Observation of high-energy neutrinos from the Galactic plane

The origin of high-energy cosmic rays, atomic nuclei that continuously impact Earth's atmosphere, is unknown. Because of deflection by interstellar magnetic fields, cosmic rays produced within the Milky Way arrive at Earth from random directions. However, cosmic rays interact with matter near their sources and during propagation, which produces high-energy neutrinos. We searched for neutrino emission using machine learning techniques applied to 10 years of data from the IceCube Neutrino Observatory. By comparing diffuse emission models to a background-only hypothesis, we identified neutrino emission from the Galactic plane at the 4.5σ level of significance. The signal is consistent with diffuse emission of neutrinos from the Milky Way but could also arise from a population of unresolved point sources.

Evidence for neutrino emission from the nearby active galaxy NGC 1068

A supermassive black hole, obscured by cosmic dust, powers the nearby active galaxy NGC 1068. Neutrinos, which rarely interact with matter, could provide information on the galaxy’s active core. We searched for neutrino emission from astrophysical objects using data recorded with the IceCube neutrino detector between 2011 and 2020. The positions of 110 known gamma-ray sources were individually searched for neutrino detections above atmospheric and cosmic backgrounds. We found that NGC 1068 has an excess of 79 − 20 + 22 neutrinos at tera–electron volt energies, with a global significance of 4.2σ, which we interpret as associated with the active galaxy. The flux of high-energy neutrinos that we measured from NGC 1068 is more than an order of magnitude higher than the upper limit on emissions of tera–electron volt gamma rays from this source.

Search for Unstable Sterile Neutrinos with the IceCube Neutrino Observatory

We present a search for an unstable sterile neutrino by looking for a resonant signal in eight years of atmospheric ν_{μ} data collected from 2011 to 2019 at the IceCube Neutrino Observatory. Both the (stable) three-neutrino and the 3+1 sterile neutrino models are disfavored relative to the unstable sterile neutrino model, though with p values of 2.8% and 0.81%, respectively, we do not observe evidence for 3+1 neutrinos with neutrino decay. The best-fit parameters for the sterile neutrino with decay model from this study are Δm_{41}^{2}=6.7_{-2.5}^{+3.9}  eV^{2}, sin^{2}2θ_{24}=0.33_{-0.17}^{+0.20}, and g^{2}=2.5π±1.5π, where g is the decay-mediating coupling. The preferred regions of the 3+1+decay model from short-baseline oscillation searches are excluded at 90% C.L.

Strong Constraints on Neutrino Nonstandard Interactions from TeV-Scale ν_{μ} Disappearance at IceCube

We report a search for nonstandard neutrino interactions (NSI) using eight years of TeV-scale atmospheric muon neutrino data from the IceCube Neutrino Observatory. By reconstructing incident energies and zenith angles for atmospheric neutrino events, this analysis presents unified confidence intervals for the NSI parameter ε_{μτ}. The best-fit value is consistent with no NSI at a p value of 25.2%. With a 90% confidence interval of -0.0041≤ε_{μτ}≤0.0031 along the real axis and similar strength in the complex plane, this result is the strongest constraint on any NSI parameter from any oscillation channel to date.

Search for Relativistic Magnetic Monopoles with Eight Years of IceCube Data

We present an all-sky 90% confidence level upper limit on the cosmic flux of relativistic magnetic monopoles using 2886 days of IceCube data. The analysis was optimized for monopole speeds between 0.750c and 0.995c, without any explicit restriction on the monopole mass. We constrain the flux of relativistic cosmic magnetic monopoles to a level below 2.0×10^{-19}  cm^{-2} s^{-1} sr^{-1} over the majority of the targeted speed range. This result constitutes the most strict upper limit to date for magnetic monopoles with β≳0.8 and up to β∼0.995 and fills the gap between existing limits on the cosmic flux of nonrelativistic and ultrarelativistic magnetic monopoles.

Measurement of the Fluctuations in the Number of Muons in Extensive Air Showers with the Pierre Auger Observatory

We present the first measurement of the fluctuations in the number of muons in extensive air showers produced by ultrahigh energy cosmic rays. We find that the measured fluctuations are in good agreement with predictions from air shower simulations. This observation provides new insights into the origin of the previously reported deficit of muons in air shower simulations and constrains models of hadronic interactions at ultrahigh energies. Our measurement is compatible with the muon deficit originating from small deviations in the predictions from hadronic interaction models of particle production that accumulate as the showers develop.

eV-Scale Sterile Neutrino Search Using Eight Years of Atmospheric Muon Neutrino Data from the IceCube Neutrino Observatory

The results of a 3+1 sterile neutrino search using eight years of data from the IceCube Neutrino Observatory are presented. A total of 305 735 muon neutrino events are analyzed in reconstructed energy-zenith space to test for signatures of a matter-enhanced oscillation that would occur given a sterile neutrino state with a mass-squared differences between 0.01 and 100  eV^{2}. The best-fit point is found to be at sin^{2}(2θ_{24})=0.10 and Δm_{41}^{2}=4.5  eV^{2}, which is consistent with the no sterile neutrino hypothesis with a p value of 8.0%.

