Fruit encasing preserves the dispersal potential and viability of stranded Posidonia oceanica seeds

Posidonia oceanica meadows are the most productive coastal ecosystem in the Mediterranean. Posidonia oceanica seeds are enclosed in buoyant fleshy fruits that allow dispersal. Many fruits eventually strand on beaches, imposing a remarkable energy cost for the plant. This study aims to assess whether stranded seeds retain functional reproductive potential under a variety of environmental conditions. First, we measured the possibility that seeds could be returned to the sea, by tagging fruits and seeds. Second, we quantified the effect of air, sun and heat exposure on the viability and fitness of stranded fruits and naked seeds. The results showed that on average more than half of fruits and seeds are returned to the sea after stranding events and that fruits significantly protect from desiccation and loss of viability. Furthermore, in fruits exposed to the sun and in naked seeds, seedlings development was slower. This study indicates that a significant portion of stranded P. oceanica fruits have a second chance to recruit and develop into young seedlings, relieving the paradox of large energy investment in seed production and apparent low recruitment rate. Additionally, we provide practical indications for seed collection aimed at maximizing seedling production, useful in meadow restoration campaigns.

Unresolved Gamma-Ray Sky through its Angular Power Spectrum

The gamma-ray sky has been observed with unprecedented accuracy in the last decade by the Fermi -large area telescope (LAT), allowing us to resolve and understand the high-energy Universe. The nature of the remaining unresolved emission [unresolved gamma-ray background (UGRB)] below the LAT source detection threshold can be uncovered by characterizing the amplitude and angular scale of the UGRB fluctuation field. This Letter presents a measurement of the UGRB autocorrelation angular power spectrum based on eight years of Fermi-LAT Pass 8 data products. The analysis is designed to be robust against contamination from resolved sources and noise systematics. The sensitivity to subthreshold sources is greatly enhanced with respect to previous measurements. We find evidence (with ∼3.7σ significance) that the scenario in which two classes of sources contribute to the UGRB signal is favored over a single class. A double power law with exponential cutoff can explain the anisotropy energy spectrum well, with photon indices of the two populations being 2.55±0.23 and 1.86±0.15.

Endoscopic Treatment of Postradiation Strictures

Background

Esophageal stricture is a rare complication of radiotherapy: reports on its incidence and management are therefore anecdotal.

Methods

From January 1978 to September 1992, 44 patients presenting with an esophageal stricture related to a previous radiation treatment were endo-scopically dilated at the Endoscopy Division of the Istituto Nazionale Tumori of Milan.

Results

Esophageal recanalization was obtained in 95 % of the patients treated, and in 79 % of these normal eating habits were restored. No strict correlation was observed between radiation dose and severity of the stricture, or time elapsed between first treatment and endoscopic dilation.

Conclusions

In our experience, endoscopic dilation was a safe effective procedure and represented an effective palliative tool in dysphagic patients with esophageal strictures due to previous local radiotherapy.

Laparoscopy in Staging and Restaging of 95 Patients with Ovarian Carcinoma

The merits of laparoscopy with inspection of diaphragmatic leaves were studied in 95 patients with ovarian carcinoma. Laparoscopy was positive in 19 out of 27 new cases, 11 out of 47 patients previously treated and in apparent complete remission, and 12 out of 21 patients previously treated and with disease. Thirty-one out of 95 patients were shown to have diaphragmatic metastases alone and/or associated with other localizations of disease. In 5 out of 27 new cases the stage was modified after laparoscopy. The histologic-endoscopic correlation was correct in 28/36 positive cases (78 %) and in 31/32 negative cases (97 %). In conclusion, all patients with ovarian carcinoma should be subjected to laparoscopy as staging and restaging before undergoing laparotomy.

Endoscopic Treatment of Carpet-Like Adenomas of the Rectum

Background

Transanal microsurgery, endoscopic laser photocoagulation and snare resection have all been used to treat large sessile adenomas of the rectum alternatively to a surgical approach. However, such modalities are often defective due to the carpet-like shape and the frequently large extension of the lesions.

Methods

Ten patients with carpet-like adenoma were submitted to transanal endoscopic resection by urological resectoscope.

