Measurements of All-Particle Energy Spectrum and Mean Logarithmic Mass of Cosmic Rays from 0.3 to 30 PeV with LHAASO-KM2A

We present the measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays in the energy range of 0.3-30 PeV using data collected from LHAASO-KM2A between September 2021 and December 2022, which is based on a nearly composition-independent energy reconstruction method, achieving unprecedented accuracy. Our analysis reveals the position of the knee at 3.67±0.05±0.15  PeV. Below the knee, the spectral index is found to be -2.7413±0.0004±0.0050, while above the knee, it is -3.128±0.005±0.027, with the sharpness of the transition measured with a statistical error of 2%. The mean logarithmic mass of cosmic rays is almost heavier than helium in the whole measured energy range. It decreases from 1.7 at 0.3 PeV to 1.3 at 3 PeV, representing a 24% decline following a power law with an index of -0.1200±0.0003±0.0341. This is equivalent to an increase in abundance of light components. Above the knee, the mean logarithmic mass exhibits a power law trend towards heavier components, which is reversal to the behavior observed in the all-particle energy spectrum. Additionally, the knee position and the change in power-law index are approximately the same. These findings suggest that the knee observed in the all-particle spectrum corresponds to the knee of the light component, rather than the medium-heavy components.

[Clinical outcomes of endovascular therapy in acute stroke patients with anterior circulation tandem occlusions due to atherosclerosis and dissection]

Objective: To compare the clinical outcomes of endovascular therapy in acute stroke patients with anterior circulation tandem occlusions caused by atherosclerosis or dissection. Methods: A retrospective cohort study. A total of 98 patients with anterior circulation tandem lesions undergoing endovascular therapy in the Wuhan NO.1 Hospital (March 2016 to March 2022) were analyzed. Median age was 64(55,71) years old, and 82.7% (81/98 cases) were males. According to the lesion etiology, the patients were divided into atherosclerosis and dissection groups. The differences in clinical outcomes between the two groups were investigated, including favorable 90-day functional outcome (modified Rankin Scale score of 0-2), successful reperfusion (modified Thrombolysis in Cerebrovascular Infarction score of 2b-3), symptomatic intracranial hemorrhage, stroke-associated pneumonia, 90-day all-cause mortality, and average hospitalization days. Logistic regression analysis was used to adjust for potential confounders affecting functional outcomes in both groups, and to determine odds ratios and 95% confidence intervals. Results: Seventy-one patients were grouped into the atherosclerotic cause and 27 into the dissection cause cohorts. The rate of favorable 90-day functional outcome was 43.7% (31/71 cases) in the atherosclerosis group versus 55.6% (15/27 cases) in the dissection group (adjusted odds ratio=1.339; 95% confidence interval, 0.374-4.798; P=0.654). No significant differences were found in other clinical outcomes between the two groups (all P>0.05). Conclusion: The clinical prognosis of patients with tandem lesions caused by atherosclerotic stenosis or artery dissection was similar after endovascular therapy. Future studies are still needed to verify our results.

Measurement of Ultra-High-Energy Diffuse Gamma-Ray Emission of the Galactic Plane from 10 TeV to 1 PeV with LHAASO-KM2A

The diffuse Galactic γ-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this Letter, we report the measurements of diffuse γ rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner (15°10  TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of -2.99±0.04, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of ∼3 than the prediction. A similar spectrum with an index of -2.99±0.07 is found in the outer Galaxy region, and the absolute flux for 10≲E≲60  TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations.

A tera-electron volt afterglow from a narrow jet in an extremely bright gamma-ray burst

Some gamma-ray bursts (GRBs) have a tera-electron volt (TeV) afterglow, but the early onset of this has not been observed. We report observations with the Large High Altitude Air Shower Observatory of the bright GRB 221009A, which serendipitously occurred within the instrument field of view. More than 64,000 photons >0.2 TeV were detected within the first 3000 seconds. The TeV flux began several minutes after the GRB trigger, then rose to a peak about 10 seconds later. This was followed by a decay phase, which became more rapid ~650 seconds after the peak. We interpret the emission using a model of a relativistic jet with half-opening angle ~0.8°. This is consistent with the core of a structured jet and could explain the high isotropic energy of this GRB.