Characteristics of the Diffuse Astrophysical Electron and Tau Neutrino Flux with Six Years of IceCube High Energy Cascade Data

We report on the first measurement of the astrophysical neutrino flux using particle showers (cascades) in IceCube data from 2010-2015. Assuming standard oscillations, the astrophysical neutrinos in this dedicated cascade sample are dominated (∼90%) by electron and tau flavors. The flux, observed in the sensitive energy range from 16 TeV to 2.6 PeV, is consistent with a single power-law model as expected from Fermi-type acceleration of high energy particles at astrophysical sources. We find the flux spectral index to be γ=2.53±0.07 and a flux normalization for each neutrino flavor of ϕ_{astro}=1.66_{-0.27}^{+0.25} at E_{0}=100  TeV, in agreement with IceCube's complementary muon neutrino results and with all-neutrino flavor fit results. In the measured energy range we reject spectral indices γ≤2.28 at ≥3σ significance level. Because of high neutrino energy resolution and low atmospheric neutrino backgrounds, this analysis provides the most detailed characterization of the neutrino flux at energies below ∼100  TeV compared to previous IceCube results. Results from fits assuming more complex neutrino flux models suggest a flux softening at high energies and a flux hardening at low energies (p value ≥0.06). The sizable and smooth flux measured below ∼100  TeV remains a puzzle. In order to not violate the isotropic diffuse gamma-ray background as measured by the Fermi Large Area Telescope, it suggests the existence of astrophysical neutrino sources characterized by dense environments which are opaque to gamma rays.

Features of the Energy Spectrum of Cosmic Rays above 2.5×10^{18} eV Using the Pierre Auger Observatory

We report a measurement of the energy spectrum of cosmic rays above 2.5×10^{18}  eV based on 215 030 events. New results are presented: at about 1.3×10^{19}  eV, the spectral index changes from 2.51±0.03(stat)±0.05(syst) to 3.05±0.05(stat)±0.10(syst), evolving to 5.1±0.3(stat)±0.1(syst) beyond 5×10^{19}  eV, while no significant dependence of spectral features on the declination is seen in the accessible range. These features of the spectrum can be reproduced in models with energy-dependent mass composition. The energy density in cosmic rays above 5×10^{18}  eV is [5.66±0.03(stat)±1.40(syst)]×10^{53}  erg Mpc^{-3}.

Time-Integrated Neutrino Source Searches with 10 Years of IceCube Data

This Letter presents the results from pointlike neutrino source searches using ten years of IceCube data collected between April 6, 2008 and July 10, 2018. We evaluate the significance of an astrophysical signal from a pointlike source looking for an excess of clustered neutrino events with energies typically above ∼1  TeV among the background of atmospheric muons and neutrinos. We perform a full-sky scan, a search within a selected source catalog, a catalog population study, and three stacked Galactic catalog searches. The most significant point in the northern hemisphere from scanning the sky is coincident with the Seyfert II galaxy NGC 1068, which was included in the source catalog search. The excess at the coordinates of NGC 1068 is inconsistent with background expectations at the level of 2.9σ after accounting for statistical trials from the entire catalog. The combination of this result along with excesses observed at the coordinates of three other sources, including TXS 0506+056, suggests that, collectively, correlations with sources in the northern catalog are inconsistent with background at 3.3σ significance. The southern catalog is consistent with background. These results, all based on searches for a cumulative neutrino signal integrated over the 10 years of available data, motivate further study of these and similar sources, including time-dependent analyses, multimessenger correlations, and the possibility of stronger evidence with coming upgrades to the detector.

The administration of intermittent parathyroid hormone affects functional recovery from trochanteric fractured neck of femur: a randomised prospective mixed method pilot study

Aims

We wished to assess the feasibility of a future randomised controlled trial of parathyroid hormone (PTH) supplements to aid healing of trochanteric fractures of the hip, by an open label prospective feasibility and pilot study with a nested qualitative sub study. This aimed to inform the design of a future powered study comparing the functional recovery after trochanteric hip fracture in patients undergoing standard care, versus those who undergo administration of subcutaneous injection of PTH for six weeks.

Patients and Methods

We undertook a pilot study comparing the functional recovery after trochanteric hip fracture in patients 60 years or older, admitted with a trochanteric hip fracture, and potentially eligible to be randomised to either standard care or the administration of subcutaneous PTH for six weeks. Our desired outcomes were functional testing and measures to assess the feasibility and acceptability of the study.

Results

A total of 724 patients were screened, of whom 143 (20%) were eligible for recruitment. Of these, 123 were approached and 29 (4%) elected to take part. However, seven patients did not complete the study. Compliance with the injections was 11 out of 15 (73%) showing the intervention to be acceptable and feasible in this patient population.

Take home message: Only 4% of patients who met the inclusion criteria were both eligible and willing to consent to a study involving injections of PTH, so delivering this study on a large scale would carry challenges in recruitment and retention. Methodological and sample size planning would have to take this into account. PTH administration to patients to enhance fracture healing should still be considered experimental.

