Extraction of ∣Vcd∣|V_{cd}| and ∣Vcs∣|V_{cs}| from experimental decay rates using lattice QCD D→π(K)ℓνD \to \pi(K) \ell \nu form factors

We present a determination of the Cabibbo-Kobayashi-Maskawa matrix elements $|V_{cd}|$ and $|V_{cs}|$ obtained by combining the momentum dependence of the semileptonic vector form factors $f_+^{D \to \pi}(q^2)$ and $f_+^{D \to K}(q^2)$, recently determined from lattice QCD simulations, with the differential rates measured for the semileptonic $D \to \pi \ell \nu$ and $D \to K \ell \nu$ decays. Our analysis is based on the results for the semileptonic form factors produced by the European Twisted Mass Collaboration with $N_f = 2 + 1 + 1$ flavors of dynamical quarks in the whole range of values of the squared 4-momentum transfer accessible in the experiments. The statistical and systematic correlations between the lattice data as well as those present in the experimental data are properly taken into account. With respect to the standard procedure based on the use of only the vector form factor at zero 4-momentum transfer, we obtain more precise and consistent results: $|V_{cd} |= 0.2341 ~ (74)$ and $|V_{cs} |= 0.970 ~ (33)$. The second-row CKM unitarity is fulfilled within the current uncertainties: $|V_{cd}|^2 + |V_{cs}|^2 + |V_{cb}|^2 = 0.996 ~ (64)$. Moreover, using for the first time hadronic inputs determined from first principles, we have calculated the ratio of the semileptonic $D \to \pi(K)$ decay rates into muons and electrons, which represent a test of lepton universality within the SM, obtaining in the isospin-symmetric limit of QCD: ${\cal{R}}_{LU}^{D\pi} = 0.985~(2)$ and ${\cal{R}}_{LU}^{DK} = 0.975~(1)$.Comment: 8 pages, 2 figures, 8 tables. Version to appear in EPJ

Hypercubic effects in semileptonic decays of heavy mesons, toward B→πℓνB \to \pi \ell \nu, with Nf=2+1+1N_f=2+1+1 Twisted fermions

We present a preliminary study toward a lattice determination of the vector and scalar form factors of the $B \to \pi \ell \nu$ semileptonic decays. We compute the form factors relative to the transition between heavy-light pseudoscalar mesons, with masses above the physical D-mass, and the pion. We simulate heavy-quark masses in the range $m_c^{phys} < m_h < 2m_c^{phys}$. Lorentz symmetry breaking due to hypercubic effects is clearly observed in the data, and included in the decomposition of the current matrix elements in terms of additional form factors. We discuss the size of this breaking as the parent-meson mass increases. Our analysis is based on the gauge configurations produced by the European Twisted Mass Collaboration with $N_f = 2 + 1 + 1$ flavors of dynamical quarks at three different values of the lattice spacing and with pion masses as small as $210$ MeV.Comment: 7 pages, 5 figures; contribution to the XXXVI International Symposium on Lattice Field Theory (LATTICE2018), East Lansing (Michigan State University, USA), July 22-28, 201

Spin up and phase fluctuations in the timing of the accreting millisecond pulsar XTE J1807-294

We performed a timing analysis of the 2003 outburst of the accreting X-ray millisecond pulsar XTE J1807-294 observed by RXTE. Using recently refined orbital parameters we report for the first time a precise estimate of the spin frequency and of the spin frequency derivative. The phase delays of the pulse profile show a strong erratic behavior superposed to what appears as a global spin-up trend. The erratic behavior of the pulse phases is strongly related to rapid variations of the light curve, making it very difficult to fit these phase delays with a simple law. As in previous cases, we have therefore analyzed separately the phase delays of the first harmonic and of the second harmonic of the spin frequency, finding that the phases of the second harmonic are far less affected by the erratic behavior. In the hypothesis that the second harmonic pulse phase delays are a good tracer of the spin frequency evolution we give for the first time a estimation of the spin frequency derivative in this source. The source shows a clear spin-up of $\dot \nu = 2.5(7) \times 10^{-14}$ Hz sec$^{-1}$ (1 $\sigma$ confidence level). The largest source of uncertainty in the value of the spin-up rate is given by the uncertainties on the source position in the sky. We discuss this systematics on the spin frequency and its derivative.Comment: 17 pages, 4 figures, Accepted by Ap

The Small-er Screen: YouTube Vlogging and the Unequipped Child Entertainment Labor Laws