Results

Complete eradication was obtained in all lesions. The mean number of treatment sessions was 3 (range, 1-5). The mean time between the first treatment and the complete eradication was 6 months (range, 1-18). The only complications were an intraoperative and an early postoperative bleeding. There was no early or late mortality related to the procedure.

Conclusions

Transanal endoscopic resection by urological resectoscope appears to be a suitable therapeutic approach for sessile and carpet-like adenomas of the rectum or for pTI cancer in patients who refuse major surgery.

Risk of Colorectal Cancer following Colonoscopic Polypectomy

Aims and Background

To follow a cohort of patients who had undergone polypectomies in order to assess the overall risk of subsequent colorectal cancer in relation with various adenomas characteristics.

Methods

A total of 1,063 patients with adenomatous polyps of the large intestine were treated between 1979 and 1996 at the National Cancer Institute of Milan, during a screening program for colorectal carcinoma. Data on patients who had undergone colonoscopies were collected prospectively. The relation between colorectal cancer and adenomas characteristics was assessed by computing the hazard ratio (HR) values and corresponding confidence intervals (95% CI), according to Cox.

Results

Of the 1,063 patients who met the eligibility requirements, 672 had single adenomas (63.2%) and 391 had multiple adenomas (36.8%). Histological examination revealed 743 cases of tubular adenoma, 196 cases of tubulo-villous adenoma, and 96 cases of villous adenoma. High-grade dysplasia was found in 3.1% of the cases. During the 8,906 persons/year of follow-up, adenocarcinomas of the large bowel developed in 11 patients. Several adenomas’ characteristics at index polypectomy were significant predictors of colorectal cancer occurrence. In univariate analysis the risk of colon cancer was significantly related with multiple adenomas (HR 4.2, 95% CI 1.1-6.5), high-grade dysplasia adenomas (HR 10.0, 95% CI 2.6-38.1) and with adenomas larger than 2 cm (HR 5.0, 95% CI 1.2-20.4). A multivariate stepwise procedure confirmed that the presence of multiple adenomas and presence of high-grade dysplasia are the most important predictors of carcinomas. Hazard ratios for colorectal cancer occurrence, from multivariate Cox's model, were 5.1 (95% CI 1.2-19.9) for multiple compared to single adenomas, and 13.0 (95% CI 3.6-50.7) for adenomas with high-grade dysplasia compared to those with low-grade dysplasia.

Conclusions

High-grade dysplasia, number and size of adenomas were confirmed as the major cancer predictors. Based on this conclusion, a subgroup of patients, who may benefit from intensive surveillance colonoscopy, can be identifiable.

Total Parenteral Nutrition and Tumor Growth in Malnourished Patients with Gastric Cancer

Aims and Background

Evidence that total parenteral nutrition (TPN) can stimulate tumor growth in humans is scanty and contradictory. The purpose of this study was to evaluate the impact of TPN on tumor cell proliferation in malnourished patients receiving preoperative TPN.

Methods

We evaluated variations in the S-phase cell fraction, defined as 3H-thymidine labeling index (TLI), before and after 10 days of TPN or non-administration of nutritional support in 19 malnourished patients (weight loss, ≥ 10%) with gastric cancer. TLI was determined on endoscopic biopsies at the time of diagnosis, and subsequently on the operative specimen or through intraoperative sampling.

Results

At diagnosis, a higher median TLI value was observed in the control than in the TPN group. Administration of TPN enhanced tumor cell proliferation in 50% of patients; however, at surgery there was no difference in the median TLI value of the two groups.

Conclusions

The TPN regimen seems to be associated with increased tumor cell proliferation, even though this stimulating effect was moderate and at surgery the TLIS of TPN patients and controls were not different. Although the potential stimulation probably has little consequence for patients receiving short-term preoperative nutrition, it may call for further investigation in cancer patients undergoing long-term home TPN.

Laser Phototherapy following HpD Administration in Superficial Neoplastic Lesions

We report our preliminary clinical experience with hematoporphyrin derivative (HpD) injection and argon or dye laser irradiation for the treatment of 61 surface neoplastic lesions in 7 patients. Forty-three sites were multiple basal cell carcinoma in 5 patients, and the remaining 18 were cutaneous and subcutaneous recurrent breast carcinoma after mastectomy in the thoracic wall. The patients were selected on the basis of the lack of indication for conventional therapeutic modalities. The selection of irradiation procedures and laser source was based on the thickness of the lesion and extension of the disease. The photochemical reaction between HpD injected i.v. at a dose of 3 mg/kg body weight and the laser beam at a dose of 60 to 120 J/cm2 resulted in 75 % favorable responses at the treated sites. Optimal therapeutic effects appeared to be critically dependent on total light dose and tumor infiltration patterns. The phototherapeutic technique proved to be effective in selected cases of neoplastic lesions, especially when conventional treatment modalities were poorly indicated or contraindicated.

