities of the secondaries. Meanwhile, we determine the cooling age via interpolation through evolutionary models for the effective temperature and surface gravity of each DA white dwarf. Distributions of these stellar parameters have been used to study both the general properties and the completeness of WDMS binaries. A comparison between the distances measured to the white dwarfs and the secondary stars shows a clear trend towards higher distances for the white dwarf component. It is found that the mean cooling age of the WDMS sample is (t) over bar cool similar to 4.2x108?yr and our sample contains at least 11?per cent old systems, which were formed about 1.0 x 109?yr ago. The new and updated WDMS binaries will improve the completeness of the catalogue of WDMS binaries.

The stability of mass transfer is important in the formation of contact binaries from detached binaries when the primaries of the initially detached binaries fill their Roche lobes. Using Eggletons stellar evolution code, we investigate the formation and the short-period limit of contact binaries by considering the effect of the instability of mass transfer. It is found that with decreasing initial primary mass from 0.89 to 0.63 M?, the range of the initial mass ratio decreases for detached binaries that experience stable mass transfer and evolve into contact. If the initial primary mass is less than 0.63 M?, detached binaries would experience dynamically unstable mass transfer when the primaries of detached binaries fill their Roche lobes. These systems would evolve into a common envelope situation and probably then to a complete merger of two components on a quite short time-scale. This results in a low mass limit at about 0.63 M? for the primary mass of contact binaries, which might be the main reason why the period distribution of contact binaries has a short limit of about 0.22 d. By comparing the theoretical period distribution of contact binaries with the observational data, it is found that the observed contact binaries are above the low mass limit for the primary mass of contact binaries and no observed contact binaries are below this limit. This suggests that the short-period limit of contact binaries can be explained by the instability of the mass transfer that occurs when the primaries of the initially detached binaries fill their Roche lobes.

Using the precise times of mid-egress of the eclipsing polar HU Aqr, we discovered that this polar is orbited by two or more giant planets. The two planets detected so far have masses of at least 5.9 and 4.5\,M_{Jup}. Their respective distances from the polar are 3.6 AU and 5.4 AU with periods of 6.54 and 11.96 years, respectively. The observed rate of period decrease derived from the downward parabolic change in O-C curve is a factor 15 larger than the value expected for gravitational radiation. This indicates that it may be only a part of a long-period cyclic variation, revealing the presence of one more planet. It is interesting to note that the two detected circumbinary planets follow the Titus-Bode law of solar planets with n=5 and 6. We estimate that another 10 years of observations will reveal the presence of the predicted third planet.

The first complete charge-coupled device (CCD) light curves in B and V passbands of a neglected contact binary system, CW Cassiopeiae (CW Cas), are presented. They were analyzed simultaneously by using the Wilson and Devinney (WD) code (1971, ApJ, 166, 605). The photometric solution indicates that CW Cas is a W-type W UMa system with a mass ratio of m(2)/m(1) = 2.234, and that it is in a marginal contact state with a contact degree of similar to 6.5% and a relatively large temperature difference of similar to 327 K between its two components. Based on the minimum times collected from the literature, together with the new ones obtained in this study, the orbital period changes of CW Cas were investigated in detail. It was found that a periodical variation overlaps with a secular period decrease in its orbital period. The long-term period decrease with a rate of dP/dt = 3.44 x 10(-8)d yr(-1) can be interpreted either. by mass transfer from the more-massive component to the less-massive with a rate of dm(2)/dt = 3.6 x 10(-8) M(circle dot) yr(-1), or by mass and angular-momentum losses through magnetic braking clue to a magnetic stellar wind. A low-amplitude cyclic variation with a period of T = 63.7 yr might be caused by the light-time effect due to the presence of a third body.

