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.

Prognosis of arterial aneurysm after surgery in patients with Behçet's disease

AIM

Despite improvements in therapeutic modalities, the treatment of arterial aneurysms complicating Behçet's disease (BD) is still challenging. This study examined the long-term prognosis after surgery for arterial aneurysms in BD.

METHODS

This study included 9 patients with BD (8 men and 1 woman) who underwent surgery for arterial aneurysms between 1989 and 2008. The outcomes after the surgical intervention were assessed, including procedure-related complications and survival.

RESULTS

The initial surgical procedures were performed for aortic or iliac aneurysms in 5 patients and for lower-extremity aneurysms in 4 patients. There was no operative mortality. The mean follow-up period was 135±69 months, ranging from 53 to 259 months. Patients with aortic or iliac aneurysms underwent graft interposition with Dacron prostheses. Their postoperative courses were uneventful, and all patients were alive during the follow-up with no procedure-related complications. Those treated for lower-extremity aneurysms tended to show perioperative and postoperative complications, including aneurysmal degeneration of the autogenous vein graft in 2 patients. One patient who initially underwent surgery for a popliteal artery aneurysm died due to the rupture of a dissecting aortic aneurysm after serial surgical interventions for multiple aneurysms. Concomitant aortic or iliac aneurysms in 2 patients were followed up without any change in size under medical treatment using colchicine and corticosteroids.

CONCLUSION

Although we cannot draw a firm conclusion because of the small number of cases in the present series, graft interposition can lead to a favorable prognosis in BD patients with aortic or iliac aneurysms, whereas surgical treatment of BD-related lower-extremity aneurysms is frequently associated with short- and long-term postoperative complications. Immunosuppressive therapy might possibly improve treatment outcomes.

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.

Fate of the asymptomatic contralateral limb after initial intervention for ipsilateral critical limb ischemia

AIM

In Trans-Atlantic Inter-Society Concensus (TASC) II, patients at risk for critical limb ischemia (CLI) without symptoms are termed "chronic subclinical ische mia," but research are still lacking. The objective was to find out whether clinically asymptomatic contralateral limbs at the time of treatment for ipsilateral CLI could be regarded as "chronic subclinical ischemia".

METHODS

Ninety-six patients with CLI who had no symptoms in the contralateral limb were retrospectively reviewed. The symptoms of the contralateral limb after initial intervention for the ipsilateral limb were surveyed. Risk factors for developing CLI and tissue loss were then analyzed.

RESULTS

Five patients (5.2%) became claudicants, 37 patients (38.5%) had symptoms of CLI, and 14 (14.6%) experienced tissue loss during the follow-up period. The overall CLI-free rates at 12, 36, and 60 months were 79.2%, 55.2%, and 45.8%, respectively, while the tissue loss-free rates at 12, 36, and 60 months were 91.3%, 78.8%, and 78.8%, respectively. Risk factor for developing CLI on the contralateral limb was having skin perfusion pressure (SPP) <40 mmHg at the surgery for ipsilateral limb. The presence of SPP <40 mmHg and end stage renal failure with hemodialysis resulted in a significantly high probability of tissue loss.

CONCLUSION

Patients with CLI with an asymptomatic contralateral limb with an SPP value <40 mmHg are at a high risk of developing CLI and tissue loss during the follow-up period. Information on the contralateral limb at initial surgery may help to speculate the fate of the asymptomatic contralateral limb.

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.

Electronic spectroscopy of the HCCN radical

The Ã(3)A"-X̃(3)Σ(-) electronic transition of the HCCN∕DCCN radical was observed by laser-induced fluorescence spectroscopy. Rotationally resolved excitation spectra were observed for HCCN and DCCN, and effective molecular constants of the upper state were determined. The observed intensities of the rotational lines were anomalous, probably due to a level-dependent non-radiative decay process in the excited state. Fluorescence depletion spectroscopy was applied in order to observe non-fluorescent vibronic levels. A dispersed fluorescence spectrum was also observed to determine the vibrational level structure in the ground electronic state. The observed vibrational structures in the fluorescence depletion and dispersed fluorescence spectra were tentatively assigned based on the results of ab initio calculations.

