Concepts in the Classroom, Programming in the Lab

Computing Curricula 1991 calls for breadth in the undergraduate computer science curriculum. Many authors have recommended structured laboratories for computer science. This is a report on a project to combine these goals in an introductory sequence of courses. We present two courses in which all programming is done in a laboratory environment, leaving the lectures for more conceptual material that ranges over a broad selection of topics. Student reactions to this project have been very positive – we have increased the number of students continuing with the major, as well as student satisfaction with the courses themselves

Classifying the activity states of small vertebrates using automated VHF telemetry

Abstract The most basic behavioural states of animals can be described as active or passive. While high‐resolution observations of activity patterns can provide insights into the ecology of animal species, few methods are able to measure the activity of individuals of small taxa in their natural environment. We present a novel approach in which a combination of automatic radiotracking and machine learning is used to distinguish between active and passive behaviour in small vertebrates fitted with lightweight transmitters (3 million signals from very‐high‐frequency (VHF) telemetry from two forest‐dwelling bat species (Myotis bechsteinii [n = 52] and Nyctalus leisleri [n = 20]) to train and test a random forest model in assigning either active or passive behaviour to VHF‐tagged individuals. The generalisability of the model was demonstrated by recording and classifying the behaviour of tagged birds and by simulating the effect of different activity levels with the help of humans carrying transmitters. The model successfully classified the activity states of bats as well as those of birds and humans, although the latter were not included in model training (F1 0.96–0.98). We provide an ecological case‐study demonstrating the potential of this automated monitoring tool. We used the trained models to compare differences in the daily activity patterns of two bat species. The analysis showed a pronounced bimodal activity distribution of N. leisleri over the course of the night while the night‐time activity of M. bechsteinii was relatively constant. These results show that subtle differences in the timing of species' activity can be distinguished using our method. Our approach can classify VHF‐signal patterns into fundamental behavioural states with high precision and is applicable to different terrestrial and flying vertebrates. To encourage the broader use of our radiotracking method, we provide the trained random forest models together with an R package that includes all necessary data processing functionalities. In combination with state‐of‐the‐art open‐source automated radiotracking, this toolset can be used by the scientific community to investigate the activity patterns of small vertebrates with high temporal resolution, even in dense vegetation

Classifying the activity states of small vertebrates using automated VHF telemetry

The most basic behavioural states of animals can be described as active or passive. However, while high-resolution observations of activity patterns can provide insights into the ecology of animal species, few methods are able to measure the activity of individuals of small taxa in their natural environment. We present a novel approach in which the automated VHF radio-tracking of small vertebrates fitted with lightweight transmitters (< 0.2 g) is used to distinguish between active and passive behavioural states. A dataset containing > 3 million VHF signals was used to train and test a random forest model in the assignment of either active or passive behaviour to individuals from two forest-dwelling bat species (Myotis bechsteinii (n = 50) and Nyctalus leisleri (n = 20)). The applicability of the model to other taxonomic groups was demonstrated by recording and classifying the behaviour of a tagged bird and by simulating the effect of different types of vertebrate activity with the help of humans carrying transmitters. The random forest model successfully classified the activity states of bats as well as those of birds and humans, although the latter were not included in model training (F-score 0.96–0.98). The utility of the model in tackling ecologically relevant questions was demonstrated in a study of the differences in the daily activity patterns of the two bat species. The analysis showed a pronounced bimodal activity distribution of N. leisleri over the course of the night while the night-time activity of M. bechsteinii was relatively constant. These results show that significant differences in the timing of species activity according to ecological preferences or seasonality can be distinguished using our method. Our approach enables the assignment of VHF signal patterns to fundamental behavioural states with high precision and is applicable to different terrestrial and flying vertebrates. To encourage the broader use of our radio-tracking method, we provide the trained random forest models together with an R-package that includes all necessary data-processing functionalities. In combination with state-of-the-art open-source automated radio-tracking, this toolset can be used by the scientific community to investigate the activity patterns of small vertebrates with high temporal resolution, even in dense vegetation

Diffractive hard photoproduction at HERA and evidence for the gluon content of the pomeron

Inclusive jet cross sections for events with a large rapidity gap with respect to the proton direction from the reaction ep → jet + X with quasi-real photons have been measured with the ZEUS detector. The cross sections refer to jets with transverse energies E T jet > 8 GeV. The data show the characteristics of a diffractive process mediated by pomeron exchange. Assuming that the events are due to the exchange of a pomeron with partonic structure, the quark and gluon content of the pomeron is probed at a scale ∼ ( E T jet ) 2 . A comparison of the measurements with model predictions based on QCD plus Regge phenomenology requires a contribution of partons with a hard momentum density in the pomeron. A combined analysis of the jet cross sections and recent ZEUS measurements of the diffractive structure function in deep inelastic scattering gives the first experimental evidence for the gluon content of the pomeron in diffractive hard scattering processes. The data indicate that between 30% and 80% of the momentum of the pomeron carried by partons is due to hard gluons