Detections of Jupiter-like giant planets in orbit around short-period white dwarf binaries should provide insight into the formation and evolution of circumbinary planets (planets orbiting both components of short-period binaries), as well as into the ultimate fate of planets and the late evolutionary stage of binary stars (e.g. the evolution of the common envelope). However, to date no planets have been detected as companions to such close binaries. Here, we report the discovery of a giant planet orbiting the only known hibernating cataclysmic variable (CV), QS Vir, with a period of 7.86 yr. We analysed the variations of the orbital period of the eclipsing white dwarf-red dwarf binary, and a very small-amplitude cyclic change is found to be superimposed on a long-term period decrease. The period oscillation has the smallest amplitude among close binary stars and can be plausibly interpreted as the light-travel time effect via the presence of a third body. We found that the tertiary component is a giant planet with a mass of similar to 6.4 M(Jupiter) at a distance of similar to 4.2 astronomical units (au) from the binary. The continuous decrease is explained as angular momentum loss via magnetic braking which is driving the evolution of the hibernating CV into a normal cataclysmic binary.

Well-determined physical parameters of 130 W UMa systems have been collected from the literature. Based on these data, the evolutionary status and dynamical evolution of W UMa systems are investigated. It is found that there is no evolutionary difference between W- and A-type systems in $M-J$ diagram which is consistent with the results derived from the analysis of observed spectral type, $M-R$ and $M-L$ diagrams of W UMa systems. $M-R$ and $M-L$ diagrams of W- and A-type systems indicate that a large amount of energy should be transferred from the more massive to the less massive component so that they are not in thermal equilibrium and undergo thermal relaxation oscillation (TRO). Meanwhile, the distribution of angular momentum, together with the distribution of mass ratio, suggests that the mass ratio of the observed W UMa systems is decreased with the decrease of their total mass. This could be the result of the dynamical evolution of W UMa systems which suffer angular momentum loss (AML) and mass loss due to magnetic stellar wind (MSW). Consequently, the tidal instability forces these systems towards the lower q values and finally to fast rotating single stars., 8 pages, 5 figures, accepted for publication in MNRAS

The variations of the orbital periods of two Algol-type eclipsing binaries, T LMi and RW Mon, are presented through a detailed analysis of (O-C) diagrams. It is found that, apart from a secular decrease, several sudden jumps have occurred in the orbital periods of both binary systems: The period decrease rate was derived to be -1.12 x 10(-8) d/cycle and -1.456 x 10(-9) d/cycle for T LMi and RW Mon, respectively. Such a large rate is impossibly explained by angular momentum loss and mass loss due to magnetic stellar winds. The sudden jumps in the orbital periods of both stars might be caused by a rapid mass exchange between the circumstellar matter and binaries. At last, the evolutionary trend of the two Algol-type systems, whose periods decreased continuously, is discussed. Their evolutionary outcome might be W UMa stars.

Using evolutionary population synthesis, we present 13 refined absorption-line indices defined by the Lick Observatory Image Dissector Scanner (Lick/IDS) system for an extensive set of instantaneous-burst binary stellar populations (BSPs) at high resolution (∼0.3 Å), and 38 indices at intermediate resolution (3 Å). The ages of the populations are at an interval of 1 Gyr in the range 1–15 Gyr, and the metallicities are in the range 0.004–0.03. These indices are obtained by two methods: (i) using the empirical fitting functions (FFs method); (ii) measured directly from the synthetic spectra (DC method). Together with our previous paper, a data base of Lick/IDS spectral absorption-line indices for BSPs at high and intermediate resolutions is provided. This set of indices includes 21 indices of Worthey et al., four Balmer indices defined by Worthey & Ottaviani, and 13 indices with the new passband definitions of Trager et al. The full set of synthetic indices and the integrated pseudo-continuum are listed in the Appendices, which are only available online at https://doi.org/10.1111/j.1365-2966.2006.10557.x or from our website (http://www.ast9.com/), or on request from the first author. Moreover, the full set of the integrated spectral energy distributions can be obtained from our website. We compare the synthetic Lick/IDS indices obtained by the FFs method and those by the DC method for BSPs with various metallicities, and find that the discrepancies are significant: Ca4455 (index 6), Fe4668 (8), Mgb (13), Fe5709 (17), NaD (19), TiO1 (20) and TiO2 (21, except for Z= 0.02) in the W94 system, Ca4455T (6T), C24668T (8T), NaDT (19T), TiOT1 (20T) and TiOT2 (21T, except for Z= 0.02) in the T98 system obtained by the DC method are less (bluer) than the corresponding ones obtained by the FFs method for all metallicities. Ca4227 (index 3), Fe5782 (18), Ca4227T (3T) and Fe5782T (18T) are greater at Z= 0.03 and become bluer at Z= 0.004; the Fe5709T (17T) index is less at Z= 0.03 and becomes redder at Z= 0.004 than the corresponding ones obtained by the FFs method.

