Femtosecond X-ray absorption spectroscopy of pyrazine at the nitrogen K-edge: on the validity of the Lorentzian limit

We calculate the femtosecond X-ray absorption spectrum of pyrazine at the nitrogen K-edge including the wavepacket dynamics in both the valence and core-excited state manifolds. We do not invoke the widely used short-time (or Lorentzian) approximation which neglects the nuclear dynamics after the X-ray probe excitation. Instead, we calculate the X-ray-induced polarization in the time-domain where the optical pump as well as X-ray probe pulses are explicitly described. While the non-adiabatic population transfer following the optical excitation is well reproduced in the Lorentzian limit the transient X-ray absorption spectra obtained under this approximation lack some vibronic features, even when considering the short core-hole lifetime of nitrogen. We further demonstrate the effect of an increasingly longer pulse on the observed photo-triggered wavepacket dynamics which are blurred to the point that the X-ray probe response becomes effectively time-independent.

All together now: Simultaneous feature integration and feature retrieval in action control

Accounts of human action control assume integration of stimulus and response features at response execution and, upon repetition of some of those features, retrieval of other previously integrated features. Even though both processes contribute sequentially to observed binding effects in studies using a sequential prime-probe design, integration and retrieval processes theoretically affect human action simultaneously. That is, every action that we execute leads to bindings between features of stimuli and responses, while at the same time these features also trigger retrieval of other previously integrated features. Nevertheless, the paradigms used to measure binding effects in action control can only testify for integration of stimulus and response features at the first (R1, n-1, or prime) and retrieval of the past event via feature repetition at the second (R2, n, or probe) response. Here we combined two paradigms used in the action control literature to show that integration and retrieval do indeed function simultaneously. We found both significant stimulus-response and significant response-response binding effects, indicating that integration of responses must have occurred at the same time as response retrieval due to feature repetition and vice versa.

Synthesis of Catechol Derived Rosamine Dyes and Their Reactivity toward Biogenic Amines

Functional organic dyes play a key role in many fields, namely in biotechnology and medical diagnosis. Herein, we report two novel 2,3- and 3,4-dihydroxyphenyl substituted rosamines (3 and 4, respectively) that were successfully synthesized through a microwave-assisted protocol. The best reaction yields were obtained for rosamine 4, which also showed the most interesting photophysical properties, specially toward biogenic amines (BAs). Several amines including n- and t-butylamine, cadaverine, and putrescine cause spectral changes of 4, in UV–Vis and fluorescence spectra, which are indicative of their potential application as an effective tool to detect amines in acetonitrile solutions. In the gas phase, the probe response is more expressive for spermine and putrescine. Additionally, we found that methanolic solutions of rosamine 4 and n-butylamine undergo a pink to yellow color change over time, which has been attributed to the formation of a new compound. The latter was isolated and identified as 5 (9−aminopyronin), whose solutions exhibit a remarkable increase in fluorescence intensity together with a shift toward more energetic wavelengths. Other 9-aminopyronins 6a, 6b, 7a, and 7b were obtained from methanolic solutions of 4 with putrescine and cadaverine, demonstrating the potential of this new xanthene entity to react with primary amines.

Survey of the security risks of Wi-Fi networks based on the information elements of beacon and probe response frames

Wi-Fi networks have become prevalent in homes, businesses, and public places. Wi-Fi is one of the most common means that people use to access digital services like Facebook, WhatsApp, Instagram, email, and even payment platforms. Equipment for deploying Wi-Fi networks is affordable and its basic features are easy to manipulate. In many cases Wi-Fi users do not even have to buy any communication equipment, since Wi-Fi routers are installed by internet service providers (ISP) in the premises of their customers. Wi-Fi equipment, owned either by end users or ISP companies, should be configured as securely as possible to avoid potential attacks. The security capabilities and features of Wi-Fi routers and access points are inserted into beacon and probe response frames. Potential attackers can use sniffing tools like Wireshark to capture these frames and extract information about security features to discover vulnerabilities. In order to assess the security risks of Wi-Fi networks we conducted a survey in which we used Wireshark to capture the traffic from several Wi-Fi networks, and then through a filter we selected the beacon and probe response frames to analyze the security information elements carried by those frames. We came to the conclusion that despite technical recommendations, some security parameters and options are still set in a way that makes networks more prone to attacks. With this paper we want the readers to be aware of the security risks of their Wi-Fi networks, even the ones set up by their internet service providers.