Temporal Structures in Positron Spectra and Charge-Sign Effects in Galactic Cosmic Rays

We present the precision measurements of 11 years of daily cosmic positron fluxes in the rigidity range from 1.00 to 41.9 GV based on 3.4×10^{6} positrons collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. The positron fluxes show distinctly different time variations from the electron fluxes at short and long timescales. A hysteresis between the electron fluxes and the positron fluxes is observed with a significance greater than 5σ at rigidities below 8.5 GV. On the contrary, the positron fluxes and the proton fluxes show similar time variation. Remarkably, we found that positron fluxes are modulated more than proton fluxes with a significance greater than 5σ for rigidities below 7 GV. These continuous daily positron fluxes, together with AMS daily electron, proton, and helium fluxes over an 11-year solar cycle, provide unique input to the understanding of both the charge-sign and mass dependencies of cosmic rays in the heliosphere.

Properties of Cosmic-Ray Sulfur and Determination of the Composition of Primary Cosmic-Ray Carbon, Neon, Magnesium, and Sulfur: Ten-Year Results from the Alpha Magnetic Spectrometer

We report the properties of primary cosmic-ray sulfur (S) in the rigidity range 2.15 GV to 3.0 TV based on 0.38×10^{6} sulfur nuclei collected by the Alpha Magnetic Spectrometer experiment (AMS). We observed that above 90 GV the rigidity dependence of the S flux is identical to the rigidity dependence of Ne-Mg-Si fluxes, which is different from the rigidity dependence of the He-C-O-Fe fluxes. We found that, similar to N, Na, and Al cosmic rays, over the entire rigidity range, the traditional primary cosmic rays S, Ne, Mg, and C all have sizeable secondary components, and the S, Ne, and Mg fluxes are well described by the weighted sum of the primary silicon flux and the secondary fluorine flux, and the C flux is well described by the weighted sum of the primary oxygen flux and the secondary boron flux. The primary and secondary contributions of the traditional primary cosmic-ray fluxes of C, Ne, Mg, and S (even Z elements) are distinctly different from the primary and secondary contributions of the N, Na, and Al (odd Z elements) fluxes. The abundance ratio at the source for S/Si is 0.167±0.006, for Ne/Si is 0.833±0.025, for Mg/Si is 0.994±0.029, and for C/O is 0.836±0.025. These values are determined independent of cosmic-ray propagation.

Temporal Structures in Electron Spectra and Charge Sign Effects in Galactic Cosmic Rays

We present the precision measurements of 11 years of daily cosmic electron fluxes in the rigidity interval from 1.00 to 41.9 GV based on 2.0×10^{8} electrons collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. The electron fluxes exhibit variations on multiple timescales. Recurrent electron flux variations with periods of 27 days, 13.5 days, and 9 days are observed. We find that the electron fluxes show distinctly different time variations from the proton fluxes. Remarkably, a hysteresis between the electron flux and the proton flux is observed with a significance of greater than 6σ at rigidities below 8.5 GV. Furthermore, significant structures in the electron-proton hysteresis are observed corresponding to sharp structures in both fluxes. This continuous daily electron data provide unique input to the understanding of the charge sign dependence of cosmic rays over an 11-year solar cycle.

Effectiveness of diagnosis and early treatment of ocular motility alterations in premature infants

Objective

Prematurity often results in important developmental sequelae of brain structures, particularly those involved in processing visual information, such as the optic nerve, primary visual cortex and visuomotor integration areas. The aim of this study is to analyse the functionality of the sensory and motor pathways of the visual system by means of an orthoptic-ophthalmological assessment.

Materials and methods

In this retrospective study, 151 records were examined, covering a period from 2000 to 2020, of preterm patients with gestational age < 32 weeks and birth weight ≤ 1,500 g up to an average age of about 8 years, referred to the Centre for Paediatric Ophthalmology and Strabology of the Ophthalmology Clinic of the Policlinico Umberto I, La Sapienza University of Rome, who underwent a complete ophthalmological and orthoptic assessment including the following tests measurement of ocular deviations according to the Hirschberg method, Lang I-II test, Titmus Stereotest, objective convergence assessment and ocular motility examination.

Results

From the charts reviewed, 24.5% (37/151) of patients had Retinopathy of the Premature (ROP); while 38% of the whole sample (57/151) had strabismic amblyopia, of the latter only 31.5% (18/57) had ROP. In 8% of patients (12/151) the stereoscopic sense was absent, in 45% (8/151) stereopsis was gross (> 60 seconds of arc). In addition, 20.52 % (31/151) had a manifest eye deviation. 7.28% (11/151) had hypermetropia in the right eye (RE); 7.95% (12/151) hypermetropia in the left eye (OS); 3.31% of the patients (5/151) had myopia in the RE; 2% (3/151), myopia in the left eye (LE). In addition, the study of ocular motility revealed varying degrees of alteration poorly correlated with prematurity status.