Theoretical study indicates that a contact binary system would merge into a rapidly rotating single star due to tidal instability when the spin angular momentum of the system is more than a third of its orbital angular momentum. Assuming that W UMa contact binary systems rigorously comply with the Roche geometry and the dynamical stability limit is at a contact degree of about 70%, we obtain that W UMa systems might suffer Darwin's instability when their mass ratios are in a region of about 0.076--0.078 and merge into the fast-rotating stars. This suggests that the W UMa systems with mass ratio $q\leq0.076$ can not be observed. Meanwhile, we find that the observed W UMa systems with a mass ratio of about 0.077, corresponding to a contact degree of about 86% would suffer tidal instability and merge into the single fast-rotating stars. This suggests that the dynamical stability limit for the observed W UMa systems is higher than the theoretical value, implying that the observed systems have probably suffered the loss of angular momentum due to gravitational wave radiation (GR) or magnetic stellar wind (MSW).

Using EPS we present high resolution (0.3 \AA, HRes) ISEDs from 3000 to 7000 \AA and Lick/IDS absorption-line indices, for an extensive set of instantaneous burst binary stellar populations (BSPs) with binary interactions. The ages of the BSPs are in the range 1 - 15 Gyr and the metallicities are in the range 0.004 - 0.03. This HRes synthesis results can satisfy the needs of modern spectroscopic galaxy surveys, and are available on request. By comparing the synthetic continuum of BSPs at high and low resolution (LRes) we show that there is a good agreement for Z=0.02 and a tolerable disagreement for non-solar metallicity. The strength of the Balmer lines at HRes is greater than that at LRes for all metallicities. The comparison of Lick/IDS absorption-line indices at LRes and HRes, both of which are obtained by the fitting functions (FFs), shows that the discrepancies in all indices except for TiO_1 and TiO_2 are insignificant for BSPs with Z=0.004 and Z=0.02. The HRes Ca4227, Fe5015 and Mg_b indices are redder than the corresponding LRes one for BSPs with Z=0.01 and Z=0.03, this effect lowers the derived age and metallicity of the BSP. The high resolution Mg_1, Fe5709 and Fe5782 indices are bluer than those at LRes, it raises the age and metallicity. The discrepancy in these six indices is greater for BSPs with Z=0.03 in comparison to Z=0.01. At HRes we compare the Lick/IDS spectral absorption indices obtained by using the FFs with those measured directly from the synthetic spectra, and see that Ca4455, Fe4668, Mg_b and Na D indices obtained by the use of the FFs are redder for all metallicities, Fe5709 is redder at Z=0.03 and becomes to be bluer at Z=0.01 and 0.004, and other indices are bluer for all metallicities than the corresponding values measured directly from the synthetic spectra., Comment: 11 pages, 10 figures, to be published in MNRAS

