Evidence for Astrophysical Muon Neutrinos from the Northern Sky with IceCube

Results from the IceCube Neutrino Observatory have recently provided compelling evidence for the existence of a high energy astrophysical neutrino flux utilizing a dominantly Southern Hemisphere data set consisting primarily of ν(e) and ν(τ) charged-current and neutral-current (cascade) neutrino interactions. In the analysis presented here, a data sample of approximately 35,000 muon neutrinos from the Northern sky is extracted from data taken during 659.5 days of live time recorded between May 2010 and May 2012. While this sample is composed primarily of neutrinos produced by cosmic ray interactions in Earth's atmosphere, the highest energy events are inconsistent with a hypothesis of solely terrestrial origin at 3.7σ significance. These neutrinos can, however, be explained by an astrophysical flux per neutrino flavor at a level of Φ(E(ν))=9.9(-3.4)(+3.9)×10(-19)  GeV(-1) cm(-2) sr(-1) s(-1)(E(ν)/100  TeV(-2), consistent with IceCube's Southern-Hemisphere-dominated result. Additionally, a fit for an astrophysical flux with an arbitrary spectral index is performed. We find a spectral index of 2.2(-0.2)(+0.2), which is also in good agreement with the Southern Hemisphere result.

Flavor Ratio of Astrophysical Neutrinos above 35 TeV in IceCube

A diffuse flux of astrophysical neutrinos above 100 TeV has been observed at the IceCube Neutrino Observatory. Here we extend this analysis to probe the astrophysical flux down to 35 TeV and analyze its flavor composition by classifying events as showers or tracks. Taking advantage of lower atmospheric backgrounds for showerlike events, we obtain a shower-biased sample containing 129 showers and 8 tracks collected in three years from 2010 to 2013. We demonstrate consistency with the (fe:fμ:fτ)⊕≈(1:1:1)⊕ flavor ratio at Earth commonly expected from the averaged oscillations of neutrinos produced by pion decay in distant astrophysical sources. Limits are placed on nonstandard flavor compositions that cannot be produced by averaged neutrino oscillations but could arise in exotic physics scenarios. A maximally tracklike composition of (0:1:0)⊕ is excluded at 3.3σ, and a purely showerlike composition of (1:0:0)⊕ is excluded at 2.3σ.

Development of a general analysis and unfolding scheme and its application to measure the energy spectrum of atmospheric neutrinos with IceCube: IceCube Collaboration

We present the development and application of a generic analysis scheme for the measurement of neutrino spectra with the IceCube detector. This scheme is based on regularized unfolding, preceded by an event selection which uses a Minimum Redundancy Maximum Relevance algorithm to select the relevant variables and a random forest for the classification of events. The analysis has been developed using IceCube data from the 59-string configuration of the detector. 27,771 neutrino candidates were detected in 346 days of livetime. A rejection of 99.9999 % of the atmospheric muon background is achieved. The energy spectrum of the atmospheric neutrino flux is obtained using the TRUEE unfolding program. The unfolded spectrum of atmospheric muon neutrinos covers an energy range from 100 GeV to 1 PeV. Compared to the previous measurement using the detector in the 40-string configuration, the analysis presented here, extends the upper end of the atmospheric neutrino spectrum by more than a factor of two, reaching an energy region that has not been previously accessed by spectral measurements.

Observation of high-energy astrophysical neutrinos in three years of IceCube data

A search for high-energy neutrinos interacting within the IceCube detector between 2010 and 2012 provided the first evidence for a high-energy neutrino flux of extraterrestrial origin. Results from an analysis using the same methods with a third year (2012-2013) of data from the complete IceCube detector are consistent with the previously reported astrophysical flux in the 100 TeV-PeV range at the level of 10(-8)  GeV cm-2 s-1 sr-1 per flavor and reject a purely atmospheric explanation for the combined three-year data at 5.7σ. The data are consistent with expectations for equal fluxes of all three neutrino flavors and with isotropic arrival directions, suggesting either numerous or spatially extended sources. The three-year data set, with a live time of 988 days, contains a total of 37 neutrino candidate events with deposited energies ranging from 30 to 2000 TeV. The 2000-TeV event is the highest-energy neutrino interaction ever observed.