Cite this article: Bone Joint J 2016;98-B:840–5.

Right-sided congenital diaphragmatic hernia: A tertiary centre's experience over 25 years

AIMS

To provide analysis on infants treated for right-sided congenital diaphragmatic hernia (RCDH) including mortality, neonatal morbidities, and associated congenital anomalies.

METHODS

We reviewed records of infants admitted with RCDH from 1985 to 2010.

RESULTS

A total of 160 infants with CDH were identified; of them 22 infants had RCDH, 14 (64%) were male and eight (36%) were female. Eleven of the 22 infants died (50%), of which seven (64%) were male, and four (36%) were female. Three infants (13.6%) were diagnosed prenatally, and 19 (86.4%) were diagnosed postnatally. A statistically significant association with mortality was observed for low five minute Apgar score (OR = 8; 95% CI: 1.24-51.5), and high alveolar-arterial gradient >400 (OR = 25.7; 95% CI: 2.2-298.5). Fourteen infants (64%) underwent surgical correction, three (21.4%) infants who underwent surgery died. Three infants were discharged with oxygen supplementation and tube feeding at home, and one on sildenafil. No statistical significance was observed between other variables and mortality/morbidity. We observed a change in practice in relation to timing of surgery allowing stabilisation of patient prior to surgery. Average in-patient stay for RCDH infants was 23.5 days (range: 0-112), compared with the total in-patient mean stay of 10.5 days.

CONCLUSIONS

Low five minute Apgar score, and high alveolar-arterial gradient were significant predictors of mortality. RCDH is associated with high mortality (50%), prolonged length of stay and other anomalies. In recent years, we observed an improving trend for survival.

Functional outcome of fifth metatarsal fractures

INTRODUCTION

Fifth metatarsal fractures are common and the outcome has been reported; however, prospective studies reporting the functional outcome using validated questionnaires are lacking in the literature. The aims of this study were to determine whether fifth metatarsal fractures remain symptomatic in the medium term and whether the fracture type influences outcome.

METHODS

Over the course of a year, 117 patients (62 avulsion fractures, 26 Jones fractures, 29 shaft fractures) were followed up (1 month, 4 months, 12 months), with functional outcome assessed using the Foot Function Index (FFI)- and Short Form 36 (SF36)-validated questionnaires.

RESULTS

The FFI reduced (function improved) over the course of the year from 22.0 (8.4-38.5) at 1 month to 0.0 (0.0-4.2) at 4 months, to 0.0 (0.0-1.3) at 1 year. There was no significant difference in the FFI scores with regard to gender or fracture type. Pain scores were also observed to decline over the year, with no significant differences between fracture types. However, while the severity of pain was low, the numbers of people reporting pain were relatively high. At 1 month, >80% of patients reported ongoing pain (83% avulsion, 88% Jones and 83% shaft), reducing to 38% at 4 months and 28% at 1 year. At final follow-up, 25% with an avulsion fracture, 28% with a Jones fracture and 33% with a shaft fracture reported pain.

CONCLUSIONS

While 25-33% of patients continue to experience pain at 1 year, <10% experience any limitation of their activities. At the final follow-up at 1 year, there were no significant differences in functional outcome by fracture type, gender or patient age. Patients should be advised about the likelihood of ongoing low-level symptoms, even after a year from injury in this previously presumed innocuous injury.

The outcome following fixation of bicondylar tibial plateau fractures

Unstable bicondylar tibial plateau fractures are rare and there is little guidance in the literature as to the best form of treatment. We examined the short- to medium-term outcome of this injury in a consecutive series of patients presenting to two trauma centres. Between December 2005 and May 2010, a total of 55 fractures in 54 patients were treated by fixation, 34 with peri-articular locking plates and 21 with limited access direct internal fixation in combination with circular external fixation using a Taylor Spatial Frame (TSF). At a minimum of one year post-operatively, patient-reported outcome measures including the WOMAC index and SF-36 scores showed functional deficits, although there was no significant difference between the two forms of treatment. Despite low outcome scores, patients were generally satisfied with the outcome. We achieved good clinical and radiological outcomes, with low rates of complication. In total, only three patients (5%) had collapse of the joint of > 4 mm, and metaphysis to diaphysis angulation of 75º, and five patients (9%) with displacement of > 4 mm. All patients in our study went on to achieve full union. This study highlights the serious nature of this injury and generally poor patient-reported outcome measures following surgery, despite treatment by experienced surgeons using modern surgical techniques. Our findings suggest that treatment of complex bicondylar tibial plateau fractures with either a locking plate or a TSF gives similar clinical and radiological outcomes.

Hip precautions after hemiarthroplasty: what is happening in the UK and at what cost?

INTRODUCTION

The aim of this study was to observe current practice of the use of hip precautions following hemiarthroplasty for hip fractures in England and to audit the cost of hip precautions in this patient group.

METHODS

A telephone review was undertaken of all units identified by the National Hip Fracture Database as receiving centres for hip fractures across England to ascertain current practice in the use of hip precautions. A prospective audit of occupational therapy (OT) practice including the cost of equipment provision and OT time was carried out locally.