Laparoscopy Combined with Peritoneal Cytology in Staging and Restaging Ovarian Carcinoma

The merits of laparoscopy, with inspection of the diaphragmatic leaves, and of peritoneal cytology (free fluid or washing) in staging and restaging were studied in 153 patients with ovarian carcinoma. Of 153 patients examined, 83 were new cases, 34 were restaging in patients without clinical and/or radiological signs of disease, and 36 in patients with evident disease. The conversion rate for diaphragmatic metastases alone was 6%. Information about the spread of disease (diaphragmatic metastases) was obtained in 33 new cases (39.7%). In pretreated patients, laparoscopy was positive in 4 of 34 NED restaging and in 24 of 36 ED restaging. The conversion rate for peritoneal cytology was 6.6%, but information about the cellular intraperitoneal spread of the disease was obtained in 31 new cases (37.8%). In pretreated patients, peritoneal cytology was positive in 4 of 34 NED restaging and in 13 of 36 ED restaging.

Preoperative Endoscopic Ultrasonography in Patients with Gastric Cancer

Aims and background

There is a need to assess the accuracy of endoscopic ultrasonography (EUS) in the diagnosis and staging of gastric cancer, especially in the early and very advanced stages of the disease when the therapeutic approach is still controversial.

Methods

A retrospective study was performed on 79 patients with gastric cancer in order to compare the stage defined by preoperative EUS with that assessed histopathologically. All patients underwent laparotomy for final diagnosis, staging, and eventually treatment. The results of EUS were correlated with the histologic findings of the resected specimens.

Results

In the uT1 group, which corresponds to early gastric cancer, the diagnosis was histologically confirmed in 85.7% of the cases. In patients with advanced tumors defined as uT3-uT4, i.e., tumors infiltrating the serosa or neighboring structures, the diagnostic concordance was 91.1%. In contrast, concordance for less advanced lesions confined to the muscular layer was only 31.2%. As regards the lymph nodes, they were defined metastatic in 31 patients and confirmed to be histologically involved in 77.4%. In contrast, when the lymph nodes were assessed as negative at EUS, they proved to be metastatic in more than half the cases.

Conclusions

From the data it appears that EUS has proven to be valuable in correctly staging most of the patients. EUS shows not only tumor depth and local spread but also the passage from a pathologic to a normal wall and lymph node metastasis. EUS appears to represent an important advance in the staging and follow-up of patients with gastric cancer. Instruments and techniques will continue to evolve, but the next level of research should be designed to show that the improved staging provided by EUS has clinical utility and can affect patient outcome. It is noteworthy that the highest accuracy of EUS has been shown in those conditions (uT1 and uT3-4) which currently are under consideration for a therapeutic approach that differs from the standard one.

Search for Cosmic-Ray Electron and Positron Anisotropies with Seven Years of Fermi Large Area Telescope Data

The Large Area Telescope on board the Fermi Gamma-ray Space Telescope has collected the largest ever sample of high-energy cosmic-ray electron and positron events since the beginning of its operation. Potential anisotropies in the arrival directions of cosmic-ray electrons or positrons could be a signature of the presence of nearby sources. We use almost seven years of data with energies above 42 GeV processed with the Pass 8 reconstruction. The present data sample can probe dipole anisotropies down to a level of 10^{-3}. We take into account systematic effects that could mimic true anisotropies at this level. We present a detailed study of the event selection optimization of the cosmic-ray electrons and positrons to be used for anisotropy searches. Since no significant anisotropies have been detected on any angular scale, we present upper limits on the dipole anisotropy. The present constraints are among the strongest to date probing the presence of nearby young and middle-aged sources.