Neutral strange particle production in deep inelastic scattering at HERA

This paper presents measurements of \k\ and \lam\ production in neutral current, deep inelastic scattering of 26.7 GeV electrons and 820 GeV protons in the kinematic range $10 0.04$. Average multiplicities for \k\ and \lam\ production are determined for transverse momenta \ \ptr\ $> 0.5$ GeV and pseudorapidities $\left| \eta \right| < 1.3$. The multiplicities favour a stronger strange to light quark suppression in the fragmentation chain than found in $e~+ e~-$ experiments. The production properties of \k's in events with and without a large rapidity gap with respect to the proton direction are compared. The ratio of neutral \k's to charged particles per event in the measured kinematic range is, within the present statistics, the same in both samples

Study of the photon remnant in resolved photoproduction at HERA

Photoproduction at HERA is studied in ep collisions, with the ZEUS detector, for γp centre-of-mass energies ranging from 130–270 GeV. A sample of events with two high- p T jets ( p T > 6 GeV, η < 1.6) and a third cluster in the approximate direction of the electron beam is isolated using a clustering algorithm. These events are mostly due to resolved photoproduction. The third cluster is identified as the photon remnant. Its properties, such as the transverse and longitudinal energy flows around the axis of the cluster, are consistent with those commonly attributed to jets, and in particular with those found for the two jets in these events. The mean value of the photon remnant p T with respect to the beam axis is measured to be 2.1 ± 0.2 GeV, which demonstrates substantial mean transverse momenta for the photon remnant

Extraction of the gluon density of the proton at small xx

The gluon momentum density $x_g ( x , Q^2 )$ of the proton was extracted at $Q^2 = 20$ GeV$^2$ for small values of $x$ between $4 \times 10^{−4}$ and $10^{−2}$ from the scaling violations of the proton structure function $F_2$ measured recently by ZEUS in deep inelastic neutral current ep scattering at HERA. The extraction was performed in two ways. Firstly, using a global NLO fit to the ZEUS data on $F_2$ at low $x$ constrained by measurements from NMC at larger $x$; and secondly using published approximate methods for the solution of the GLAP QCD evolution equations. Consistent results are obtained. A substantial increase of the gluon density is found at small $x$ in comparison with the NMC result obtained at larger values of $x$

Measurement of the cross-section for the reaction gamme-P-]J/PSI-P with the ZEUS detector at HERA

This paper reports the cross section measurements for the process ep --> e J/psi p for Q(2) < 4 GeV2 at root s = 296 GeV, based on an integrated luminosity of about 0.5 pb(-1), using the ZEUS detector. The J/psi was detected in its e(+)e(-) and mu(+)mu(-) decay modes. The photoproduction cross section was measured to be 52(-12)(+7) +/- 10 nb at an average gamma p centre of mass energy of 67 GeV and 71(-20)(+13) +/- 12 nb at 114 GeV. The significant rise of the cross section compared to lower energy measurements is not in agreement with VDM models, but can be described by QCD inspired models if a rise in the gluon momentum density at low x in the proton is assumed

Measurement of the diffractive structure function in deep elastic scattering at HERA

This paper presents an analysis of the inclusive properties of diffractive deep inelastic scattering events produced in $ep$ interactions at HERA. The events are characterised by a rapidity gap between the outgoing proton system and the remaining hadronic system. Inclusive distributions are presented and compared with Monte Carlo models for diffractive processes. The data are consistent with models where the pomeron structure function has a hard and a soft contribution. The diffractive structure function is measured as a function of $x_{\mathbb p}$, the momentum fraction lost by the proton, of $\beta$, the momentum fraction of the struck quark with respect to $x_{\mathbb p}$, and of $Q^2$. The $x_{\mathbb p}$ dependence is consistent with the form$(1/x_{\mathbb p})^a$ where $a=1.30\pm0.08(stat)~{+0.08}_{-0.14}(sys)$ in all bins of $\beta$ and $Q^2$. In the measured $Q^2$ range, the diffractive structure function approximately scales with $Q^2$ at fixed $\beta$. In an Ingelman-Schlein type model, where commonly used pomeron flux factor normalisations are assumed, it is found that the quarks within the pomeron do not saturate the momentum sum rule