Large-scale algorithmic search identifies stiff and sloppy dimensions in synaptic architectures consistent with murine neocortical wiring

Complex systems can be defined by "sloppy" dimensions, meaning that their behavior is unmodified by large changes to specific parameter combinations, and "stiff" dimensions whose changes result in considerable modifications. In the case of the neocortex, sloppiness in synaptic architectures would be crucial to allow for the maintenance of spiking dynamics in the normal range despite a diversity of inputs and both short- and long-term changes to connectivity. Using simulations on neural networks with spiking matched to murine visual cortex, we determined the stiff and sloppy parameters of synaptic architectures across three classes of input (brief, continuous, and cyclical). Large-scale algorithmically-generated connectivity parameter values revealed that specific combinations of excitatory and inhibitory connectivity are stiff and that all other architectural details are sloppy. Stiff dimensions are consistent across a range of different input classes with self-sustaining synaptic architectures occupying a smaller subspace as compared to the other input classes. We also find that experimentally estimated connectivity probabilities from mouse visual cortex are similarly stiff and sloppy when compared to the architectures that we identified algorithmically. This suggests that simple statistical descriptions of spiking dynamics are a sufficient and parsimonious description of neocortical activity when examining structure-function relationships at the mesoscopic scale. Moreover, this study provides further evidence of the importance of the interrelationship of excitatory and inhibitory connectivity to establish and maintain stable spiking dynamical regimes in neocortex.

Feedback Loops: Algorithmic Authority, Emergent Biases, and Implications for Information Literacy

Algorithms have become increasingly ubiquitous in our modern, technologically driven society. Algorithmic tools that are embedded to “enhance” the user experience when information-seeking carry problematic epistemological concerns. These algorithms are developed and interjected into search tools by human beings who, consciously or not, tend to impart biases into the functionality of the information retrieval process. These search tools have become our primary arbiters of knowledge and have been granted relatively unmitigated sovereignty over our perceptions of reality and truth. This article provides broader awareness of how the bias embedded within these algorithmic systems structures users’ perception and knowledge of the world, preserving traditional power hierarchies and the marginalization of specific groups of people, and examines the implications of algorithmic search systems on information literacy instruction from a critical pedagogical perspective.

Digital chemsex publics: Algorithmic and user configurations of fear and desire on Pornhub

In recent years, chemsex has emerged as both a subcultural vernacular and an orientation device for gay health promotion. Chemsex loosely describes gay men using certain drugs to extend and modulate group sex practice. In line with hegemonic responses to gay sexuality in general, most research has been grounded in problematisation, with discourse mostly returning to the question of containment. Drawing on porn, platform and critical drug studies, this article offers a corrective approach by defining a networked, cultural study of chemsex that is attuned to how chemsex erotics operate in many different (digital) intimate publics. Assembling algorithmic search suggestions, 41 videos and 450 comments, the article finds that the videos and comments found through the search function are vastly different than those found through user-generated playlists. Two competing publics form around the fear/desire-response to drug use: a cautious erotic of disinhibition and a counterpublic erotic of transgression.

Fear and desire in chemsex publics on Pornhub

In recent years, chemsex has emerged as both a subcultural vernacular and an orientation device for gay health promotion. Chemsex loosely describes gay men using certain drugs to extend and modulate group sex practice. In line with hegemonic responses to gay sexuality in general, most research has been grounded in problematisation, with discourse mostly returning to the question of containment. Drawing on porn, platform and critical drug studies, the study offers a corrective approach, this article defines a networked, cultural study of chemsex that is attuned to how chemsex erotics operate in many different (digital) intimate publics. Assembling algorithmic search suggestions, 41 videos and 450 comments, the article finds that the videos and comments found through the search function are vastly different than those found through user-generated playlists. Two competing publics form around the fear/desire-response to drug use: a cautious erotic of disinhibition, and a counterpublic erotic of transgression.

A method of constructing maximin distance designs

One attractive class of space-filling designs for computer experiments is that of maximin distance designs. Algorithmic search for such designs is commonly used but this method becomes ineffective for large problems. Theoretical construction of maximin distance designs is challenging; some results have been obtained recently, often by employing highly specialized techniques. This paper presents an easy-to-use method for constructing maximin distance designs. The method is versatile as it is applicable for any distance measure. Our basic idea is to construct large designs from small designs and the method is effective because the quality of large designs is guaranteed by that of small designs, as evaluated by the maximin distance criterion.

Quasi-stellar objects acting as potential strong gravitational lenses in the SDSS-III BOSS survey

We present a sample of 12 quasi-stellar objects (QSOs) that potentially act as strong gravitational lenses on background emission line galaxies (ELG) or Lyman-α emitters (LAEs) selected through a systematic search of the 297 301 QSOs in the Sloan Digital Sky Survey (SDSS)-III Data Release 12. Candidates were identified by looking for compound spectra, where emission lines at a redshift larger than that of the quasar can be identified in the residuals after a QSO spectral template is subtracted from the observed spectra. The narrow diameter of BOSS fibers (2″) then ensures that the object responsible for the additional emission lines must lie close to the line of sight of the QSO and hence provides a high probability of lensing. Among the 12 candidates identified, nine have definite evidence for the presence of a background ELG identified by at least four higher-redshift nebular emission lines. The remaining three probable candidates present a strong asymmetrical emission line attributed to a background Lyman-α emitter (LAE). The QSO-ELG (QSO-LAE) lens candidates have QSO lens redshifts in the range 0.24 ≲ zQSO ≲ 0.66 (0.75 ≲ zQSO ≲ 1.23 ) and background galaxy redshifts in the range 0.48 ≲ zS, ELG ≲ 0.94 (2.17 ≲ zS, LAE ≲ 4.48). We show that the algorithmic search is complete at > 90% for QSO-ELG systems, whereas it falls at 40−60% for QSO-LAE, depending on the redshift of the source. Upon confirmation of the lensing nature of the systems, this sample may quadruple the number of known QSOs acting as strong lenses. We have determined the completeness of our search, which allows future studies to compute lensing probabilities of galaxies by QSOs and differentiate between different QSO models. Future imaging of the full sample and lens modelling offers a unique approach to study and constrain key properties of QSOs.