Search for Spectral Irregularities due to Photon-Axionlike-Particle Oscillations with the Fermi Large Area Telescope

We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5×10^{-12}  GeV^{-1} for ALP masses 0.5≲m_{a}≲5  neV at 95% confidence. The limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the γ-ray opacity of the Universe.

Resolving the Extragalactic γ-Ray Background above 50 GeV with the Fermi Large Area Telescope

The Fermi Large Area Telescope (LAT) Collaboration has recently released a catalog of 360 sources detected above 50 GeV (2FHL). This catalog was obtained using 80 months of data re-processed with Pass 8, the newest event-level analysis, which significantly improves the acceptance and angular resolution of the instrument. Most of the 2FHL sources at high Galactic latitude are blazars. Using detailed Monte Carlo simulations, we measure, for the first time, the source count distribution, dN/dS, of extragalactic γ-ray sources at E>50  GeV and find that it is compatible with a Euclidean distribution down to the lowest measured source flux in the 2FHL (∼8×10^{-12}  ph cm^{-2} s^{-1}). We employ a one-point photon fluctuation analysis to constrain the behavior of dN/dS below the source detection threshold. Overall, the source count distribution is constrained over three decades in flux and found compatible with a broken power law with a break flux, S_{b}, in the range [8×10^{-12},1.5×10^{-11}]  ph cm^{-2} s^{-1} and power-law indices below and above the break of α_{2}∈[1.60,1.75] and α_{1}=2.49±0.12, respectively. Integration of dN/dS shows that point sources account for at least 86_{-14}^{+16}% of the total extragalactic γ-ray background. The simple form of the derived source count distribution is consistent with a single population (i.e., blazars) dominating the source counts to the minimum flux explored by this analysis. We estimate the density of sources detectable in blind surveys that will be performed in the coming years by the Cherenkov Telescope Array.

Measurement of the high-energy gamma-ray emission from the Moon with the Fermi Large Area Telescope

We have measured the gamma-ray emission spectrum of the Moon using the data collected by the Large Area Telescope onboard the Fermi satellite during its first seven years of operation, in the energy range from 30 MeV up to a few GeV. We have also studied the time evolution of the flux, finding a correlation with the solar activity. We have developed a full Monte Carlo simulation describing the interactions of cosmic rays with the lunar surface. The results of the present analysis can be explained in the framework of this model, where the production of gamma rays is due to the interactions of cosmic-ray proton and helium nuclei with the surface of the Moon. Finally, we have used our simulation to derive the cosmic-ray proton and helium spectra near Earth from the Moon gamma-ray data.

Searching for Dark Matter Annihilation from Milky Way Dwarf Spheroidal Galaxies with Six Years of Fermi Large Area Telescope Data

The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on γ-ray observations of Milky Way dSphs based on six years of Fermi Large Area Telescope data processed with the new Pass8 event-level analysis. None of the dSphs are significantly detected in γ rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. These constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DM of mass ≲100  GeV annihilating via quark and τ-lepton channels.

Inferred cosmic-ray spectrum from Fermi large area telescope γ-ray observations of Earth's limb

Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the γ-ray emission from Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range ∼90  GeV-6  TeV (derived from a photon energy range 15 GeV-1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68±0.04 and 2.61±0.08 above ∼200  GeV, respectively.

Fermi LARGE AREA TELESCOPE OBSERVATIONS OF BLAZAR 3C 279 OCCULTATIONS BY THE SUN

Observations of occultations of bright γ-ray sources by the Sun may reveal predicted pair halos around blazars and/or new physics, such as, e.g., hypothetical light dark matter particles-axions. We use Fermi Gamma-Ray Space Telescope (Fermi) data to analyze four occultations of blazar 3C 279 by the Sun on October 8 each year from 2008 to 2011. A combined analysis of the observations of these occultations allows a point-like source at the position of 3C 279 to be detected with significance of ≈3σ, but does not reveal any significant excess over the flux expected from the quiescent Sun. The likelihood ratio test rules out complete transparency of the Sun to the blazar γ-ray emission at a 3σ confidence level.