Conclusion

It was found that amblyopia, stereopsis and objective convergence are more affected by ROP than strabismus, refractive defects and ocular motility, indicating that premature children are particularly susceptible to ophthalmological and orthoptical alterations.

Properties of Daily Helium Fluxes

We present the precision measurement of 2824 daily helium fluxes in cosmic rays from May 20, 2011 to October 29, 2019 in the rigidity interval from 1.71 to 100 GV based on 7.6×10^{8} helium nuclei collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. The helium flux and the helium to proton flux ratio exhibit variations on multiple timescales. In nearly all the time intervals from 2014 to 2018, we observed recurrent helium flux variations with a period of 27 days. Shorter periods of 9 days and 13.5 days are observed in 2016. The strength of all three periodicities changes with time and rigidity. In the entire time period, we found that below ∼7  GV the helium flux exhibits larger time variations than the proton flux, and above ∼7  GV the helium to proton flux ratio is time independent. Remarkably, below 2.4 GV a hysteresis between the helium to proton flux ratio and the helium flux was observed at greater than the 7σ level. This shows that at low rigidity the modulation of the helium to proton flux ratio is different before and after the solar maximum in 2014.

Periodicities in the Daily Proton Fluxes from 2011 to 2019 Measured by the Alpha Magnetic Spectrometer on the International Space Station from 1 to 100 GV

We present the precision measurement of the daily proton fluxes in cosmic rays from May 20, 2011 to October 29, 2019 (a total of 2824 days or 114 Bartels rotations) in the rigidity interval from 1 to 100 GV based on 5.5×10^{9} protons collected with the Alpha Magnetic Spectrometer aboard the International Space Station. The proton fluxes exhibit variations on multiple timescales. From 2014 to 2018, we observed recurrent flux variations with a period of 27 days. Shorter periods of 9 days and 13.5 days are observed in 2016. The strength of all three periodicities changes with time and rigidity. The rigidity dependence of the 27-day periodicity is different from the rigidity dependences of 9-day and 13.5-day periods. Unexpectedly, the strength of 9-day and 13.5-day periodicities increases with increasing rigidities up to ∼10  GV and ∼20  GV, respectively. Then the strength of the periodicities decreases with increasing rigidity up to 100 GV.

Role of heparin prophylaxis at different doses in patients with COVID-19 and respiratory failure: a systematic review and meta-analysis

Background

Venous thromboembolism (VTE) is common in patients with coronavirus disease-2019 (COVID-19). The use of heparin at higher doses than prophylactic is advocated, but the optimal regimens remain unknown due to the balance between prevention of thromboembolic events and bleeding risks.

Objective

To systematically review and perform a meta-analysis aimed at evaluating the risk of VTE and of major bleeding (MB) in patients with respiratory failure due to COVID-19 according to heparin doses.

Methods

We performed a systematic search in MEDLINE up until 22 March 2021. Studies on patients with respiratory failure due to COVID-19 were included if reported on study outcomes according to standard prophylactic and to higher heparin doses and included more than 10 patients. Study primary outcome was VTE; secondary outcomes were MB, all-cause death, fatal bleeding and fatal pulmonary embolism (PE).

Results

Overall, 2 randomized and 16 observational studies were selected (3458 patients). In 13 studies (2492 patients) VTE events were similar in patients receiving standard prophylaxis or higher heparin doses (RR 1.06, 95% CI 0.58–1.95, I2 87%; only randomized studies RR 1.72, 95% CI 0.78–3.81, I2 54%). 16 studies (3174) reporting on MB and showed a significant reduction in favor of standard heparin prophylaxis (RR 0.39, 95% CI 0.28–0.53, I2 8%). No differences were observed for overall mortality according to heparin doses (RR 1.11, 95% CI 0.88–1.40, I2 68%; in 8 studies, 2448 patients). Similarly, no differences were observed for fatal bleedings and fatal PEs.

In the subanalysis of studies reporting only on intensive care unit patients (ICU) an increase in the risk of VTE (RR 1.86, 95% CI 1.28–2.72, I2 18%) and a reduction on the risk of MB (RR 0.60, 95% CI 0.40–0.90, I2 0%) were observed in patients receiving standard heparin doses compared to higher doses. Overall mortality was similar (RR 1.09, 95% CI 0.86–1.39, I2 64%).

Conclusion

Different doses of heparin prophylaxis seem to not affect the risk of VTE in the overall patients with COVID-19 and respiratory failure. In studies reporting only on ICU patients the risk of VTE was lower when higher heparin doses were used compared to standard doses, but with no advantage in overall death and with an increase of MBs.

Funding Acknowledgement

Type of funding sources: None.