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.

Middle-term results of endovascular aneurysm repair in Japan: does intraoperative endovascular management against the hostile aneurysmal neck prevent the proximal type I endoleak?

AIM

Endovascular aneurysm repair (EVAR) was first approved in Japan in 2007. In order to avoid the learning curve generally seen in the initial stages of implementation, we have aimed for procedural perfection. As the proximal type I endoleak (EL) is associated with a higher risk of late conversion and rupture, so we have treated the intraoperative type I EL scrupulously. The hostile neck, which is known to be a risk for perigraft leakage, is the focus of this study. We showed both the middle-term results of EVAR in our country and the possible necessity of intraoperative management for the hostile neck.

METHODS

From a consecutive series of 134 patients who underwent EVAR of abdominal aortic aneurysms, 129 cases in which contrast agent was used intraoperatively were selected. All cases had at least 12-month follow-up postoperatively (12-40 months). Of the 129 selected cases, 49 cases (37%) that did not fulfill the commercially recommended criteria of the aneurysmal neck (length <15 mm and angle >60° of the aneurysm or >45° of the suprarenal aorta) were assigned to the off-label group. The other 80 cases were assigned to the on-label group. We carefully observed the completion angiography and when we found or suspected a type I EL, we performed a re-touch up, changed to a non-compliant balloon, and used a supportive device, such as a PalmazTM stent or aortic cuffs, in sequence.

RESULTS

No postoperative type I ELs were detected within the follow-up period. Intraoperative type I ELs were detected more frequently in the off-label group (51%) than the on-label group (20%) (P<0.01). The rate of type I EL in the off-label group in terms of the neck length criteria (11/14 cases) was higher than that in the on-label group (30/115 cases) (P<0.01). In terms of the neck angle, patients in the off-label group had a greater tendency to develop the type I EL than those in the on-label group (18/42 vs. 23/87 cases) (P=0.06).

CONCLUSION

Off-label usage regarding aneurysmal neck length and angle tends to be incomplete without additional procedures. Conversely, various techniques, including non-compliant balloon usage and aortic stenting or cuffs, produce good results for the intraoperative type I EL. We found a relationship between the neck condition and the intraoperative type I EL, and showed the importance of strictly obeying our simple algorithm against the proximal type I EL.

Surgical treatment of patients with congenital vascular malformation-associated aneurysms

OBJECTIVES

Aneurysms associated with congenital vascular malformation (CVM) comprise critical complication. We review our experience with extracranial CVM-associated aneurysms and attempt to clarify their clinical features.

PATIENTS AND METHODS

The prevalence, site, size and morphology of the accompanying aneurysms of 48 consecutive CVM patients, who were managed at our hospital from 1999 to 2008, were evaluated. After diagnosis or treatment, the patients were followed up, and the recurrence of aneurysms and patient survival were assessed.

RESULTS

CVM-associated aneurysms were found in 14 patients (29%). CVMs were classified according to the Hamburg classification. The patients were classified into groups as follows: four (31%), in the 'predominantly arteriovenous (AV) shunting defect type'; eight (47%), 'combined vascular defects + predominantly AV shunting defects type'; and two (11%), 'combined vascular defects type'. All aneurysms except one situated at the CVM were saccular, whereas nine were fusiform aneurysms; all the ruptured aneurysms and seven out of the nine enlarging aneurysms were saccular. Surgical treatment was performed 8 times in six patients. During the postoperative follow-up period, recurrence and an aneurysm rupture were encountered in one patient each.

CONCLUSION

Aneurysm is not a rare complication of CVM. It is important to treat CVM before the emergency presents. In addition to the treatment for malformation, regular screening for and proper management of the aneurysms in CVM patients are indispensable.

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.