RESULTS

All 174 units in England were successfully contacted. Practice varied between centres but hip precautions were in use at 78% of centres. Prior to stopping hip precautions at the local hospital, we audited the costs associated with their use. Mean equipment costs per patient decreased by £12 (from £49 to £37, range: £0–£83) and mean OT time per patient decreased by 1.5 hours (from 8 hours to 6.5 hours, range: 1–22 hours) following removal of hip precaution guidelines. A mean of 0.25 days' discharge delay (range: 0–4 days) due to equipment provision was identified prior to removing hip precautions with no discharge delay following.

CONCLUSIONS

This study has highlighted the variation in practice across the country and inconsistency with the advice published by the British Orthopaedic Association and British Geriatrics Society in the ‘Blue Book’ (The Care of Patients with Fragility Fracture). Hip precautions are unnecessary after hemiarthroplasty, cost money both in therapist time and equipment provision and increase the length of hospital stay. Nevertheless, they continue to be used by three-quarters of trauma hospitals in England.

Oral nystatin prophylaxis and neonatal fungal infections

BACKGROUND

The value of antifungal prophylaxis depends partly on the incidence of neonatal fungal infection. We compared the incidence of fungal infection in babies in neonatal units which do and do not give antifungal prophylaxis using oral nystatin.

METHODS

Prospective, multi-centre surveillance study from 1993 to 2006 of invasive fungal infection, defined as positive blood or cerebrospinal fluid culture, in babies <1500 g birth weight in neonatal units in Australia and New Zealand.

RESULTS

There were 118 episodes of invasive fungal infection in 14 778 babies <1500 g, an incidence of 0.80% (95% confidence interval (CI) 0.66 to 0.94%). All infections were due to Candida species, mostly C. albicans (74, 62.7%) and C. parapsilosis (39, 33.1%). The mortality was 16.5%. The incidence was 0.54% (0.38 to 0.70%) for babies <1500 g in units using selective or universal oral nystatin prophylaxis and 1.23% (0.84 to 1.62%) in units using no prophylaxis (p<0.001). The incidence of infection in babies <1000 g was 1.78% (106/5948) (95% CI 1.44 to 2.12%). The incidence was 1.23% (0.92 to 1.54%) for babies <1000 g in units using nystatin prophylaxis and 2.67% (1.97 to 3.37%) in units using no prophylaxis (p<0.001).

CONCLUSIONS

The incidence of neonatal fungal infection was low in Australia and New Zealand, even without antifungal prophylaxis. Antifungal prophylaxis with oral nystatin was associated with a significantly lower incidence of fungal infection compared with no prophylaxis.

Neonatal infections in Asia

OBJECTIVE

To study the epidemiology (including incidence, antibiotic sensitivity and mortality) of neonatal unit infections in countries in Asia.

METHODS

One year prospective study of neonatal infections in eight neonatal units in Asia.

RESULTS

There were 453 episodes of sepsis affecting 394 babies. Mortality from neonatal sepsis was 10.4%, with an incidence of 0.69 deaths/1000 live births. Group B streptococcus was the most common early-onset organism causing 38% of episodes of early-onset (<48 h old) sepsis, with a rate of 0.51 episodes per 1000 live births and a mortality of 22%. Gram-negative bacillary early-onset sepsis occurred at a rate of 0.15 episodes per 1000 live births with a mortality of 12%. There were 406 episodes of late-onset sepsis. The incidence was high at 11.6 per 1000 live births, and mortality was 8.9%. Coagulase-negative staphylococcus caused 34.1% of episodes, whereas Staphylococcus aureus caused only 5.4%. Gram-negative bacilli caused 189 episodes (46.6%). Only 44% of Gram-negative bacilli were sensitive to both gentamicin and a third-generation cephalosporin, whereas 30% were resistant to both antibiotics. Meningitis occurred in 17.2% of episodes of late sepsis, with a mortality of 20%.

CONCLUSIONS

The incidence of late-onset sepsis was higher in Asia than in resource-rich countries, but the organisms isolated and mortality were similar. Over half of all Gram-negative bacilli were antibiotic resistant.

The value of a CT-guided fine needle aspirate in infants with lung abscess

OBJECTIVE

To describe the range of pathogens isolated from a lung abscess in infants less than one year of age. To assess the role of direct culture from the abscess.

METHODS

The two index cases were managed in 2002. An institution-based review was conducted of all infants up to one year of age diagnosed with a lung abscess between 1989 and 2002. Data sources were hospital's disease index and Neonatal Intensive Care Unit Audit database using ICD9 and ICD10 diagnostic codes for 'lung abscess'.

RESULTS

Five infants, under the age of one year, were treated for a lung abscess. In the one case where the abscess was left-sided it was associated with a congenital cystic adenomatoid malformation of the lung. Pathogens were isolated following direct culture of the abscess in four cases. In three cases a single pathogen was isolated: pseudomonas aeruginosa, staphylococcus aureus and haemophilus influenzae. In one case a mixture of escherichia coli, streptococcus milleri and an anaerobe, propionibacteria, were cultured. Antibiotic therapy was directed at the identified pathogen(s) in all four cases. There was no mortality or recurrence.