Erratum: Properties of a New Group of Cosmic Nuclei: Results from the Alpha Magnetic Spectrometer on Sodium, Aluminum, and Nitrogen [Phys. Rev. Lett. 127, 021101 (2021)]

This corrects the article DOI: 10.1103/PhysRevLett.127.021101.

Properties of a New Group of Cosmic Nuclei: Results from the Alpha Magnetic Spectrometer on Sodium, Aluminum, and Nitrogen

We report the properties of sodium (Na) and aluminum (Al) cosmic rays in the rigidity range 2.15 GV to 3.0 TV based on 0.46 million sodium and 0.51 million aluminum nuclei collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. We found that Na and Al, together with nitrogen (N), belong to a distinct cosmic ray group. In this group, we observe that, similar to the N flux, both the Na flux and Al flux are well described by the sums of a primary cosmic ray component (proportional to the silicon flux) and a secondary cosmic ray component (proportional to the fluorine flux). The fraction of the primary component increases with rigidity for the N, Na, and Al fluxes and becomes dominant at the highest rigidities. The Na/Si and Al/Si abundance ratios at the source, 0.036±0.003 for Na/Si and 0.103±0.004 for Al/Si, are determined independent of cosmic ray propagation.

Properties of Heavy Secondary Fluorine Cosmic Rays: Results from the Alpha Magnetic Spectrometer

Precise knowledge of the charge and rigidity dependence of the secondary cosmic ray fluxes and the secondary-to-primary flux ratios is essential in the understanding of cosmic ray propagation. We report the properties of heavy secondary cosmic ray fluorine F in the rigidity R range 2.15 GV to 2.9 TV based on 0.29 million events collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. The fluorine spectrum deviates from a single power law above 200 GV. The heavier secondary-to-primary F/Si flux ratio rigidity dependence is distinctly different from the lighter B/O (or B/C) rigidity dependence. In particular, above 10 GV, the F/Si/B/O ratio can be described by a power law R^{δ} with δ=0.052±0.007. This shows that the propagation properties of heavy cosmic rays, from F to Si, are different from those of light cosmic rays, from He to O, and that the secondary cosmic rays have two classes.

Properties of Iron Primary Cosmic Rays: Results from the Alpha Magnetic Spectrometer

We report the observation of new properties of primary iron (Fe) cosmic rays in the rigidity range 2.65 GV to 3.0 TV with 0.62×10^{6} iron nuclei collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. Above 80.5 GV the rigidity dependence of the cosmic ray Fe flux is identical to the rigidity dependence of the primary cosmic ray He, C, and O fluxes, with the Fe/O flux ratio being constant at 0.155±0.006. This shows that unexpectedly Fe and He, C, and O belong to the same class of primary cosmic rays which is different from the primary cosmic rays Ne, Mg, and Si class.

Properties of Neon, Magnesium, and Silicon Primary Cosmic Rays Results from the Alpha Magnetic Spectrometer

We report the observation of new properties of primary cosmic rays, neon (Ne), magnesium (Mg), and silicon (Si), measured in the rigidity range 2.15 GV to 3.0 TV with 1.8×10^{6}  Ne, 2.2×10^{6}  Mg, and 1.6×10^{6}  Si nuclei collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. The Ne and Mg spectra have identical rigidity dependence above 3.65 GV. The three spectra have identical rigidity dependence above 86.5 GV, deviate from a single power law above 200 GV, and harden in an identical way. Unexpectedly, above 86.5 GV the rigidity dependence of primary cosmic rays Ne, Mg, and Si spectra is different from the rigidity dependence of primary cosmic rays He, C, and O. This shows that the Ne, Mg, and Si and He, C, and O are two different classes of primary cosmic rays.

Properties of Cosmic Helium Isotopes Measured by the Alpha Magnetic Spectrometer

Precision measurements by the Alpha Magnetic Spectrometer (AMS) on the International Space Station of ^{3}He and ^{4}He fluxes are presented. The measurements are based on 100 million ^{4}He nuclei in the rigidity range from 2.1 to 21 GV and 18 million ^{3}He from 1.9 to 15 GV collected from May 2011 to November 2017. We observed that the ^{3}He and ^{4}He fluxes exhibit nearly identical variations with time. The relative magnitude of the variations decreases with increasing rigidity. The rigidity dependence of the ^{3}He/^{4}He flux ratio is measured for the first time. Below 4 GV, the ^{3}He/^{4}He flux ratio was found to have a significant long-term time dependence. Above 4 GV, the ^{3}He/^{4}He flux ratio was found to be time independent, and its rigidity dependence is well described by a single power law ∝R^{Δ} with Δ=-0.294±0.004. Unexpectedly, this value is in agreement with the B/O and B/C spectral indices at high energies.