Family vloggers are among the millions of content creators on YouTube. In general, vloggers frequently upload recorded videos of their daily lives. Family vloggers are unique because they focus their content around their familial relationships and the lives of their children. One set of family vloggers, the Ace Family, has recorded their children’s lives from the day they were born and continue to upload videos of each milestone, including “Elle Cries on Her First Rollercoaster Ride” and “Elle and Alaïa Get Caught Doing What!! **Hidden Camera**.” Another vlogging couple, Cole and Savannah LaBrant, post similar content, including videos titled “Baby Posie’s Health Emergency” and “Everleigh Doesn’t Want a Baby Sister.” Family channels often involve pranks and reactions, most of which are centered around young children. Given their high amounts of views and subscribers, channels like these are monetized by YouTube and granted various brand sponsorships. What looks like studio-quality home videos have actually become part of a booming business, and child labor laws have failed to protect children who have essentially become employees of the Internet. Children on YouTube and social media are not treated the same way as, for example, child actors on a movie set are. Parents are free to involve their children in content in whatever way they desire—as long as they do not violate YouTube community guidelines—without worrying about time regulations, filming conditions, licensing requirements, or setting up funds for their children’s work. The general concern about children’s safety on the Internet has been especially relevant since the growth of the platform TikTok. Potentially “more than a third of [TikTok’s] 49 million daily users . . . in the United States [are] 14 years old or younger.” In fact, TikTok’s most followed creator, Charli D’Amelio, is a minor. Although the concern for the safety of younger users on TikTok may be different than the concern for children on YouTube given parental involvement in YouTube content creation, the rapid growth and accessibility of TikTok is an example of the ever-growing and evolving social media culture in the United States and around the world. TikTok utilizes a recommendation style algorithm known as the “For You” page that personalizes a feed of videos for its users. Although the exact algorithm may be somewhat of a mystery, it suggests that the platform itself has some control over which videos users are exposed to based on that user’s activity. TikTok has also become another social media platform where users can monetize their content and include brand sponsorships similar to those found on YouTube and Instagram. In 2020, TikTok began planning a $200 million fund to support its creators. Unlike many YouTube videos, “TikToks” are a minute or less in duration, making them much more user-friendly for beginners and easier to make and upload. As such, parents uploading videos of their children is also common practice on TikTok, just as it is on YouTube or Instagram. Some parents have even created accounts that consist almost entirely of videos of their babies. Although TikTok’s history as a platform is much shorter than YouTube’s, it serves as a good example of the direction social media is heading toward: content that is becoming easier to upload and watch. User-generated content on various social media platforms such as YouTube, Instagram, and TikTok is now a prevalent form of modern entertainment, and it involves child participants much like the use of child actors in television and film. Child labor laws fail to keep pace with the rapidly evolving Internet entertainment ecosystem, and this issue requires specific action by the legislature and corporations behind popular social media platforms. This Comment covers child entertainment labor laws in the United States and some of the legislative history behind child labor laws to demonstrate the need for expanded and newly adopted legislation to accommodate the new world of user-generated content. It discusses the nature of family vlogging and how it compares to traditional entertainment media and argues for a multitude of legislative changes to better protect children’s interests when they are featured in social media posts for monetary gain, including: the application of federal child labor laws to family vlogging and social media influencing, the adoption of child entertainment labor laws in individual states, an expansion of the pre-existing provisions to include entertainment on social media platforms, and the adaptation of YouTube community guidelines to better safeguard the interests of children who appear on family vlog channels

Is porto sinusoidal vascular disease to be actively searched in patients with portal vein thrombosis?

Porto sinusoidal vascular liver disease (PSVD) and portal vein thrombosis (PVT) are distinct vascular liver diseases characterized, respectively, by an intrahepatic and a prehepatic obstacle to the flow in the liver portal system. PVT may also occur as a complication of the natural history of PSVD, especially if a prothrombotic condition coexists. In other cases, it is associated to local and systemic pro-thrombotic conditions, even if its cause remains unknown in up to 25% despite an active search. In our opinion, the presence of PSVD should be suspected in patients with PVT especially in those with PVT "sine causa" and the active search of this condition should be included in their diagnostic work-out. However, sometimes the diagnosis of pre-existing PSVD is very hard. Biopsy cannot be fully discriminant as similar histological data have been described in both conditions. Liver stiffness may help as it has been shown to be higher in PSVD than in "pure" PVT, due to the presence of sclerosis in the portal venous radicles observable in PSVD patients. Nevertheless, comparing liver stiffness between PVT and PSVD has until now been restricted to very limited series of patients. In conclusion, even if it is still totally hypothetical, our point of view may have clinical consequences, especially when deciding to perform a liver biopsy in patients with a higher liver stiffness and suspending the anticoagulation in patients with PVT and no detectable prothrombotic factors