Oligomeric β-Amyloid Suppresses Hippocampal γ-Oscillations through Activation of the mTOR/S6K1 Pathway

Neuronal synchronization at gamma frequency (30-100 Hz: γ) is impaired in early-stage Alzheimer's disease (AD) patients and AD models. Oligomeric Aβ_1-42 caused a concentration-dependent reduction of γ-oscillation strength and regularity while increasing its frequency. The mTOR1 inhibitor rapamycin prevented the Aβ_1-42-induced suppression of γ-oscillations, whereas the mTOR activator leucine mimicked the Aβ_1-42-induced suppression. Activation of the downstream kinase S6K1, but not inhibition of eIF4E, was required for the Aβ_1-42-induced suppression. The involvement of the mTOR/S6K1 signaling in the Aβ_1-42-induced suppression was confirmed in Aβ-overexpressing APP/PS1 mice, where inhibiting mTOR or S6K1 restored degraded γ-oscillations. To assess the network changes that may underlie the mTOR/S6K1 mediated γ-oscillation impairment in AD, we tested the effect of Aβ_1-42 on IPSCs and EPSCs recorded in pyramidal neurons. Aβ_1-42 reduced EPSC amplitude and frequency and IPSC frequency, which could be prevented by inhibiting mTOR or S6K1. These experiments indicate that in early AD, oligomer Aβ_1-42 impairs γ-oscillations by reducing inhibitory interneuron activity by activating the mTOR/S6K1 signaling pathway, which may contribute to early cognitive decline and provides new therapeutic targets.

[Risk factors of recurrence or metastasis in patients with medullary thyroid carcinoma]

Objective: To analyze the risk factors of recurrence or metastasis of medullary thyroid carcinoma (MTC) and the influencing factors of disease-free survival (DFS). Methods: The clinicopathological data of MTC patients who visited Tianjin Medical University Cancer Institute and Hospital and underwent surgery from August 2014 to August 2019 were retrospectively analyzed. The patients were divided into recurrence or metastasis group and no recurrence or metastasis group. Multivariate logistic regression analysis was used to analyze the risk factors for recurrence or metastasis. Kaplan-Meier survival analysis and Cox regression analysis were used to determine the risk factors of DFS. Results: A total of 158 MTC patients were enrolled in final analysis, including 83 females and 75 males, with a median age of 52 (19-74) years. There were 146 cases of sporadic MTC (92.4%) and 12 cases of familial MTC (7.6%), respectively. Bilateral thyroid lesions presented in 33 cases (20.9%) and multiple lesions presented in 57 cases (36.1%), respectively. The median follow-up time was 59.7 (10.0-93.0) months and the median DFS was 55.5 (0-92.9) months. Presence of multifocality, the largest tumor size>2 cm, T3/4, N1b, clinical stage Ⅲ/Ⅳ, lymph node metastasis ratio (LNR)>0.3, preoperative calcitonin>2 000 ng/L, postoperative calcitonin>40 ng/L and no biochemical cure were significantly correlated with the recurrence or metastasis and DFS of MTC (all P<0.05). Clinical stage Ⅲ/Ⅳ (OR=36.57, 95%CI: 1.33-1 006.98, P=0.033), the largest tumor size>2 cm (OR=5.81, 95%CI: 1.01-33.33, P=0.049), multifocality (OR=3.64, 95%CI: 1.03-12.88, P=0.045) and postoperative calcitonin>40 ng/L (OR=15.03, 95%CI: 1.39-162.61, P=0.026) were independent risk factors of recurrence or metastasis. Clinical stage Ⅲ/Ⅳ (HR=19.39, 95%CI:1.40-268.19, P=0.027), the largest tumor size>2 cm (HR=3.64, 95%CI: 1.02-13.02, P=0.047) and postoperative calcitonin>40 ng/L (HR=10.68, 95%CI: 1.34-84.95, P=0.025) were influencing factors for DFS (all P<0.05). Conclusion: The larger tumor size, advanced clinical stage and higher postoperative calcitonin at the initial treatment of MTC are risk factors for recurrence or metastasis and influencing factors for DFS.