Towards Understanding the Origin of Cosmic-Ray Electrons

Precision results on cosmic-ray electrons are presented in the energy range from 0.5 GeV to 1.4 TeV based on 28.1×10^{6} electrons collected by the Alpha Magnetic Spectrometer on the International Space Station. In the entire energy range the electron and positron spectra have distinctly different magnitudes and energy dependences. The electron flux exhibits a significant excess starting from 42.1_{-5.2}^{+5.4}  GeV compared to the lower energy trends, but the nature of this excess is different from the positron flux excess above 25.2±1.8  GeV. Contrary to the positron flux, which has an exponential energy cutoff of 810_{-180}^{+310}  GeV, at the 5σ level the electron flux does not have an energy cutoff below 1.9 TeV. In the entire energy range the electron flux is well described by the sum of two power law components. The different behavior of the cosmic-ray electrons and positrons measured by the Alpha Magnetic Spectrometer is clear evidence that most high energy electrons originate from different sources than high energy positrons.

Towards Understanding the Origin of Cosmic-Ray Positrons

Precision measurements of cosmic ray positrons are presented up to 1 TeV based on 1.9 million positrons collected by the Alpha Magnetic Spectrometer on the International Space Station. The positron flux exhibits complex energy dependence. Its distinctive properties are (a) a significant excess starting from 25.2±1.8  GeV compared to the lower-energy, power-law trend, (b) a sharp dropoff above 284_{-64}^{+91}  GeV, (c) in the entire energy range the positron flux is well described by the sum of a term associated with the positrons produced in the collision of cosmic rays, which dominates at low energies, and a new source term of positrons, which dominates at high energies, and (d) a finite energy cutoff of the source term of E_{s}=810_{-180}^{+310}  GeV is established with a significance of more than 4σ. These experimental data on cosmic ray positrons show that, at high energies, they predominantly originate either from dark matter annihilation or from other astrophysical sources.

Observation of Complex Time Structures in the Cosmic-Ray Electron and Positron Fluxes with the Alpha Magnetic Spectrometer on the International Space Station

We present high-statistics, precision measurements of the detailed time and energy dependence of the primary cosmic-ray electron flux and positron flux over 79 Bartels rotations from May 2011 to May 2017 in the energy range from 1 to 50 GeV. For the first time, the charge-sign dependent modulation during solar maximum has been investigated in detail by leptons alone. Based on 23.5×10^{6} events, we report the observation of short-term structures on the timescale of months coincident in both the electron flux and the positron flux. These structures are not visible in the e^{+}/e^{-} flux ratio. The precision measurements across the solar polarity reversal show that the ratio exhibits a smooth transition over 830±30 days from one value to another. The midpoint of the transition shows an energy dependent delay relative to the reversal and changes by 260±30 days from 1 to 6 GeV.

Precision Measurement of Cosmic-Ray Nitrogen and its Primary and Secondary Components with the Alpha Magnetic Spectrometer on the International Space Station

A precision measurement of the nitrogen flux with rigidity (momentum per unit charge) from 2.2 GV to 3.3 TV based on 2.2×10^{6} events is presented. The detailed rigidity dependence of the nitrogen flux spectral index is presented for the first time. The spectral index rapidly hardens at high rigidities and becomes identical to the spectral indices of primary He, C, and O cosmic rays above ∼700  GV. We observed that the nitrogen flux Φ_{N} can be presented as the sum of its primary component Φ_{N}^{P} and secondary component Φ_{N}^{S}, Φ_{N}=Φ_{N}^{P}+Φ_{N}^{S}, and we found Φ_{N} is well described by the weighted sum of the oxygen flux Φ_{O} (primary cosmic rays) and the boron flux Φ_{B} (secondary cosmic rays), with Φ_{N}^{P}=(0.090±0.002)×Φ_{O} and Φ_{N}^{S}=(0.62±0.02)×Φ_{B} over the entire rigidity range. This corresponds to a change of the contribution of the secondary cosmic ray component in the nitrogen flux from 70% at a few GV to <30% above 1 TV.

Observation of Fine Time Structures in the Cosmic Proton and Helium Fluxes with the Alpha Magnetic Spectrometer on the International Space Station

We present the precision measurement from May 2011 to May 2017 (79 Bartels rotations) of the proton fluxes at rigidities from 1 to 60 GV and the helium fluxes from 1.9 to 60 GV based on a total of 1×10^{9} events collected with the Alpha Magnetic Spectrometer aboard the International Space Station. This measurement is in solar cycle 24, which has the solar maximum in April 2014. We observed that, below 40 GV, the proton flux and the helium flux show nearly identical fine structures in both time and relative amplitude. The amplitudes of the flux structures decrease with increasing rigidity and vanish above 40 GV. The amplitudes of the structures are reduced during the time period, which started one year after solar maximum, when the proton and helium fluxes steadily increase. Above ∼3  GV the p/He flux ratio is time independent. We observed that below ∼3  GV the ratio has a long-term decrease coinciding with the period during which the fluxes start to rise.