CONCLUSION

Predisposing factors for a lung abscess in infancy include prematurity, assisted ventilation, congenital lung anomaly and aspiration. Given the range of potential pathogens, direct culture by CT-guided fine needle aspiration is recommended to direct appropriate intravenous medical therapy provided the abscess is located peripherally.

Gastroschisis: determinants of neonatal outcome

This retrospective study elicits information regarding the dependence of neonatal outcome in gastroschisis upon: (1) the mode of delivery, (2) place of birth, (3) time for birth to surgery, (4) method of closure, (5) time from operation to commencement of first enteral feeds. The neonatal intensive care database from five major tertiary centres was used to identify 181 neonates with gastroschisis from 1990 to 2000. There were 8 deaths. There were no significant differences in outcome for infants delivered vaginally (102) versus Caesarean section (79), those born near the tertiary centre (133) as compared to infants born away (48), ones operated within 7 hours (125) compared with those operated after 7 hours (56), with delayed closure (30) versus primary closure (151). Neonates fed within 10 days of operation (85) had significantly lower incidence of sepsis, duration of TPN and hospital stay when compared to those fed after 10 days (96). Early commencement of feeds decreases the incidence of sepsis, duration of total parenteral nutrition (TPN) and hospital stay. Place of delivery, mode of delivery, time to surgery and type of closure do not influence neonatal outcome.

The effects of propranolol on cognitive function and quality of life: a randomized trial among patients with diastolic hypertension

PURPOSE

We sought to determine whether propranolol has adverse effects on cognitive function, depressive symptoms, and sexual function in patients treated for diastolic hypertension.

SUBJECTS AND METHODS

We performed a placebo-controlled trial among 312 men and women, 22 to 59 years of age, who had untreated diastolic hypertension (90 to 104 mm Hg). Patients were randomly assigned to treatment with propranolol (80 to 400 mg/day) or matching placebo tablets. Thirteen tests of cognitive function were assessed at baseline, 3 months, and 12 months. Five tests measured reaction time to, or accuracy in, interpreting visual stimuli; one test measured the ability to acquire, reproduce, and change a set of arbitrary stimulus-response sets; and seven tests measured memory or learning verbal information. Depressive symptoms and sexual function were assessed by questionnaires at baseline and 12 months.

RESULTS

There were no significant differences by treatment assignment for 11 of the 13 tests of cognitive function at either 3 or 12 months of follow-up. Compared with placebo, participants treated with propranolol had slightly fewer correct responses at 3 months (33 +/- 3 [mean +/- SD] versus 34 +/- 2, P = 0.02) and slightly more errors of commission at 3 months (4 +/-5 versus 3 +/- 3, P = 0.04) and at 12 months (4 +/- 4 versus 3 +/- 3, P = 0.05). At 12 months, depressive symptoms and sexual function and desire did not differ by treatment assignment.

CONCLUSIONS

Treatment of hypertension with propranolol had limited adverse effects on tests of cognitive function that were of questionable clinical relevance, and there were no documented adverse effects on depressive symptoms or sexual function. Selection of beta-blockers for treatment of hypertension should be based on other factors.

Effects of cotinine on information processing in nonsmokers

Cotinine, the major proximate metabolite of nicotine, is present in smokers in higher concentrations and for a longer time than nicotine, yet its effects on information processing have not previously been reported. We studied the cognitive effects of cotinine in non-smokers. Sixteen subjects were tested on three doses of cotinine (0.5, 1.0, and 1.5 mg cotinine base/kg), and placebo, on a choice reaction time (RT) task and on a verbal recall task with short and long lists. Cotinine significantly impaired recall on the long list and displayed non-significant but generally consistent dose-related slowing of RT and N100 latency. The acute effects of cotinine were small, and probably do not account for the cognitive deficits observed in tobacco withdrawal, although the cognitive effects of chronic cotinine administration need to be investigated.

Medical futility and the social context

The concept of medical futility has come to be seen in some quarters as a value-neutral trump card when dealing with issues of power and conflicting values in medicine. I argue that this concept is potentially useful, but only in a social context that provides a normative framework for its use. This social context needs to include a broad consensus about the purpose of medicine and the nature of the physician-patient relationship.

Reasons for increased incidence of tuberculosis

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Increasing incidence of tuberculosis in England and Wales: a study of the likely causes

OBJECTIVE

To examine factors responsible for the recent increase in tuberculosis in England and Wales.

DESIGN

Study of the incidence of tuberculosis (a) in the 403 local authority districts in England and Wales, ranked according to Jarman score, and (b) in one deprived inner city district, according to ethnic origin and other factors.

SETTING

(a) England and Wales 1980-92, and (b) the London borough of Hackney 1986-93.

MAIN OUTCOME MEASURE

Age and sex adjusted rate of tuberculosis.