Constraints on Heavy Decaying Dark Matter from 570 Days of LHAASO Observations

The kilometer square array (KM2A) of the large high altitude air shower observatory (LHAASO) aims at surveying the northern γ-ray sky at energies above 10 TeV with unprecedented sensitivity. γ-ray observations have long been one of the most powerful tools for dark matter searches, as, e.g., high-energy γ rays could be produced by the decays of heavy dark matter particles. In this Letter, we present the first dark matter analysis with LHAASO-KM2A, using the first 340 days of data from 1/2-KM2A and 230 days of data from 3/4-KM2A. Several regions of interest are used to search for a signal and account for the residual cosmic-ray background after γ/hadron separation. We find no excess of dark matter signals, and thus place some of the strongest γ-ray constraints on the lifetime of heavy dark matter particles with mass between 10^{5} and 10^{9}  GeV. Our results with LHAASO are robust, and have important implications for dark matter interpretations of the diffuse astrophysical high-energy neutrino emission.

Exploring Lorentz Invariance Violation from Ultrahigh-Energy γ Rays Observed by LHAASO

Recently, the LHAASO Collaboration published the detection of 12 ultrahigh-energy γ-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV γ rays from astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy γ rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of the LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 10^{5} times the Planck scale M_{Pl} and that the second-order LIV scale is >10^{-3}M_{Pl}. Both limits improve by at least one order of magnitude the previous results.

Peta-electron volt gamma-ray emission from the Crab Nebula

The Crab Nebula is a bright source of gamma rays powered by the Crab Pulsar's rotational energy through the formation and termination of a relativistic electron-positron wind. We report the detection of gamma rays from this source with energies from 5 × 10^-4 to 1.1 peta-electron volts with a spectrum showing gradual steepening over three energy decades. The ultrahigh-energy photons imply the presence of a peta-electron volt electron accelerator (a pevatron) in the nebula, with an acceleration rate exceeding 15% of the theoretical limit. We constrain the pevatron's size between 0.025 and 0.1 parsecs and the magnetic field to ≈110 microgauss. The production rate of peta-electron volt electrons, 2.5 × 10³⁶ ergs per second, constitutes 0.5% of the pulsar spin-down luminosity, although we cannot exclude a contribution of peta-electron volt protons to the production of the highest-energy gamma rays.

Metformin Ameliorates Synaptic Defects in a Mouse Model of AD by Inhibiting Cdk5 Activity

Cyclin-dependent kinase 5 (Cdk5) is a serine/threonine kinase that is activated by the neuron-specific activators p35/p39 and plays important roles in neuronal development, synaptic plasticity, and cognitive behavior. However, the proteolytic cleavage of p35 to p25 leads to prolonged and aberrant Cdk5 activation and results in synaptic depression, highly mimicking the early pathology of Alzheimer’s disease (AD). Therefore, Cdk5 inhibition is a potential promising strategy for AD drug development. Here in the present study, we showed that metformin, the most widely used drug for type 2 diabetes, suppressed Cdk5 hyper-activation and Cdk5-dependent tau hyper-phosphorylation in the APP/PS1 mouse hippocampus. We also identified the underlying molecular and cellular mechanism that metformin prevented Cdk5 hyper-activation by inhibiting the calpain-dependent cleavage of p35 into p25. Moreover, chronic metformin treatment rescued the core phenotypes in APP/PS1 mice as evidenced by restored spine density, surface GluA1 trafficking, Long-term potentiation (LTP) expression, and spatial memory. Altogether our study discovered an unidentified role of metformin in suppressing Cdk5 hyper-activation and thus preventing AD pathogenesis and suggested that metformin is a potential promising AD therapeutic drug.