Observation of New Properties of Secondary Cosmic Rays Lithium, Beryllium, and Boron by the Alpha Magnetic Spectrometer on the International Space Station

We report on the observation of new properties of secondary cosmic rays Li, Be, and B measured in the rigidity (momentum per unit charge) range 1.9 GV to 3.3 TV with a total of 5.4×10^{6} nuclei collected by AMS during the first five years of operation aboard the International Space Station. The Li and B fluxes have an identical rigidity dependence above 7 GV and all three fluxes have an identical rigidity dependence above 30 GV with the Li/Be flux ratio of 2.0±0.1. The three fluxes deviate from a single power law above 200 GV in an identical way. This behavior of secondary cosmic rays has also been observed in the AMS measurement of primary cosmic rays He, C, and O but the rigidity dependences of primary cosmic rays and of secondary cosmic rays are distinctly different. In particular, above 200 GV, the secondary cosmic rays harden more than the primary cosmic rays.

Observation of the Identical Rigidity Dependence of He, C, and O Cosmic Rays at High Rigidities by the Alpha Magnetic Spectrometer on the International Space Station

We report the observation of new properties of primary cosmic rays He, C, and O measured in the rigidity (momentum/charge) range 2 GV to 3 TV with 90×10^{6} helium, 8.4×10^{6} carbon, and 7.0×10^{6} oxygen nuclei collected by the Alpha Magnetic Spectrometer (AMS) during the first five years of operation. Above 60 GV, these three spectra have identical rigidity dependence. They all deviate from a single power law above 200 GV and harden in an identical way.

Precision Measurement of the Boron to Carbon Flux Ratio in Cosmic Rays from 1.9 GV to 2.6 TV with the Alpha Magnetic Spectrometer on the International Space Station

Knowledge of the rigidity dependence of the boron to carbon flux ratio (B/C) is important in understanding the propagation of cosmic rays. The precise measurement of the B/C ratio from 1.9 GV to 2.6 TV, based on 2.3 million boron and 8.3 million carbon nuclei collected by AMS during the first 5 years of operation, is presented. The detailed variation with rigidity of the B/C spectral index is reported for the first time. The B/C ratio does not show any significant structures in contrast to many cosmic ray models that require such structures at high rigidities. Remarkably, above 65 GV, the B/C ratio is well described by a single power law R^{Δ} with index Δ=-0.333±0.014(fit)±0.005(syst), in good agreement with the Kolmogorov theory of turbulence which predicts Δ=-1/3 asymptotically.

Antiproton Flux, Antiproton-to-Proton Flux Ratio, and Properties of Elementary Particle Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station

A precision measurement by AMS of the antiproton flux and the antiproton-to-proton flux ratio in primary cosmic rays in the absolute rigidity range from 1 to 450 GV is presented based on 3.49×10^{5} antiproton events and 2.42×10^{9} proton events. The fluxes and flux ratios of charged elementary particles in cosmic rays are also presented. In the absolute rigidity range ∼60 to ∼500  GV, the antiproton p[over ¯], proton p, and positron e^{+} fluxes are found to have nearly identical rigidity dependence and the electron e^{-} flux exhibits a different rigidity dependence. Below 60 GV, the (p[over ¯]/p), (p[over ¯]/e^{+}), and (p/e^{+}) flux ratios each reaches a maximum. From ∼60 to ∼500  GV, the (p[over ¯]/p), (p[over ¯]/e^{+}), and (p/e^{+}) flux ratios show no rigidity dependence. These are new observations of the properties of elementary particles in the cosmos.

Precision Measurement of the Helium Flux in Primary Cosmic Rays of Rigidities 1.9 GV to 3 TV with the Alpha Magnetic Spectrometer on the International Space Station

Knowledge of the precise rigidity dependence of the helium flux is important in understanding the origin, acceleration, and propagation of cosmic rays. A precise measurement of the helium flux in primary cosmic rays with rigidity (momentum/charge) from 1.9 GV to 3 TV based on 50 million events is presented and compared to the proton flux. The detailed variation with rigidity of the helium flux spectral index is presented for the first time. The spectral index progressively hardens at rigidities larger than 100 GV. The rigidity dependence of the helium flux spectral index is similar to that of the proton spectral index though the magnitudes are different. Remarkably, the spectral index of the proton to helium flux ratio increases with rigidity up to 45 GV and then becomes constant; the flux ratio above 45 GV is well described by a single power law.