Prospects of near-field plasmonic absorption enhancement in semiconductor materials using embedded Ag nanoparticles

Metal nanoparticles are efficient antennas for light. If embedded in a semiconductor material, they can enhance light absorption in the semiconductor, due to the strong plasmonic near-field coupling. We use numerical simulations to calculate the absorption enhancement in the semiconductor using Ag nanoparticles with diameters in the range 5-60 nm for crystalline Si, amorphous Si, a polymer blend, and Fe₂O₃. We study single Ag particles in a 100×100×100 nm semiconductor volume, as well as periodic arrays with 100 nm pitch. We find that in all cases Ohmic dissipation in the metal is a major absorption factor. In crystalline Si, while Ag nanoparticles cause a 5-fold enhancement of the absorbance in the weakly absorbing near-bandgap spectral range, Ohmic losses in the metal dominate the absorption. We conclude crystalline Si cannot be sensitized with Ag nanoparticles in a practical way. Similar results are found for Fe₂O₃. The absorbance in the polymer blend can be enhanced by up to 100% using Ag nanoparticles, at the expense of strong additional absorption by Ohmic losses. Amorphous Si cannot be sensitized with Ag nanoparticles due to the mismatch between the plasmon resonance and the bandgap of a-Si. By using sensitization with Ag nanoparticles the thickness of some semiconductor materials can be reduced while keeping the same absorbance, which has benefits for materials with short carrier diffusion lengths. Scattering mechanisms by plasmonic nanoparticles that are beneficial for enhanced light trapping in solar cells are not considered in this paper.

Broadband omnidirectional antireflection coating based on subwavelength surface Mie resonators

Reflection is a natural phenomenon that occurs when light passes the interface between materials with different refractive index. In many applications, such as solar cells or photodetectors, reflection is an unwanted loss process. Many ways to reduce reflection from a substrate have been investigated so far, including dielectric interference coatings, surface texturing, adiabatic index matching and scattering from plasmonic nanoparticles. Here we present an entirely new concept that suppresses the reflection of light from a silicon surface over a broad spectral range. A two-dimensional periodic array of subwavelength silicon nanocylinders designed to possess strongly substrate-coupled Mie resonances yields almost zero total reflectance over the entire spectral range from the ultraviolet to the near-infrared. This new antireflection concept relies on the strong forward scattering that occurs when a scattering structure is placed in close proximity to a high-index substrate with a high optical density of states.

Minimising reflection from the interface between materials is an important goal for optical devices such as solar cells or photodetectors. Spinelli et al. show almost total loss of reflection over a broad spectral range from a silicon surface using periodic arrays of sub-wavelength silicon nanocylinders.

Measurement of separate cosmic-ray electron and positron spectra with the fermi large area telescope

We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because the instrument does not have an onboard magnet, we distinguish the two species by exploiting Earth's shadow, which is offset in opposite directions for opposite charges due to Earth's magnetic field. We estimate and subtract the cosmic-ray proton background using two different methods that produce consistent results. We report the electron-only spectrum, the positron-only spectrum, and the positron fraction between 20 and 200 GeV. We confirm that the fraction rises with energy in the 20-100 GeV range. The three new spectral points between 100 and 200 GeV are consistent with a fraction that is continuing to rise with energy.

Constraining dark matter models from a combined analysis of Milky Way satellites with the Fermi Large Area Telescope

Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10(-26)  cm3  s(-1) at 5 GeV to about 5×10(-23)   cm3  s(-1) at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section (∼3×10(-26)  cm3  s(-1) for a purely s-wave cross section), without assuming additional boost factors.

Controlling Fano lineshapes in plasmon-mediated light coupling into a substrate

Metal nanoparticles are efficient resonant plasmonic scatterers for light, and, if placed on top of a high-index substrate, can efficiently couple light into the substrate. This coupling, however, strongly depends on particle shape and surrounding environment. We study the effect of particle shape and substrate refractive index on the plasmonic resonances of silver nanoparticles and we systematically relate this to the efficiency of light scattering into a substrate. The light coupling spectra are dominated by Fano resonances for the corresponding dipolar and quadrupolar scattering modes. Varying the particle shape from spherical to cylindrical leads to large shifts in the Fano resonance for the dipolar mode, reducing the light incoupling integrated over the AM1.5 spectral range. Using a dielectric spacer layer, good light coupling is achieved for cylinders in the near-infrared. An asymmetric environment around the particles turns quadrupolar resonances into efficient radiators as well.