RESULTS

In England and Wales notifications of tuberculosis increased by 12% between 1988 and 1992. The increase was 35% in the poorest 10th of the population and 13% in the next two; and in the remaining 70% there was no increase. In Hackney the increase affected traditionally high risk and low risk ethnic groups to a similar extent. In the "low risk" white and West Indian communities the incidence increased by 58% from 1986-8 (78 cases) to 1991-3 (123), whereas in residents of Indian subcontinent origin the increase was 41% (from 51 cases to 72). Tuberculosis in recently arrived immigrants--refugees (11% of the Hackney population) and Africans (6%)--accounted for less than half of the overall increase, and the proportion of such residents was much higher than in most socioeconomically deprived districts. The local increase was not due to an increase in the proportion of cases notified, to HIV infection, nor to an increase in homeless people.

CONCLUSIONS

The national rise in tuberculosis affects only the poorest areas. Within one such area all residents (white and established ethnic minorities) were affected to a similar extent. The evidence indicates a major role for socioeconomic factors in the increase in tuberculosis and only a minor role for recent immigration from endemic areas.

The effect of D-amphetamine, clonidine, and yohimbine on human information processing

Twelve subjects were tested with D-amphetamine, yohimbine, clonidine, and a placebo on a task with two levels of stimulus and two levels of response complexity. The purpose of this study was to test the hypothesis that noradrenergic drugs affect early stimulus processes. D-amphetamine speeded reaction time (RT), clonidine slowed it, and yohimbine had no effect. D-amphetamine and yohimbine decreased N1 latency and clonidine increased it. D-amphetamine and yohimbine decreased P3 latency and clonidine increased it but, in each case, only when latency estimates were based on single trials, not on averages. D-amphetamine's effect on RT, not P3, as measured by the average, is consistent with previous results. Single trial measures appear more sensitive. Speeding of N1 and single-trial P3 data indicate that noradrenergic drugs affect processing of early (visual) information. D-amphetamine's speeding of single-trial P3 estimates was attributed to its noradrenergic actions. Yohimbine's speeding of P3 without changing RT is consistent with neural net (parallel) simulations but not with a serial model. These findings support the assumption that different neurotransmitters modulate specific cognitive processes.

A low dose of subcutaneous nicotine improves information processing in non-smokers

Many studies have found that cigarette smoking or nicotine improves mental functioning in abstinent smokers. An unresolved issue is whether this improvement is due primarily to a direct facilitation of performance or to relief of the impairment caused by nicotine withdrawal. We evaluated the performance of 12 non-smokers before and twice (15 and 45 min) after a subcutaneous injection of 0.8 mg nicotine, 0.8 ml saline, and a control no treatment, on a choice reaction time (RT) task. Each treatment was given on a separate day; the control day was given on the first session. The order of nicotine and saline was balanced between subjects, and injections were given double-blind. The RT task manipulated stimulus and response processing. These manipulations consisted of two levels of stimulus complexity and two levels of response complexity, resulting in four task conditions. These manipulations along with latency measures of the event-related potential were used to identify the components of processing that mediated nicotine's effects on performance. During each active drug session blood nicotine levels, cardiovascular, and subjective responses were measured before and after each of the three tests (pre-drug, 15 min and 45 min post-drug). For the information processing measures only the comparisons of the pre- and 15-min post-test showed significant drug effects. Nicotine compared to saline significantly increased the number of responses at the fast end of the RT distribution. However, there were no changes in accuracy. Nicotine also speeded mean RT compared with saline or the control day, but the effects were only significant for the control-nicotine comparison.(ABSTRACT TRUNCATED AT 250 WORDS)

Drugs and human information processing

Human performance on a choice-reaction time task (Eriksen task) has been simulated by a neural network. In simulations, the network captures many features of normal performance. In addition, changing gain in different layers produces changes that simulate different drug-induced changes. Data from a similar choice-reaction time task have been reanalyzed to test some of the predictions derived from changing gain in different layers. Clonidine antagonizes norepinephrine and acetylcholine activities and changes speed-accuracy tradeoff (i.e., increased frequency of errors at any specified reaction time). That is predicted when gain is reduced in lower layers (attention layer and input layer) of the network. By contrast, manipulating dopamine activity (with pimozide and amphetamine) changes reaction time without changing speed-accuracy tradeoff functions. That is predicted when gain is changed in the output layer of the network.

Cholinergic activity and constraints on information processing

In humans, close relationships are found between cholinergic activity and constraints placed on information processing operations. This is true for all operations where the effects of cholinergic activity have been studied. Studies of vigilance, memory, problem solving, stimulus processing and response processing are cited as illustrations. These studies suggest the hypothesis that cholinergic activity controls constraints in all information processing operations. Alternative hypotheses are proposed and experimental tests are suggested.

Scopolamine effects on visual information processing, attention, and event-related potential map latencies

We measured performance and event-related brain potential (ERP) map latencies in 12 subjects during four visual discrimination tasks to compare the timing of scopolamine effects on information processing and attention. "Topographic component recognition" found ERP map latencies at times of best fit with a component model map. This "common topography" criterion minimized topographic differences among conditions to facilitate latency interpretations. Scopolamine slowed N1 latency in all tasks, and P3 and reaction time in some tasks. The drug delayed responses to easy targets more than to hard targets. It also induced a disproportionate N1 delay for unilateral high spatial frequency gratings. Both effects reflect a scopolamine-induced impairment when processing targets that usually capture attention. Scopolamine also impaired accuracy for unilateral high spatial frequency gratings, and for gratings presented at probable locations, confirming and extending previous findings. Scopolamine-induced P1 and N1 delays showed that visual processing was affected. Several results were inconsistent with a serial stage model. We suggest that scopolamine both delays selected processes and impairs a processing mode based on automatic capture of attention, inducing more serial processing.