Precision Measurement of the Proton Flux in Primary Cosmic Rays from Rigidity 1 GV to 1.8 TV with the Alpha Magnetic Spectrometer on the International Space Station

A precise measurement of the proton flux in primary cosmic rays with rigidity (momentum/charge) from 1 GV to 1.8 TV is presented based on 300 million events. Knowledge of the rigidity dependence of the proton flux is important in understanding the origin, acceleration, and propagation of cosmic rays. We present the detailed variation with rigidity of the flux spectral index for the first time. The spectral index progressively hardens at high rigidities.

Precision Measurement of the (e^{+}+e^{-}) Flux in Primary Cosmic Rays from 0.5 GeV to 1 TeV with the Alpha Magnetic Spectrometer on the International Space Station

We present a measurement of the cosmic ray (e^{+}+e^{-}) flux in the range 0.5 GeV to 1 TeV based on the analysis of 10.6 million (e^{+}+e^{-}) events collected by AMS. The statistics and the resolution of AMS provide a precision measurement of the flux. The flux is smooth and reveals new and distinct information. Above 30.2 GeV, the flux can be described by a single power law with a spectral index γ=-3.170±0.008(stat+syst)±0.008(energy scale).

Electron and positron fluxes in primary cosmic rays measured with the alpha magnetic spectrometer on the international space station

Precision measurements by the Alpha Magnetic Spectrometer on the International Space Station of the primary cosmic-ray electron flux in the range 0.5 to 700 GeV and the positron flux in the range 0.5 to 500 GeV are presented. The electron flux and the positron flux each require a description beyond a single power-law spectrum. Both the electron flux and the positron flux change their behavior at ∼30  GeV but the fluxes are significantly different in their magnitude and energy dependence. Between 20 and 200 GeV the positron spectral index is significantly harder than the electron spectral index. The determination of the differing behavior of the spectral indices versus energy is a new observation and provides important information on the origins of cosmic-ray electrons and positrons.

High statistics measurement of the positron fraction in primary cosmic rays of 0.5-500 GeV with the alpha magnetic spectrometer on the international space station

A precision measurement by AMS of the positron fraction in primary cosmic rays in the energy range from 0.5 to 500 GeV based on 10.9 million positron and electron events is presented. This measurement extends the energy range of our previous observation and increases its precision. The new results show, for the first time, that above ∼200  GeV the positron fraction no longer exhibits an increase with energy.

Electrophysiological and metabolic effects of CHF5074 in the hippocampus: protection against in vitro ischemia

CHF5074 is a non-steroidal anti-inflammatory derivative holding disease-modifying potential for the treatment of Alzheimer's disease. The aim of the present study was to characterize the electrophysiological and metabolic profile of CHF5074 in the hippocampus. Electrophysiological recordings show that CHF5074 inhibits in a dose-dependent manner the current-evoked repetitive firing discharge in CA1 pyramidal neurons. This result is paralleled by a dose-dependent reduction of field excitatory post-synaptic potentials with no effect on the paired-pulse ratio. The effects of CHF5074 were not mediated by AMPA or NMDA receptors, since the inward currents induced by local applications of AMPA and NMDA remained constant in the presence of this compound. We also suggest a possible activity of CHF5074 on ASIC1a receptor since ASIC1a-mediated current, evoked by application of a pH 5.5 solution, is reduced by pretreatment with this compound. Moreover, we demonstrate that CHF5074 treatment is able to counteract in hippocampal slices the OGD-induced increase in alanine, lactate and acetate levels. Finally, CHF5074 significantly reduced the apoptosis in hippocampal neurons exposed to OGD, as revealed by cleaved-caspase-3 immunoreactivity and TUNEL staining. Overall, the present work identifies novel mechanisms for CHF5074 in reducing metabolic acidosis, rendering this compound potentially useful also in conditions of brain ischemia.

First result from the Alpha Magnetic Spectrometer on the International Space Station: precision measurement of the positron fraction in primary cosmic rays of 0.5-350 GeV

A precision measurement by the Alpha Magnetic Spectrometer on the International Space Station of the positron fraction in primary cosmic rays in the energy range from 0.5 to 350 GeV based on 6.8 × 10(6) positron and electron events is presented. The very accurate data show that the positron fraction is steadily increasing from 10 to ∼ 250  GeV, but, from 20 to 250 GeV, the slope decreases by an order of magnitude. The positron fraction spectrum shows no fine structure, and the positron to electron ratio shows no observable anisotropy. Together, these features show the existence of new physical phenomena.