Optical impedance matching using coupled plasmonic nanoparticle arrays

Silver nanoparticle arrays placed on top of a high-refractive index substrate enhance the coupling of light into the substrate over a broad spectral range. We perform a systematic numerical and experimental study of the light incoupling by arrays of Ag nanoparticle arrays in order to achieve the best impedance matching between light propagating in air and in the substrate. We identify the parameters that determine the incoupling efficiency, including the effect of Fano resonances in the scattering, interparticle coupling, as well as resonance shifts due to variations in the near-field coupling to the substrate and spacer layer. The optimal configuration studied is a square array of 200 nm wide, 125 nm high spheroidal Ag particles, at a pitch of 450 nm on a 50 nm thick Si(3)N(4) spacer layer on a Si substrate. When integrated over the AM1.5 solar spectral range from 300 to 1100 nm, this particle array shows 50% enhanced incoupling compared to a bare Si wafer, 8% higher than a standard interference antireflection coating. Experimental data show that the enhancement occurs mostly in the spectral range near the Si band gap. This study opens new perspectives for antireflection coating applications in optical devices and for light management in Si solar cells.

Gamma-ray emission concurrent with the nova in the symbiotic binary V407 Cygni

Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from the nova shell can produce x-ray emission, but emission at higher energies has not been widely expected. Here, we report the Fermi Large Area Telescope detection of variable gamma-ray emission (0.1 to 10 billion electron volts) from the recently detected optical nova of the symbiotic star V407 Cygni. We propose that the material of the nova shell interacts with the dense ambient medium of the red giant primary and that particles can be accelerated effectively to produce pi(0) decay gamma-rays from proton-proton interactions. Emission involving inverse Compton scattering of the red giant radiation is also considered and is not ruled out.

Spectrum of the isotropic diffuse gamma-ray emission derived from first-year Fermi Large Area Telescope data

We report on the first Fermi Large Area Telescope (LAT) measurements of the so-called "extragalactic" diffuse gamma-ray emission (EGB). This component of the diffuse gamma-ray emission is generally considered to have an isotropic or nearly isotropic distribution on the sky with diverse contributions discussed in the literature. The derivation of the EGB is based on detailed modeling of the bright foreground diffuse Galactic gamma-ray emission, the detected LAT sources, and the solar gamma-ray emission. We find the spectrum of the EGB is consistent with a power law with a differential spectral index gamma = 2.41 +/- 0.05 and intensity I(>100 MeV) = (1.03 +/- 0.17) x 10(-5) cm(-2) s(-1) sr(-1), where the error is systematics dominated. Our EGB spectrum is featureless, less intense, and softer than that derived from EGRET data.

Fermi large area telescope search for photon lines from 30 to 200 GeV and dark matter implications

Dark matter (DM) particle annihilation or decay can produce monochromatic gamma rays readily distinguishable from astrophysical sources. gamma-ray line limits from 30 to 200 GeV obtained from 11 months of Fermi Large Area Space Telescope data from 20-300 GeV are presented using a selection based on requirements for a gamma-ray line analysis, and integrated over most of the sky. We obtain gamma-ray line flux upper limits in the range 0.6-4.5x10{-9} cm{-2} s{-1}, and give corresponding DM annihilation cross-section and decay lifetime limits. Theoretical implications are briefly discussed.

Fermi large area telescope measurements of the diffuse gamma-ray emission at intermediate galactic latitudes

The diffuse galactic gamma-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess gamma-ray emission greater, > or approximately equal to 1 GeV relative to diffuse galactic gamma-ray emission models consistent with directly measured CR spectra (the so-called "EGRET GeV excess"). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse gamma-ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV and galactic latitudes 10 degrees < or = |b| < or = 20 degrees. The LAT spectrum for this region of the sky is well reproduced by a diffuse galactic gamma-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.

Detection of high-energy gamma-ray emission from the globular cluster 47 Tucanae with Fermi

We report the detection of gamma-ray emissions above 200 megaelectron volts at a significance level of 17sigma from the globular cluster 47 Tucanae, using data obtained with the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope. Globular clusters are expected to emit gamma rays because of the large populations of millisecond pulsars that they contain. The spectral shape of 47 Tucanae is consistent with gamma-ray emission from a population of millisecond pulsars. The observed gamma-ray luminosity implies an upper limit of 60 millisecond pulsars present in 47 Tucanae.