In a previous paper, using Eggleton's stellar evolution code, we have discussed the structure and evolution of low-mass W Ursae Majoris (W UMa) type contact binaries with angular momentum loss owing to gravitational radiation or magnetic braking. We find that gravitational radiation is almost insignificant for cyclic evolution of low-mass W UMa type systems, and it is possible for angular momentum to be lost from W UMa systems in a magnetic stellar wind. The weaker magnetic activity shown by observations in W UMa systems is likely caused by the lower mass of the convective envelopes in these systems than in similar but non-contact binaries. The spin angular momentum cannot be neglected at any time for W UMa type systems, especially for those with extreme mass ratios. The spin angular momenta of both components are included in this paper and they are found to have a significant influence on the cyclic evolution of W UMa systems. We investigate the influence of the energy transfer on the common convective envelopes of both components in detail. We find that the mass of the convective envelope of the primary in contact evolution is slightly more than that in poor thermal contact evolution, and that the mass of the convective envelope of the secondary in contact evolution is much less than that in poor thermal contact evolution. Meanwhile, the rate of angular momentum loss of W UMa type systems is much lower than that of poor thermal contact systems. This is indeed caused by the lower masses of the convective envelopes of the components in W UMa type systems. Although the models with angular momentum loss for W UMa systems exhibit cyclic evolution, they seem to show that a W UMa system cannot continue this type of cyclic evolution indefinitely, and it might coalesce into a fast-rotating star after about 1200 cycles of evolution (about 7.0 x 10(9) yr).

A detailed study of the period and the light curve of the eclipsing binary TY Bootis is presented. Based on a study of the (O - C) curve, we have found that two periodical variations superimpose on a continuous increase (d P/dt = 6.283 x 10(-8) d yr(-1)) in its period. We compared light curves obtained by other groups, and found that the light curve of the system has changed considerably. We analyzed the physical mechanisms that underlie the variation in the period and light curve of the system, and obtained some new conclusions. The continuous increase of its orbital period is probably caused by mass transfer from the secondary to the primary, rather than an expansion of the primary due to its dynamical instability. Also, the two periodical components are probably caused by two different physical mechanisms, i.e., the light-time effect is one of the possible mechanisms, which might cause a periodical component with a longer timescale (31.5 yr), and the magnetic activity cycle is the other one, which might underlie the other periodical component with a shorter timescale (11.76 yr). The long-term variation in the light curve of the system is likely to be caused by a decrease in the light level of the primary due to starspot(s) on the primary or an expansion of the primary. Finally, the trends in the evolution of the system are discussed according to a theory of W UMa systems.

In a preceding paper, using Eggleton’s evolution code we have discussed the structure and evolution of low-mass W UMa type contact binaries without angular momentum loss (AML). The models exhibit cyclic behavior about a state of marginal contact on a thermal time-scale. Part of the time of each cycle is spent in contact and part in a semi-detached state. According to observations, W UMa systems suffer AML. We present the models of low-mass contact binaries with AML due to gravitational wave radiation (GR) or magnetic stellar wind (MSW) are presented. We find that gravitational radiation cannot prevent the cyclic evolution of W UMa systems, and the effect of gravitational radiation on the cyclic behavior of contact binary evolution is almost negligible. We also find that the most likely AML mechanism for W UMa systems is magnetic braking, and that magnetic braking effects can increase the period of the cyclic evolution, and shorten the fraction of the time spent in the poor thermal contact state exhibiting EB light curve. If W UMa stars do not undergo cyclic evolution, and their angular momentum loss is caused simultaneously by MSW of both components, we find that the value of the parameter, λ, should be taken a larger value in comparison with those derived from observations of single stars. This indicates that the AML efficiency in W UMa systems may be lowered in comparison with non-contact stars because of the less mass contained in the convective envelopes of the components in W UMa systems. If W UMa systems lose their angular momentum at a constant rate. An angular momentum rate of dlnJ dt � 1.6×10 9 yr 1 can prevent the cyclic behaviour of the model, and the model can keep in good contact with an essentially constant depth of contact.