Pharmacological modulation of long-term potentiation in animal models of Alzheimer'’s disease

The discovery of long-term potentiation (LTP) of hippocampal synaptic transmission, which represents a classical model for learning and memory at the cellular level, has stimulated over the past years substantial progress in the understanding of pathogenic mechanisms underlying cognitive disorders, such as Alzheimer’s disease (AD). Multiple lines of evidence indicate synaptic dysfunction not only as a core feature but also a leading cause of AD. Multiple pathways may play a significant role in the execution of synaptic dysfunction and neuronal death triggered by beta-amyloid (Abeta) in AD. Following intensive investigations into LTP in AD models, a variety of compounds have been found to rescue LTP impairment via numerous molecular mechanisms. Yet very few of these findings have been successfully translated into disease-modifying compounds in humans. This review recapitulates the emerging disease-modifying strategies utilized to modulate hippocampal synaptic plasticity with particular attention to approaches targeting ligand-gated ion channels, G-protein-coupled receptors (GPCRs), Receptor Tyrosine Kinases (RTKs) and epigenetic mechanisms. It is hoped that novel multi-targeted drugs capable of regulating spine plasticity might be effective to counteract the progression of AD and related cognitive syndromes.

An electronic learning course on avian influenza in Italy (2008)

The success of emergency intervention to control contagious animal diseases is dependent on the preparedness of veterinary services. In the framework of avian influenza preparedness, the Italian Ministry of Health, in cooperation with the National Reference Centers for Epidemiology and Avian Influenza, implemented an electronic learning course using new web-based information and communication technologies. The course was designed to train veterinary officers involved in disease outbreak management, laboratory diagnosis, and policy making. The "blended learning model" was applied, involving participants in tutor-supported self-learning, collaborative learning activities, and virtual classes. The course duration was 16 hr spread over a 4-wk period. Six editions were implemented for 705 participants. All participants completed the evaluation assignments, and the drop out rate was very low (only 4%). This project increased the number of professionals receiving high-quality training on AI in Italy, while reducing expenditure and maximizing return on effort.

Carpal tunnel syndrome and ulnar neuropathy at the elbow in floor cleaners

OBJECTIVE

To determine the occurrence of carpal tunnel syndrome (CTS) and ulnar neuropathy at the elbow (UNE) in a cohort of floor cleaners and to check differences between workers with and without CTS.

METHODS

All female floor cleaners of three major hospitals in Tuscany (Italy) were contacted. Clinical and electrophysiological severity of CTS and UNE were evaluated with standardized scales and symptoms were assessed with the self-administered Boston Questionnaire (BQ); demographic and non-occupational factors and durations of current and previous occupations were recorded. Univariate analysis of risk factors was performed in workers with and without CTS. Logistic regression was used to evaluate the capacity of independent variables to predict CTS.

RESULTS

Out of a total of 179 cleaners, 145 (81%)-mean age 39.6 years (20-64 years)-were enrolled in the study; 70 (48%) had CTS (diagnosis based on clinical and electrophysiological findings). BQ symptom and hand function scores were anomalous in 108 (74%) and 84 (58%) subjects, respectively. UNE was detected in 7/103 women. Univariate analysis showed that cleaners with CTS were older, had greater BMI and longer exposure to cleaning with previous employers than those without CTS. In the logistic regression, the only predictor of CTS was cleaning with previous employers (O.R. 12.1, 95% CI 3-49.9).

CONCLUSIONS

These results indicate a high occurrence of CTS in floor cleaners; UNE is less frequent than CTS, presumably due to repetitive movements that stress wrists more than elbows. The only predictive factor of CTS was cleaning as an occupation with previous employers. Therefore, the actual risk factor for CTS could not be cleaning per se, but how this job is performed.

Structural and kinetic effects on a simple catalytic reaction: Oxygen reduction on Ni(110)

Oxygen hydrogenation at 100 K by gas phase atomic hydrogen on Ni(110) has been studied under ultrahigh vacuum conditions by temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS). Formation of adsorbed water and hydroxyl species was observed and characterized. The coverage of the reaction products was monitored as a function of both temperature and initial oxygen precoverage. On the contrary, when high coverage oxygen overlayers were exposed to gas phase molecular hydrogen, no hydrogenation reaction took place. The results are compared to the inverse process, exposing the hydrogen covered surface to molecular oxygen. In this case, at 100 K, simple Langmuir-Hinshelwood modeling yields an initial sticking coefficient for oxygen adsorption equal to 0.26, considerably lower than for the clean surface. Moreover, formation of hydroxyl groups is found to be twice as fast as the final hydrogenation of OH groups to water. Assuming a preexponential factor of 10(13) s(-1), an activation barrier of 6.7 kcal/mol is obtained for OH formation, thus confirming the high hydrogenating activity of nickel with respect to other transition metals, for which higher activation energies are reported. However, oxygen is hardly removed by hydrogen on nickel: this is explained on the basis of the strong Ni-O chemical bond. The hydrogen residual coverage is well described including a contribution from the adsorption-induced H desorption process which takes place during the oxygen uptake and which is clearly visible from the TPD data.

