Upgraded Cherenkov time-of-flight detector for the AFP project.

We present the results of our performance studies of the upgraded Cherenkov time-of-flight (ToF) detector for the AFP (ATLAS Forward Proton) project. The latest version consists of solid L-shaped fused silica bars, new customized ALD-coated micro-channel plate photomultipliers (MCP-PMTs) miniPlanacon XPM85112-S-R2D2 with an extended lifetime which operate at low gains (order of 103), and an updated construction. The improvements were aimed to increase the efficiency, the lifetime as well as the radiation hardness of the detector which has been designed to operate in high radiation areas (above 400 kGy/year). The detector was finally tested at the CERN-SPS test-beam facility (120 GeV π+ particles) in August 2021 prior to its installation at the Large Hadron Collider (LHC) at CERN. Measurements proved the detector kept its inner timing resolution of 20 ps despite the rather low gain of its photodetector and reduced optical throughput caused by inevitable changes in the detector geometry.

Highly economical and direct amination of sp3 carbon using low-cost nickel pincer catalyst.

Developing more efficient routes to achieve C-N bond coupling is of great importance to industries ranging from products in pharmaceuticals and fertilizers to biomedical technologies and next-generation electroactive materials. Over the past decade, improvements in catalyst design have moved synthesis away from expensive metals to newer inexpensive C-N cross-coupling approaches via direct amine alkylation. For the first time, we report the use of an amide-based nickel pincer catalyst (1) for direct alkylation of amines via activation of sp3 C-H bonds. The reaction was accomplished using a 0.2 mol% catalyst and no additional activating agents other than the base. Upon optimization, it was determined that the ideal reaction conditions involved solvent dimethyl sulfoxide at 110 °C for 3 h. The catalyst demonstrated excellent reactivity in the formation of various imines, intramolecularly cyclized amines, and substituted amines with a turnover number (TON) as high as 183. Depending on the base used for the reaction and the starting amines, the catalyst demonstrated high selectivity towards the product formation. The exploration into the mechanism and kinetics of the reaction pathway suggested the C-H activation as the rate-limiting step, with the reaction second-order overall, holding first-order behavior towards the catalyst and toluene substrate.

Performance studies of new optics for the time-of-flight detector of the AFP project.

We present the results of performance studies of the upgraded optical part of the time-of-flight subdetector prototype for the AFP (ATLAS Forward Proton) detector obtained during the test campaign in a synchrotron test-beam facility with 5 GeV electrons at the DESY laboratory (Hamburg, Germany) in June 2019. The detection of the particle arrival time is based on generation of Cherenkov light in an L-shaped fused silica bar. In the previous version of the ToF, all bars were made of two pieces (radiator and light guide) glued together with a dedicated glue (Epotek 305). This solution suffers from additional radiation damage of glue. We adopted a new technique of bar production without the need of glue. The new bars have a higher optical throughput by a factor of 1.6, reduced fragility, and better geometrical precision.

Polydopamine-Coated Manganese Complex/Graphene Nanocomposite for Enhanced Electrocatalytic Activity Towards Oxygen Reduction.

Platinum electrodes are commonly used electrocatalysts for oxygen reduction reactions (ORR) in fuel cells. However, this material is not economical due to its high cost and scarcity. We prepared an Mn(III) catalyst supported on graphene and further coated with polydopamine, resulting in superior ORR activity compared to the uncoated PDA structures. During ORR, a peak potential at 0.433 V was recorded, which is a significant shift compared to the uncoated material's -0.303 V (both versus SHE). All the materials reduced oxygen in a wide pH range via a four-electron pathway. Rotating disk electrode and rotating ring disk electrode studies of the polydopamine-coated material revealed ORR occurring via 4.14 and 4.00 electrons, respectively. A rate constant of 6.33 × 10(6) mol(-1)s(-1) was observed for the polydopamine-coated material-over 4.5 times greater than the uncoated nanocomposite and superior to those reported for similar carbon-supported metal catalysts. Simply integrating an inexpensive bioinspired polymer coating onto the Mn-graphene nanocomposite increased ORR performance significantly, with a peak potential shift of over +730 mV. This indicates that the material can reduce oxygen at a higher rate but with lower energy usage, revealing its excellent potential as an ORR electrocatalyst in fuel cells.

Simulating Personal Wealth in the Laboratory.