Amorphophallus konjac anthracnose caused by Colletotrichum siamense in China

AIMS

Amorphophallus konjac is an important commercial crop grown in China because it is the only plant species which is rich in glucomannan concentration. Recently, an outbreak of anthracnose (incidence ranging from 10-15%) was observed in a field survey conducted from June to August 2018. This study aims to identify the causal agent of A. konjac anthracnose.

METHODS AND RESULTS

The pathogen was isolated on potato dextrose agar (PDA) medium. The fungal colony on PDA was greyish to dark grey. Conidia were falcate, one-celled and hyaline. Based on the micro-morphological and cultural characteristics, the pathogen was identified as Colletotrichum sp. blast search and phylogenetic analysis of the ITS, GAPDH, CHS1, ACT, CAL and TUB2 genes revealed the pathogen as Colletotrichum siamense. Koch's postulates were conducted on 2-month konjac leaves with conidial suspension. Development of typical anthracnose disease was recorded 5 days after inoculation and the pathogen's identity was confirmed by re-isolation and molecular identification.

CONCLUSIONS

Amorphophallus konjac anthracnose was caused by C. siamense in China.

SIGNIFICANCE AND IMPACT OF THE STUDY

Identification of causal agent of A. konjac anthracnose will be helpful in designing effective disease control strategies.

Acute Ethanol Inhibition of γ Oscillations Is Mediated by Akt and GSK3β

Hippocampal network oscillations at gamma band frequency (γ, 30-80 Hz) are closely associated with higher brain functions such as learning and memory. Acute ethanol exposure at intoxicating concentrations (≥50 mM) impairs cognitive function. This study aimed to determine the effects and the mechanisms of acute ethanol exposure on γ oscillations in an in vitro model. Ethanol (25-100 mM) suppressed kainate-induced γ oscillations in CA3 area of the rat hippocampal slices, in a concentration-dependent, reversible manner. The ethanol-induced suppression was reduced by the D1R antagonist SCH23390 or the PKA inhibitor H89, was prevented by the Akt inhibitor triciribine or the GSk3β inhibitor SB415286, was enhanced by the NMDA receptor antagonist D-AP5, but was not affected by the MAPK inhibitor U0126 or PI3K inhibitor wortmanin. Our results indicate that the intracellular kinases Akt and GSk3β play a critical role in the ethanol-induced suppression of γ oscillations and reveal new cellular pathways involved in the ethanol-induced cognitive impairment.

Nicotinic modulation of Ca2+ oscillations in rat cortical neurons in vitro

The roles of nicotine on Ca2+ oscillations [intracellular Ca2+ ([Ca2+]i) oscillation] in rat primary cultured cortical neurons were studied. The spontaneous [Ca2+]i oscillations (SCO) were recorded in a portion of the neurons (65%) cultured for 7–10 days in vitro. Application of nicotine enhanced [Ca2+]i oscillation frequency and amplitude, which were reduced by the selective α4β2-nicotinic acetylcholine receptors (nAChRs) antagonist dihydro-β-erythroidine (DHβE) hydrobromide, and the selective α7-nAChRs antagonist methyllycaconitine citrate (MLA, 20 nM). DHβE reduced SCO frequency and prevented the nicotinic increase in the frequency. DHβE somewhat enhanced SCO amplitude and prevented nicotinic increase in the amplitude. MLA (20 nM) itself reduced SCO frequency without affecting the amplitude but blocked nicotinic increase in [Ca2+]i oscillation frequency and amplitude. Furthermore, coadministration of both α4β2- and α7-nAChRs antagonists completely prevented nicotinic increment in [Ca2+]i oscillation frequency and amplitude. Thus, our results indicate that both α4β2- and α7-nAChRs mediated nicotine-induced [Ca2+]i oscillations, and two nAChR subtypes differentially regulated SCO.