Evidence for high-energy extraterrestrial neutrinos at the IceCube detector

We report on results of an all-sky search for high-energy neutrino events interacting within the IceCube neutrino detector conducted between May 2010 and May 2012. The search follows up on the previous detection of two PeV neutrino events, with improved sensitivity and extended energy coverage down to about 30 TeV. Twenty-six additional events were observed, substantially more than expected from atmospheric backgrounds. Combined, both searches reject a purely atmospheric origin for the 28 events at the 4σ level. These 28 events, which include the highest energy neutrinos ever observed, have flavors, directions, and energies inconsistent with those expected from the atmospheric muon and neutrino backgrounds. These properties are, however, consistent with generic predictions for an additional component of extraterrestrial origin.

Measurement of atmospheric neutrino oscillations with IceCube

We present the first statistically significant detection of neutrino oscillations in the high-energy regime (>20 GeV) from an analysis of IceCube Neutrino Observatory data collected in 2010 and 2011. This measurement is made possible by the low-energy threshold of the DeepCore detector (~20 GeV) and benefits from the use of the IceCube detector as a veto against cosmic-ray-induced muon background. The oscillation signal was detected within a low-energy muon neutrino sample (20-100 GeV) extracted from data collected by DeepCore. A high-energy muon neutrino sample (100 GeV-10 TeV) was extracted from IceCube data to constrain systematic uncertainties. The disappearance of low-energy upward-going muon neutrinos was observed, and the nonoscillation hypothesis is rejected with more than 5σ significance. In a two-neutrino flavor formalism, our data are best described by the atmospheric neutrino oscillation parameters |Δm(32)(2)|=(2.3(-0.5)(+0.6))×10(-3) eV(2) and sin(2)(2θ(23))>0.93, and maximum mixing is favored.

First observation of PeV-energy neutrinos with IceCube

We report on the observation of two neutrino-induced events which have an estimated deposited energy in the IceCube detector of 1.04±0.16 and 1.14±0.17 PeV, respectively, the highest neutrino energies observed so far. These events are consistent with fully contained particle showers induced by neutral-current ν(e,μ,τ) (ν(e,μ,τ)) or charged-current ν(e) (ν(e)) interactions within the IceCube detector. The events were discovered in a search for ultrahigh energy neutrinos using data corresponding to 615.9 days effective live time. The expected number of atmospheric background is 0.082±0.004(stat)(-0.057)(+0.041)(syst). The probability of observing two or more candidate events under the atmospheric background-only hypothesis is 2.9×10(-3) (2.8σ) taking into account the uncertainty on the expected number of background events. These two events could be a first indication of an astrophysical neutrino flux; the moderate significance, however, does not permit a definitive conclusion at this time.

Measurement of the atmospheric νe flux in IceCube

We report the first measurement of the atmospheric electron neutrino flux in the energy range between approximately 80 GeV and 6 TeV, using data recorded during the first year of operation of IceCube's DeepCore low-energy extension. Techniques to identify neutrinos interacting within the DeepCore volume and veto muons originating outside the detector are demonstrated. A sample of 1029 events is observed in 281 days of data, of which 496±66(stat)±88(syst) are estimated to be cascade events, including both electron neutrino and neutral current events. The rest of the sample includes residual backgrounds due to atmospheric muons and charged current interactions of atmospheric muon neutrinos. The flux of the atmospheric electron neutrinos is consistent with models of atmospheric neutrinos in this energy range. This constitutes the first observation of electron neutrinos and neutral current interactions in a very large volume neutrino telescope optimized for the TeV energy range.

Search for dark matter annihilations in the sun with the 79-string IceCube detector

We have performed a search for muon neutrinos from dark matter annihilation in the center of the Sun with the 79-string configuration of the IceCube neutrino telescope. For the first time, the DeepCore subarray is included in the analysis, lowering the energy threshold and extending the search to the austral summer. The 317 days of data collected between June 2010 and May 2011 are consistent with the expected background from atmospheric muons and neutrinos. Upper limits are set on the dark matter annihilation rate, with conversions to limits on spin-dependent and spin-independent scattering cross sections of weakly interacting massive particles (WIMPs) on protons, for WIMP masses in the range 20-5000  GeV/c2. These are the most stringent spin-dependent WIMP-proton cross section limits to date above 35  GeV/c2 for most WIMP models.