During laboratory gambling tasks participants are not typically allowed to wager their personal wealth. Instead, wealth is simulated by telling participants they have been endowed with game tokens that will be later exchanged for money. Past research indicates that participants undervalue game tokens following this procedure, which leads to elevated risk taking compared to procedures that add saliency or realism to the monetary payoff. A between-subjects experiment tested whether showing a picture of money during the endowment instructions and repeating token-money exchange information during the session influenced participants' preference for risky and riskless options. The results showed no effect of the money picture. However, repeated token-money exchange information significantly decreased risk taking. Together with past studies, this finding suggests that endowment procedures might establish greater value in game tokens, and therefore better simulate personal wealth, when the eventual exchange between game tokens and money is made more salient to participants.

Luminescence of La0.2Y1.8O3 nanostructured scintillators.

For the first time, transparent La0.2Y1.8O3 nanostructured polycrystalline scintillators were fabricated by sintering nanoparticle powders at high temperatures and their scintillation properties are reported. La0.2Y1.8O3 is a host material that has never been investigated as scintillators for radiation detection. Our observations found that La0.2Y1.8O3 has an intense scintillation luminescence, a detection efficiency higher than that of YAG:Ce and a comparable energy resolution to NaI and CsI scintillators. In addition, La0.2Y1.8O3 is stable and has luminescence decay lifetime in the picosecond range which is favorable for radiation detection. The luminescence of La0.2Y1.8O3 has a large Stokes-shift and a large emission bandwidth, and the luminescence is highly temperature dependent. Different from most doped scintillators, the luminescence of La0.2Y1.8O3 is most likely from the self-trapped excitons. The discovery of La0.2Y1.8O3 scintillators opens a new door for the research of new materials for radiation detection.

Contrast meals and malrotation in children-metal markers for improved accuracy.

Upper gastrointestinal contrast studies in children may cause false-positive or -negative diagnosis of intestinal malrotation from rotation of the patient. To alleviate this problem, skin markers can be used to reduce rotation of children undergoing this procedure, e.g., two metal markers (sheathed and sealed hypodermic needles) can be fixed onto the skin for gastro-intestinal contrast studies. We reviewed two Katz criteria influenced by patient rotation: duodenojejunal junction on or to the right of the left pedicle and pylorus to the left of the midline. A test group was positioned using markers; a control group without markers was positioned conventionally. Markers during a pilot study were applied, but positioning was done by helpers who had no on-screen visualization. In the test group, only 1 child (3%; n = 39) had a feature of malrotation. In the control group, there were features of malrotation in 12 children (25%; n = 48). No other features of malrotation were seen. The pilot study showed radiographic rotation with markers projecting off the midline in 78% of 58 children. This resulted in 48% of 58 patients having false features of malrotation. The use of metal skin markers results in reduction of rotational errors that could have caused false diagnosis of intestinal malrotation in children.

Laboratory simulated gambling: risk varies across participant-stake procedure.

This study investigated whether risk taking on a laboratory gambling task differed depending on whether participants gambled with earned or experimenter-provided game credits. Participants made repeated choices between two options, one to wager game credits on a game that produced probabilistic gains and losses, and one to gain game credits with certainty. Choice was investigated across stake and no-stake conditions and condition order was counterbalanced across conditions. Risk taking was higher under stake than no-stake conditions, but only when stake conditions were experienced first. There was no effect on risk taking of the amount of the certain gain. Results are consistent with previous research showing that participant-stake procedures promote greater risk taking than procedures that allow participants to gamble with their own earnings, and also show that experience gambling with earned credits has an enduring effect on risk taking.

Magnetic resonance imaging findings in spinal tuberculosis: Comparison of HIV positive and negative patients.