Amino-terminal propeptide of type III procollagen is associated with restrictive mitral filling pattern in patients with dilated cardiomyopathy: a possible link between diastolic dysfunction and prognosis

OBJECTIVE

To analyse the relation between restrictive mitral pattern, amino-terminal propeptide of type III procollagen (PIIINP), and prognosis in patients with dilated cardiomyopathy.

DESIGN

Prospective cohort study of 106 patients with dilated cardiomyopathy.

SETTING

Tertiary care centre.

MAIN OUTCOME MEASURES

PIIINP concentration, echocardiographic variables, oxygen consumption, hospitalisation for heart failure, and cardiac mortality were evaluated in patients grouped by the presence of non-restrictive (group 1), reversible (group 2), and irreversible restrictive mitral pattern (group 3).

RESULTS

Groups differed regarding left ventricular ejection fraction (group 1, mean (SD) 36 (6)%, group 2, 29 (8)%, group 3, 25 (6)%; p = 0.0001), left atrial ejection fraction (group 1, 0.47 (0.1)%, group 2, 0.43 (0.2)%, group 3, 0.26 (0.1)%; p < 0.0001), and PIIINP (p = 0.001). Multivariate analysis showed that PIIINP was related to mitral pattern (odds ratio 0.8, 95% confidence interval 0.23 to 1.4, p = 0.006) independently of left atrial and ventricular ejection fractions. After 21 months, survival was 88% and 34% (p = 0.0001) in patients with non-restrictive and irreversible restrictive mitral patterns, respectively.

CONCLUSION

In patients with dilated cardiomyopathy, restrictive mitral pattern is associated with higher PIIINP and worse prognosis.

Cocaine toxic effect on endothelium-dependent vasorelaxation: an in vitro study on rabbit aorta

Effects of cocaine on vascular endothelium relaxing properties and the related mechanism were investigated in vitro in rabbit aorta. Several vasorelaxing agents with different mechanisms, i.e. acetylcholine, substance P, calcium ionophore A23187, 2,5-di-tert-butylhydroquinone, or sodium nitroprusside, were employed. Cocaine effects on the vascular response to relaxing agents in cumulative (acetylcholine, substance P, or A23187) or single dose (2,5-di-tert-butyl-hydroquinone) were performed in endothelium-intact aortic rings precontracted with phenylephrine. Relaxing activity of cumulative doses of sodium nitroprusside was evaluated in endothelium-denuded aortic rings, in the presence of cocaine. Cocaine significantly reduced endothelium-dependent relaxations induced by acetylcholine, or substance P. By contrast A23187 endothelium-mediated relaxation as well as endothelium-independent relaxation by sodium nitroprusside were unaffected by cocaine. Furthermore, cocaine significantly increased endothelium-dependent relaxation response to 2,5-di-tert-butylhydroquinone, a sarcoplasmic Ca2+-ATPase pump inhibitor, in the aortic rings. These findings indicate that cocaine reduces nitric oxide release from vascular endothelium apparently through the inhibiting action of Ca2+-ATPase pump.

Failure of aldosterone suppression despite angiotensin-converting enzyme (ACE) inhibitor administration in chronic heart failure is associated with ACE DD genotype

OBJECTIVES

The objective of this study was to assess whether the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism influences the adequacy of the neurohormonal response to ACE inhibitors in patients with chronic heart failure (CHF).

BACKGROUND

The renin-angiotensin-aldosterone system (RAAS) plays an important role in the pathophysiology of CHF, and aldosterone levels closely relate to outcome in patients with CHF. Angiotensin-converting enzyme inhibitors suppress the RAAS, but a significant proportion of patients exhibit elevated serum levels of aldosterone despite long-term administration of apparently adequate doses of these agents.

METHODS

We prospectively studied 132 patients with CHF (ejection fraction <45%) receiving long-term therapy with ACE inhibitors for over six months. Patients taking aldosterone antagonists were excluded from the study. "Aldosterone escape" was defined as being present when plasma aldosterone levels were above the normal range in our laboratory (>42 nmol/L). Patients were then divided into two subgroups according to the presence (group 1) or absence (group 2) of aldosterone escape. Genotype analysis for the ACE I/D polymorphism was performed by polymerase chain reaction.

RESULTS

The prevalence of aldosterone escape in our patients was 10% (13/132). The two groups of patients did not differ regarding the dose of ACE inhibitor, diuretics and their renal function. There was a statistically significant different distribution of genotypes between the two groups, with a higher proportion of DD genotype in group 1 compared with group 2 (62% vs. 24%, p = 0.005).

CONCLUSIONS

Patients with CHF with aldosterone escape have a higher prevalence of DD genotype compared with patients with aldosterone within the normal limits. Angiotensin-converting enzyme gene polymorphism contributes to the modulation and adequacy of the neurohormonal response to long-term ACE-inhibitor administration in CHF.