Limits on neutrino emission from gamma-ray bursts with the 40 string IceCube detector

IceCube has become the first neutrino telescope with a sensitivity below the TeV neutrino flux predicted from gamma-ray bursts if gamma-ray bursts are responsible for the observed cosmic-ray flux above 10(18)  eV. Two separate analyses using the half-complete IceCube detector, one a dedicated search for neutrinos from pγ interactions in the prompt phase of the gamma-ray burst fireball and the other a generic search for any neutrino emission from these sources over a wide range of energies and emission times, produced no evidence for neutrino emission, excluding prevailing models at 90% confidence.

Extending the search for neutrino point sources with IceCube above the horizon

Point source searches with the IceCube neutrino telescope have been restricted to one hemisphere, due to the exclusive selection of upward going events as a way of rejecting the atmospheric muon background. We show that the region above the horizon can be included by suppressing the background through energy-sensitive cuts. This improves the sensitivity above PeV energies, previously not accessible for declinations of more than a few degrees below the horizon due to the absorption of neutrinos in Earth. We present results based on data collected with 22 strings of IceCube, extending its field of view and energy reach for point source searches. No significant excess above the atmospheric background is observed in a sky scan and in tests of source candidates. Upper limits are reported, which for the first time cover point sources in the southern sky up to EeV energies.

The giant extracellular matrix-binding protein of Staphylococcus epidermidis mediates biofilm accumulation and attachment to fibronectin

Virulence of nosocomial pathogen Staphylococcus epidermidis is essentially related to formation of adherent biofilms, assembled by bacterial attachment to an artificial surface and subsequent production of a matrix that mediates interbacterial adhesion. Growing evidence supports the idea that proteins are functionally involved in S. epidermidis biofilm accumulation. We found that in S. epidermidis 1585v overexpression of a 460 kDa truncated isoform of the extracellular matrix-binding protein (Embp) is necessary for biofilm formation. Embp is a giant fibronectin-binding protein harbouring 59 Found In Various Architectures (FIVAR) and 38 protein G-related albumin-binding (GA) domains. Studies using defined Embp-positive and -negative S. epidermidis strains proved that Embp is sufficient and necessary for biofilm formation. Further data showed that the FIVAR domains of Embp mediate binding of S. epidermidis to solid-phase attached fibronectin, constituting the first step of biofilm formation on conditioned surfaces. The binding site in fibronectin was assigned to the fibronectin domain type III12. Embp-mediated biofilm formation also protected S. epidermidis from phagocytosis by macrophages. Thus, Embp is a multifunctional cell surface protein that mediates attachment to host extracellular matrix, biofilm accumulation and escape from phagocytosis, and therefore is well suited for promoting implant-associated infections.