The effects of mild diastolic hypertension on the results of tests of cognitive function in adults 22 to 59 years of age

OBJECTIVE

To test the hypothesis that mild diastolic hypertension (90 to 104 mm Hg) may induce asymptomatic impairment of cognitive function.

DESIGN

Cross-sectional.

SETTING

Community participants recruited to a university-based ambulatory care center.

PARTICIPANTS

Three hundred twelve men and women with untreated essential hypertension and 47 normotensive subjects, 22 to 59 years of age.

MEASUREMENTS AND MAIN RESULTS

Cognitive function tests measured reaction time to and accuracy in interpreting predetermined visual stimuli, the ability to acquire, reproduce, and change a set of arbitrary stimulus-response associations, and memory and learning of verbal information. These tests were selected to detect subtle differences in performances as opposed to differentiating neurologically normal persons from brain-damaged persons. After controlling for age, gender, and education, results showed that there was no significant difference between the normotensive and hypertensive subjects in two measures of reaction time to and four measures of accuracy in interpreting predetermined visual stimuli, in the measure of arbitrary stimulus-response associations, or in seven memory and learning variables. Although confidence intervals for the differences between means were wide, clinically significant differences were not likely to be present. Younger age was associated with faster reaction times, fewer errors, and better performance on memory and learning tasks, independent of diastolic blood pressure.

CONCLUSIONS

The few detectable effects of untreated mild hypertension on cognitive function reported in the literature may be due to chance and are of questionable clinical significance.

Clonidine and scopolamine: differences and similarities in how they change human information processing

1. Humans have been tested on a choice reaction time task designed to disclose interactions between stimulus complexity and drug effect. 2. Tests were carried out using oral scopolamine (1.2 mg) and clonidine (0.2 mg). 3. Reaction times and event related potentials were measured. 4. Both drugs slowed reaction time and the N1 component of the ERP. 5. SCOP slows RTs to easy-to-discriminate stimuli more than RTs to harder stimuli. Its effect on P3 is the same for both types of stimuli. 6. CLON tends to slow P3 latencies to easy stimuli more than P3 latencies to harder stimuli, while the RT slowing is almost identical for both types of stimuli.

Beyond drug effects and dependent variables: the use of the Poisson-Erlang model to assess the effects of D-amphetamine on information processing

Several studies have shown that d-amphetamine (DAMP) speeds mean reaction time (RT). However, the use of mean RT may obscure important aspects of the drug response. Therefore we applied the Poisson-Erlang (PE) stochastic model of choice reaction time proposed by Pieters (1985) to the RT distribution. This model proposes that the RT distribution is generated by two states: Processing (P) and Distraction (D). RT represents the sum of the time spent in each of these states. P is the time taken to complete a set of cognitive operations which are required to give a correct response. D represents the time taken by all other activities. RTs were collected using a task (SERS) in which stimulus and response complexity each had two levels, easy and hard. Subjects were tested pre- and postdrug. Drug conditions were: placebo, 10 mg d-amphetamine (DAMP), 4 mg of the dopamine agonist, pimozide, and a combination of DAMP and pimozide (COMBO). Parameters of the model were derived using methods described by Pieters. Four measures were analyzed: Processing Time (PT); Mean Time per distraction (XTD); Distraction Rate (DR); and Total Distraction Time per trial (TDT). Mean RT is also presented. Analyses of the effects of task conditions on the parameters of the model were made using the predrug sessions. Mean RT was increased by both stimulus and response complexities as was PT. TDT was increased by the task conditions. The PE measures did not change over days. DAMP speeded mean RT. However, this effect did not interact with the task factors. DAMP speeded processing and reduced distraction. Processing was speeded only in the hard response condition, distraction time was reduced only in the easy response condition. The results indicate that the PE model can be successfully applied to fast RT tasks. More importantly, the parameters of the model revealed important pharmacological effects that were not apparent in mean RT. DAMP speeds cognitive operations related to motor preparation and reduces the effects of distraction. Consistent with past studies there are no indications that DAMP interacted with stimulus processing. The distraction effect appears to be mediated by an increase in the rate of distraction and a decrease in the average time of these distractions.