Timing of the Accreting Millisecond Pulsar XTE J1814-338

We present a precise timing analysis of the accreting millisecond pulsar XTE J1814-338 during its 2003 outburst, observed by RXTE. A full orbital solution is given for the first time; Doppler effects induced by the motion of the source in the binary system were corrected, leading to a refined estimate of the orbital period, P_orb=15388.7229(2)s, and of the projected semimajor axis, a sini/c= 390.633(9) lt-ms. We could then investigate the spin behaviour of the accreting compact object during the outburst. We report here a refined value of the spin frequency (nu=314.35610879(1) Hz) and the first estimate of the spin frequency derivative of this source while accreting (nu^dot=(-6.7 +/- 0.7) 10^(-14) Hz/s). This spin down behaviour arises when both the fundamental frequency and the second harmonic are taken into consideration. We discuss this in the context of the interaction between the disc and the quickly rotating magnetosphere, at accretion rates sufficiently low to allow a threading of the accretion disc in regions where the Keplerian velocity is slower than the magnetosphere velocity. We also present indications of a jitter of the pulse phases around the mean trend, which we argue results from movements of the accreting hotspots in response to variations of the accretion rate.Comment: 7 pages, 4 figures, Accepted for publication by MNRA

Protein adsorption onto Fe3O4 nanoparticles with opposite surface charge and its impact on cell uptake

Nanoparticles (NPs) engineered for biomedical applications are meant to be in contact with protein-rich physiological fluids. These proteins are usually adsorbed onto the NP surface, forming a swaddling layer called protein corona that influences cell internalization. We present a study on protein adsorption onto different magnetic NPs (MNPs) when immersed in cell culture medium, and how these changes affect the cellular uptake. Two colloids with magnetite cores of 25 nm, same hydrodynamic size and opposite surface charge were in situ coated with (a) positive polyethyleneimine (PEI-MNPs) and (b) negative poly(acrylic acid) (PAA-MNPs). After few minutes of incubation in cell culture medium the wrapping of the MNPs by protein adsorption resulted in a 5-fold size increase. After 24 h of incubation large MNP-protein aggregates with hydrodynamic sizes 1500 to 3000 nm (PAA-MNPs and PEI-MNPs respectively) were observed. Each cluster contained an estimated number of magnetic cores between 450 and 1000, indicating the formation of large aggregates with a "plum pudding" structure of MNPs embedded into a protein network of negative surface charge irrespective of the MNP_core charge. We demonstrated that PEI-MNPs are incorporated in much larger amounts than the PAA-MNPs units. Quantitative analysis showed that SH-SY5Y cells can incorporate 100 per cent of the added PEI-MNPs up to about 100 pg per cell, whereas for PAA-MNPs the uptake was less than 50 percent. The final cellular distribution showed also notable differences regarding partial attachment to the cell membrane. These results highlight the need to characterize the final properties of MNPs after protein adsorption in biological media, and demonstrate the impact of these properties on the internalization mechanisms in neural cells.Comment: 32 pages, 10 figure

Handle-hand compatibility effects for the right and left hand using reach-to-touch movements

In stimulus-response compatibility tasks, performance is better when the handle of an object is oriented on the same side of the response than when the handle is oriented on the opposite side. Two major alternative accounts, the motor affordance and spatial accounts, have been proposed to explain this handle-hand compatibility effect. In two experiments, we tested between these two accounts by administering a go/no-go task to right-handed participants. Handled objects presented on a touchscreen were used as stimuli. Half of the participants had to reach-to-touch the stimuli by using their dominant hand, the other half by using their nondominant hand. Liftoff times (LTs), movement times (MTs) and spatial coordinates of the movement endpoints were recorded. Results from the LTs and MTs analyses showed no evidence of handle-hand compatibility effects. In contrast, the analyses of the spatial coordinates revealed that participants' touches were shifted more laterally towards the handle when the handles were oriented on the same side of the responding hand (Experiments 1 and 2). Furthermore, the right-hand touches landed higher (towards the handle) than the left-hand touches, especially when the vertical object dimension was particularly salient (Experiment 1). Overall, these results are in line with the activation of hand motor programs to reach and grasp the object as predicted by the motor account, at least for the right/dominant hand