Incidence and tumour stages of breast cancer in the region of Aachen, Germany

We present epidemiological data of female breast cancer in the region of Aachen (Germany) including incidence and tumour stages for the period 1996-1997. Furthermore, we compare epidemiological data from Aachen with data from the directly neighbouring Dutch region South-Middle Limburg before and after the introduction of a national mammographic screening programme. The field study of breast cancer was undertaken at the Institute of Pathology and Comprehensive Cancer Center at the University of Aachen, supported by the Federal Ministry of Health (Germany), using data files from the Cancer Registry Aachen. The patient's consent to collect all data concerning her epidemiological and social situation as well as information on the outcome of disease was obtained in 83.4% of all cases. The remaining 16.6% of the cases without a patient's consent are based on histopathological reports. Only those patients are included who were documented as residing in the region of Aachen at the time of diagnosis. Tumour cases were counted according to International Agency for Research on Cancer rules and tumour stages are classified according to UICC guidelines. Incidence rates are calculated as crude value, adapted to the European and World Standard population (ESR, WSR), and the age specific incidence is presented in 5-year intervals. The cumulative risk is assessed for a certain life span by summarizing the age-specific incidences. The age-standardized breast cancer incidence rate in Aachen was 94 per 100 000 women in 1996 and 90 cases of invasive breast cancer per 100 000 women in 1997 according to the ESR. The cumulative risk of developing breast cancer in the life span ranging from 0 to 74 years is approximately 8%. The stage distribution of breast cancer reveals only 4% favourable carcinomata in situ, but 12% advanced T4 tumours. T1 and T2 tumour stages count for about 40% and T3 tumour stages about 4%. Incidence rates and the tumour stages of breast cancer in the region of Aachen during 1996 and 1997 are similar to the data obtained from the directly neighbouring Cancer Center of the region South-Middle Limburg, in the Netherlands, in 1989/1990 before the beginning of the national breast cancer screening programme. However, major differences are found in terms of the incidence and the tumour stages between Aachen 1996/1997 and South-Middle Limburg 1995/1996 after the introduction of the mammographic screening. The incidence of female breast cancer in Aachen, Germany, was high and in the range of the data from other cancer registries in Europe without national screening programmes. The tumour stages at diagnosis in Aachen were not very favourable, especially in elderly women. An increase of the cancer incidence and a shift of the tumour stages to more favourable ones were observed in the neighbouring Dutch region of South-Middle Limburg, comparing data from 1989/90 and 1995/96. This is probably as a result of the national mammographic screening programme. As data from Aachen were similar to Limburg's data from 1989/90 before the mammographic screening was introduced, it will be important to follow and compare the cancer incidence and the tumour stages in the future.

The "Silent Springs" of Rachel Carson: mass media and the origins of modern environmentalism

This essay explores the different meanings of the 1960s' pesticide controversy as conveyed by the multiple representations of Rachel Carsons's Silent Spring (1962). I argue that to understand the impact of Carson's work on a heterogeneous audience in the early '60s, we must move beyond an examination of the book, Silent Spring, to consider its other media manifestations, as a serialization for The New Yorker and as a television exposé for "CBS Reports." Each conveyed a unique message stylized for the audience of that particular media. This analysis demonstrates the problems and opportunities for scholars attempting to gauge the influence of a book on the public understanding of science. This argument also suggests that to understand the transition of environmentalism from a grass-roots movement to near universal consensus, we need to examine carefully the role of media in shaping divergent messages for different audiences--a phenomenon that assisted in transforming local environmental issues into a matter of national concern.

Case report. Pathohistological findings in a clinical case of disseminated infection with Fusarium oxysporum

Despite appropriate antimicrobial and antifungal therapy (amphotericin B), a disseminated infection with Fusarium oxysporum in a 75-year-old immunocompromised patient (acute myeloid leukaemia, minimal leucocyte count of 0.5 giga l-1) led rapidly to death. A similarly fatal course of an F. oxysporum infection has been reported in several cases. Fusarium oxysporum could be isolated shortly before death from blood cultures and from a swab taken from skin efflorescences. An autopsy revealed histopathologically typical fungal infiltrates in the mucosa of the pharynx, epiglottis, trachea, and oesophagus and in the parenchyma of the spleen, the lung and both kidneys. Because of the high risk of a fatal outcome of this infection, the clinician should aim at maximum diagnostic enforcement. We propose both analysis of blood cultures and immediate skin biopsy--with PAS-staining--of suspicious dermal efflorescences for microscopic examination. The treatment of choice is discussed controversially but a beneficial effect has been reported from granulocyte transfusion, subcutaneous administration of GM-CSF and concomitant treatment with amphotericin B.

Lipoma of the corpus callosum

A case of corpus callosum lipoma with presumptive diagnosis is presented. Review of the literature disclosed 84 cases with such diagnoses. Lipoma of the corpus callosum is a rare intracranial lesion, perhaps congenital and often asymptomatic, but can present with seizure disorder, headache, mental changes, paresis or paralysis. Twenty-one patients had been operated upon. Surgical treatment seems to be of no value in this disease.

Massive left atrial thrombus: a case report

This case report describes a patient with aortic and mitral valvular disease who had a massive left atrial thrombus. The left atrial thrombus produced a disappearance of signs of mitral stenosis and a reversed pan diastolic mitral valve gradient. This gradient occurred in the absence of any diastolic mitral insufficiency and may have been due to artifactual lowering of the left atrial pressure by an organized left atrial clot.