BACKGROUND: There is an increasing incidence of Human immunodeficiency virus (HIV) and tuberculosis (TB) co-infection. This has led to an increasing number of atypical features on magnetic resonance imaging (MRI). We postulated that the type 4 hypersensitivity response causing granulomatous inflammation may be disrupted by the HIV resulting in less vertebral body destruction. This study compares the MRI features of spinal tuberculosis in HIV positive and negative patients. MATERIALS AND METHODS: Fifty patients with confirmed spinal tuberculosis, HIV status and available MRI scans at a single institution from 2003-2009 were identified. HIV status was positive in 20 and negative in 30. Females were predominant (34:16). The HIV positive group was younger at 32.4 versus 46 years (P=0.008). Blood parameters (WCC, ESR, Hb, Lymphocyte count) were not significantly different between the HIV groups. MRI scans were reviewed by a radiologist who was blinded to the HIV status. Site, extent of disease, body collapse, abscess location and volume, kyphotic deformity and cord signal were reported. RESULTS: There was no difference between the number of vertebral bodies affection with TB involvement, presence of cord signal or incidence of non-contiguous lesions. The HIV negative group had significantly more total vertebral collapse (P=0.036) and greater kyphosis (P=0.002). The HIV positive group had a trend to larger anterior epidural pus collection (P=0.2). CONCLUSION: HIV negative patients demonstrate greater tuberculous destruction in terms of total percentage body collapse and resultant kyphosis. There is no difference in the incidence of cord signal or presence of non-contiguous lesions. HIV positive patients show a trend to a greater epidural abscess volume. This difference may be explained by the reduced autoimmune response of the type 4 hypersensitivity reaction caused by the HIV infection.

MRI findings in children with tuberculous meningitis: a comparison of HIV-infected and non-infected patients.

BACKGROUND: Radiological studies on HIV infection in tuberculous meningitis (TBM) in children are limited to small, retrospective studies using CT features. They report that HIV-infected children are less likely to display meningovascular enhancement, tuberculoma formation and obstructive hydrocephalus. No similar MRI-based studies were found in the literature. PURPOSE: The purpose of this study is to compare the MRI features of TBM in HIV-infected and uninfected children. METHODS: Retrospective descriptive study comparing clinical, laboratory and MRI features of 8 HIV-infected and 19 HIV-uninfected children with TBM. RESULTS: Intense basal meningeal enhancement occurred less frequently (p = 0.31) in HIV-infected children whilst cerebral atrophy was more commonly encountered (p = 0.06) Neither finding was however of statistical significance. All HIV-infected children had visible meningeal nodules on MR imaging compared to 72% in HIV-uninfected children with TBM. No differences were noted regarding number or location of infarcts and presence of hydrocephalus. Hydrocephalus in HIV-infected children was exclusively of communicating nature. CONCLUSIONS: The MRI criteria for diagnosis of TBM apply to HIV-infected children. The presence of nodular meningeal disease in all HIV-infected children has not previously been reported and requires further investigation.

Human responding on random-interval schedules of response-cost punishment: the role of reduced reinforcement density.

An experiment with adult humans investigated the effects of response-contingent money loss (response-cost punishment) on monetary-reinforced responding. A yoked-control procedure was used to separate the effects on responding of the response-cost contingency from the effects of reduced reinforcement density. Eight adults pressed buttons for money on a three-component multiple reinforcement schedule. During baseline, responding in all components produced money gains according to a random-interval 20-s schedule. During punishment conditions, responding during the punishment component conjointly produced money losses according to a random-interval schedule. The value of the response-cost schedule was manipulated across conditions to systematically evaluate the effects on responding of response-cost frequency. Participants were assigned to one of two yoked-control conditions. For participants in the Yoked Punishment group, during punishment conditions money losses were delivered in the yoked component response independently at the same intervals that money losses were produced in the punishment component. For participants in the Yoked Reinforcement group, responding in the yoked component produced the same net earnings as produced in the punishment component. In 6 of 8 participants, contingent response cost selectively decreased response rates in the punishment component and the magnitude of the decrease was directly related to the punishment schedule value. Under punishment conditions, for participants in the Yoked Punishment group response rates in the yoked component also decreased, but the decrease was less than that observed in the punishment component, whereas for participants in the Yoked Reinforcement group response rates in the yoked component remained similar to rates in the no-punishment component. These results provide further evidence that contingent response cost functions similarly to noxious punishers in that it appears to suppress responding apart from its effects on reinforcement density.

Effects of monetary reserves and rate of gain on human risky choice under budget constraints.