We present integrated colours for instantaneous burst single stellar populations (SSPs) of different metallicities and investigate their colour evolution. The principal difference between this study and previous work is the adoption of stellar evolutionary models that employ, amongst other things, recent opacities and a revised equation of state (EOS), and include evolutionary processes such as convective overshooting, thermal pulses and dredge-up. The models are used in the convenient form of analytic fitting functions. In addition, we use the BaSeL model for the library of stellar spectra. This model provides an extensive low-resolution theoretical flux distribution and UBVRIJHKLM colours, which have been calibrated empirically or semi-empirically, for a wide range of stellar parameters. We calculate several sets of SSPs and explore the influence of relevant parameters on the integrated colours. The ages of the SSPs are from 0.5 to 19.5 Gyr and the metallicities range from 0.0001 to 0.03. We include a variety of prescriptions for the initial mass function (IMF) in our investigation, including different choices for the lower and upper mass cut-offs to the distribution, as well as the slope. We find that the age, the metallicity and the lower mass cut-off all play an important role in determining the integrated colours of the instantaneous burst SSPs. In particular, variations in the choice of IMF can lead to deviations of up to 0.47 mag and 2.25 mag in integrated B -V and V -K colours, respectively. Conversely, we find that altering the rate of mass loss in a stellar wind, or the choice of the upper mass cut-off to the IMF, does not have a significant effect on the results. We also investigate the discrepancies that exist between the results of various SSP studies. We compare the isochrones and the colour-temperature calibrations adopted in each of these studies, and estimate the deviations owing to the choice of stellar models, spectral library, and/or IMF. We find that the deviation arising from changes in the IMF is greater than that caused by changes to the evolutionary models or spectral calibrations utilized by each study. Therefore, the form of the IMF should be chosen with care when conducting SSP studies.

We present a detailed study of the period and light curve of the eclipsing binary AP Leo. We have investigated the period variation of the system in detail using a method proposed by Kalimeris et al. (1994a,b; AAA 061.117.039, AAA 062.117.142). The orbital period of the system exhibits a periodic variation which contains four components with different frequencies. Our result is very different from that of other investigators. We compared light curves obtained by other groups, and found that the light curve of the system has changed considerably. Based on an analysis, we investigated the physical mechanisms which may underlie the variations of the period and the light curve, and obtained some new results. We have concluded that the rapid light variation is probably caused by a pulsation of the common envelope, and that the mechanism causing the pulsation may be mass transfer between the two components, or its variation. In addition, we have found that the mass transfer and magnetic activity may simultaneously play an important role in the variations in the orbital period and the light curve of the system. The paper concludes with a discussion of the evolution of the system.

Using the evolutionary population synthesis (EPS) models with and without binary interactions (BIs), we present L_Ha, L_[OII], L_{i,UV} and L_FIR for Burst, S0, Sa-Sd and Irr galaxies, and present the calibrations of star formation rate (SFR) in terms of these diagnostics. By comparison, we find that BIs lower the SFR.vs.L_Ha and SFR.vs.L_[OII] conversion factors by ~0.2 dex. Moreover, BIs do not significantly vary the calibrations of SFR in terms of L_{i,UV}. In addition, BIs have little effect on the flux at 2800A. At last, the calibration of SFR from L_FIR is almost unaffected by BIs. This is caused by the fact that BIs almost do not affect the bolometric magnitudes of SPs. We also discuss the effects of initial mass function (IMF), gas-recycle assumption (GRA) and EPS models on these SFR calibrations. Comparing the results by using Salpeter (S55) IMF with those by using Miller & Scalo (MS79) IMF, we find that the SFR.vs.L_Ha and SFR.vs.L_[OII] conversion factors by using S55 IMF are greater by 0.4 and 0.2 dex than those by using MS79 IMF for the models with and without BIs, respectively. The SFR.vs.L_{i,UV} and SFR.vs.L_FIR conversion factors by using S55 IMF are larger by an amount of 0.2 dex than the corresponding ones by using MS79 IMF. The inclusion of GRA only lowers these SFR calibrations at faint SFR. Moreover, comparing the results when using different EPS models, we find that the differences in the SFR.vs.L_Ha and SFR.vs.L_[OII] conversion factors reach ~ 0.7 and 0.9 dex, the difference in the SFR.vs.L_FIR conversion factor reaches 0.4 and 0.8 dex, and the differences in the SFR.vs.L_{i,UV} conversion factors reach 0.3 and 0.2 dex when using S55 and NON-S55 IMF (including Cha03, K01, K93' and MS79 IMFs, partly caused by the difference in the IMF), respectively. At last, we give the conversion coefficients between SFR and these diagnostics for all models.