The effects of clonidine and yohimbine on human information processing

The effects of clonidine and yohimbine on human information processing were tested in six normal volunteers ages 18-30 years. Subjects were tested in a pre-post design with sessions conducted at weekly intervals. Three drug conditions were: Placebo (lactose), 0.2 mg clonidine, and 30 mg yohimbine. Two choice reaction time (RT) tasks were used. One was a stimulus evaluation-response selection task (SERS) that has been shown to be sensitive to d-amphetamine, methylphenidate and scopolamine. The other task was to assess stimulus pre-processing and used spatial frequency as a discriminative stimulus. The principle finding was that clonidine slowed RT; this effect was significant for both tasks. In contrast, yohimbine tended to speed RT, but the effects were significant only for the spatial frequency task on some analyses while not for others. RTs to high spatial frequency stimuli were speeded more than for low spatial frequency. The effects of these two NE drugs were compared with findings with d-amphetamine and scopolamine and interpreted within the framework of a serial information processing model proposed by Callaway (1983). Specifically, it is suggested that yohimbine and clonidine affect an early pre-processing stage.

The teenage coeliac: follow up study of 102 patients

Over a 10 year period a total of 102 teenage patients with coeliac disease were assessed on transfer from paediatric hospitals to an adult clinic. Fifty seven patients said they were on a strict gluten free diet; 36 were semistrict, and nine admitted to eating a normal diet. Jejunal mucosal abnormalities, however, suggested that many patients on the 'strict' diet were actually consuming gluten. All patients were well with biochemical parameters within the normal range. Height percentiles were not significantly different from the normal population but patients, as a group, were significantly lighter.

The effects of stimulant drugs on information processing in elderly adults

The effects of stimulant drug on information processing in elderly adults was studied. In Experiment 1, the effect of methylphenidate (MP) was examined in 8 young and 8 elderly women using a task (SERS) in which stimulus and response complexities were varied. MP speeded processing in the young but not in the elderly women. A second experiment was then conducted to isolate the age-stimulant effects. In Experiment 2, the effects of MP and 10 mg of d-amphetamine (DAMP) were studied in 12 young and 12 elderly men on different types of information processing. Stimulants changed performance on a continuous performance task in both groups. Both stimulants speeded processing on SERS in young, but not in elderly men. MP, however, speeded processing in both groups on a response processing task. The findings suggest that stimulants act on response processing and there appear to be several such processes. Some of these stages decline with age whereas others do not.

Effects of oral scopolamine on human stimulus evaluation

In a previous study of the effect of age on information processing, both age and stimulus complexity slowed reaction time (RT) and the latency of the P300 component of the brain event-related potential (ERP). The aim of the present study was to compare the effects of scopolamine (an anticholinergic) with the previously noted effects of age. The choice of scopolamine was prompted by current hypotheses concerning decline in cholinergic function with age. Twelve adult women were studied on a battery of tasks before and after scopolamine in oral doses of 0.0 (placebo), 0.6 and 1.2 mg. Reaction times (RT) and event-related potentials (ERP) were measured. The principal task was one that combined two levels of stimulus complexity and two levels of response difficulty to provide four subtasks. Scopolamine slowed RT and P300 as had age, but scopolamine slowed responses to simple stimuli more than responses to complex stimuli. Scopolamine effects on other tasks in the battery were small but consistent with an action of scopolamine on an early stimulus preprocessing stage that is independent of a stimulus evaluation stage that is also affected by age.

The effect of methylphenidate on information processing

Models of information processing currently popular in cognitive psychology divide the reaction process into a series of discrete separable stages. The distinction between one stage and another is verified by the additive factors method (AFM) as defined by Sternberg (1969). Task factors that do not interact with each other are inferred to affect different stages. The distinction between stimulus evaluation stages and response selection stages has been supported by brain event related potential (ERP) studies. The latency of the P300 component of the ERP is sensitive to changes in stimulus complexity but not to to changes in response complexity. The focus of this research is to determine the effects of stimulant drugs on stages of information processing using both reaction time (RT) and P300 latency within an AFM framework. Four doses of methylphenidate (MP) were used in a within-subjects design to examine the effects of MP on stimulus and response processing. We found that MP speeds RT, and that this effect does not interact with the effect of stimulus complexity on RT. MP dose interacts with response complexity, the dose for optimal speeding varying with the level of complexity. The latency of P300 is increased by stimulus complexity, and not by response complexity, nor is it affected by MP. These results show that the stimulant drug acts on processes involved in response selection, rather than in stimulus evaluation. Individual differences in drug response are dose dependent, but also point to an effect on response processing.

Effects of two doses of methylphenidate on verbal information processing in hyperactive children

Nine hyperactive children participated in three sessions. During each they were given one of three drugs (placebo, 10 mg, or 21 mg of methylphenidate) in a double-blind crossover study. Following drug administration they were tested on three cognitive tasks. For one task, structural, acoustic, or semantic degrees of encoding of verbal information were induced. Memory for the verbal information was then tested. The 10-mg dose resulted in overall improvement of word recognition and recall. The 21-mg dose did not result in improvement. Amount of improvement was not related to degree of encoding of words. Two other tasks, learning a list of words and visual search of letters from a briefly presented display, were not affected by either the 10- or 21-mg dose. The results indicate that verbal learning can be facilitated by a low dose of methylphenidate but that the dose range may be narrow. Also, certain individuals did not respond favorably to either dose. In discussing the results, the possibility is presented that methylphenidate-induced facilitation may be restricted to certain types of learning or certain methods of assessing retrieval of information.