The energy-budget rule is an optimal foraging model that predicts that choice should be risk averse when net gains plus reserves meet energy requirements (positive energy-budget conditions) and risk prone when net gains plus reserves fall below requirements (negative energy-budget conditions). Studies have shown that the energy-budget rule provides a good description of risky choice in humans when choice is studied under economic conditions (i.e., earnings budgets) that simulate positive and negative energy budgets. In previous human studies, earnings budgets were manipulated by varying earnings requirements, but in most nonhuman studies, energy budgets have been manipulated by varying reserves and/or mean rates of reinforcement. The present study therefore investigated choice in humans between certain and variable monetary outcomes when earnings budgets were manipulated by varying monetary reserves and mean rates of monetary gain. Consistent with the energy-budget rule, choice tended to be risk averse under positive-budget conditions and risk neutral or risk prone under negative-budget conditions. Sequential choices were also well described by a dynamic optimization model, especially when expected earnings for optimal choices were high. These results replicate and extend the results of prior experiments in showing that humans' choices are generally consistent with the predictions of the energy-budget rule when studied under conditions analogous to those used in nonhuman energy-budget studies, and that choice patterns tend to maximize reinforcement.

Accuracy of radiographer reporting of paediatric brain CT.

BACKGROUND: Radiographer reporting has been studied for plain films and for ultrasonography, but not in paediatric brain CT in the emergency setting. OBJECTIVE: To study the accuracy of radiographer reporting in paediatric brain CT. MATERIALS AND METHODS: We prospectively collected 100 paediatric brain CT examinations. Films were read from hard copies using a prescribed tick sheet. Radiographers with 12 years' and 3 years' experience, respectively, were blinded to the history and were not trained in diagnostic film interpretation. The radiographers' results were compared with those of a consultant radiologist. Three categories were defined: abnormal scans, significant abnormalities and insignificant abnormalities. RESULTS: Both radiographers had an accuracy of 89.5% in reading a scan correctly as abnormal, and radiographer 1 had a sensitivity of 87.8% and radiographer 2 a sensitivity of 96%. Radiographer 1 had an accuracy in detecting a significant abnormality of 75% and radiographer 2 an accuracy of 48.6%, and the sensitivities for this category were 61.6% and 52.9%, respectively. Results for detecting the insignificant abnormalities were poorer. CONCLUSIONS: Selected radiographers could play an effective screening role, but lacking the sensitivity required for detecting significant abnormality, they could not be the final diagnostician. We recommend that the study be repeated after both radiographers have received formal training in interpretation of paediatric brain CT.

Discriminative stimulus effects of gamma-hydroxybutyrate (GHB) and its metabolic precursor, gamma-butyrolactone (GBL) in rats.

RATIONALE: Gamma-hydroxybutyrate (GHB) is becoming an increasingly popular drug of abuse. Metabolic precursors of GHB, gamma-butyrolactone (GBL) and 1,4-butanediol (BDL), are commercially available industrial solvents that may also present potential health risks. Relatively little is known about the neurobehavioral effects of GHB and its precursors. OBJECTIVE: The aim of the present investigation was to characterize the discriminative stimulus effects of GHB and its precursor, GBL. METHODS: Male Sprague-Dawley rats were trained to discriminate GHB [300 mg/kg, i.g.; n=16] or GBL (150 mg/kg, i.p.; n=8) from vehicle under a fixed ratio 20 (FR 20) schedule of food reinforcement. Stimulus generalization tests were then conducted with several compounds. RESULTS: GHB and GBL produced cross-generalization and BDL was fully substituted for both GHB and GBL. Two benzodiazepines, alprazolam and diazepam, and the 5-HT1A agonist, buspirone, did not substitute for either training drug nor did ethanol or the NMDA antagonists, PCP and ketamine. The GHB antagonist, NCS-382, and the GABA(B) antagonist, CGP-35348, blocked the discriminative stimulus effects of GHB but not those of GBL. CONCLUSIONS: These findings suggest that GHB and its metabolic precursors produce similar subjective effects that differ from those of other sedative-hypnotic drugs. Further investigations into the neurochemical actions underlying the subjective effects of these drugs are warranted.

Up or down: the influence of upcoming reinforcement on consummatory and operant behavior.

Research has shown that animal subjects that are given a chance to consume a low-valued substance will consume less of it if a high-valued substance will soon be available than they would if the low-valued substance were to remain available (negative consummatory contrast). Research has also shown that subjects that lever press for a low-valued reinforcer will press the lever more often for that reinforcer if they will soon be able to lever press for a high-valued reinforcer than they would if they continue to press for the low-valued reinforcer (positive induction). The present study investigated these different changes in behavior across 3 experiments. The results suggest that the occurrence of contrast or induction does not depend on the type of substances that are used. We argue that further investigation of the contrast vs. induction issue is warranted because it has empirical, theoretical, and applied implications.