First Report of Streptomyces galilaeus Associated with Common Scab in China

During a survey of potato scab pathogens in China from 2003 to 2012, a new pathogen was found in Shanxi and Neimenggu provinces. The incidence was approximately 20% of all recovered strains. The lesions caused by the pathogen were slightly raised and similar to those caused by Streptomyces scabies (3). Lesions were excised (approximately 10 mm³) from 40 infected tubers, surface-disinfested with 0.3% NaOCl for 30 s, rinsed in sterile water three times, cut into 5 mm³, then sliced into 1-mm pieces, and plated on water agar amended with ampicillin (50 μg/ml). Plates were incubated at 28°C in the dark for 4 days. The spores of Streptomyces sp. strains growing from the tuber pieces were collected from single bacterial colonies and cultured on oatmeal agar. To fulfill Koch's postulates, one strain, CPS-2, was grown at 28°C for 10 days and the spores were washed from the plates as inoculum. One hundred milliliters of inoculum (1 × 10⁵ CFU/ml) was mixed with autoclaved soil and vermiculite (1:1) in each pot (15 cm in diameter). Cut tubers were planted in the pots (potato cv. Favorita, one plant per pot, five replicates) and grown under greenhouse conditions (22 ± 5°C). Typical common scab symptoms consisting of small, brown, raised lesions developed on potato tubers 12 weeks after planting. The same strain was re-isolated from the lesions of the new scabby tubers. Non-inoculated plants, treated as described above, but without strain CPS-2, remained healthy. The CPS-2 strain was identified based on morphological and physiological characterization and 16S rDNA sequence. On yeast-malt extract agar, the test strain produced grayish-white aerial hypha, reddish brown substrate mycelium and pigments, and loose spiral spore chains. Spores were smooth and were 0.8 to 0.9 × 1.1 to 1.2 μm in size (diameter and length). The ability of the strain to use single sources of carbon and nitrogen was verified according to the International Streptomyces project (4). The strain grew in media supplemented with L-arabinose, D-fructose, D-glucose, rhamnose, raffinose, meso-inositol, sucrose, and D-xylose, but not D-mannitol. It used L-hydroxyproline, L-methionine, and L-histidine, and produced melanin on tyrosine and peptone yeast extract agar. The strain did not grow at a pH less than 5.0 and was sensitive to streptomycin (20 μg/ml), phenol (0.1%), and crystal violet (0.5 μg/mL), but not to penicillin (10 IU/ml). The strain also produced hydrogen sulfide. The biological characteristics of strain CPS-2 were in accord with Streptomyces galilaeus. CPS-2 produced thaxtomin A in oatmeal liquid medium and the txt AB gene fragment was successfully amplified using specific primers (2). The 16S rDNA sequence of CPS-2 was amplified by PCR with primers 16S1-F: 5'-CATTCACGGAGAGTTTGATCC-3' and 16S1-R: 5'-AGAAAGGAGGTGATCCAGCC-3' (1) and sequenced. A BLAST search of the 16S rDNA sequence for CPS-2 was conducted using the NCBI GenBank database, resulting in 99.8% similarity to S. galilaeus (NR_040857). The 16S rDNA sequence for CPS-2 (1,388 bp) was deposited in GenBank (AY621378). To our knowledge, this is the first report of S. galilaeus causing common scab of potato in China. References: (1) R. A. Bukhalid et al. Appl. Environ. Microbiol. 68:738, 2002. (2) R. Flores-González et al. Plant Pathol. 57:162, 2008. (3) D. H. Lambert and R. Loria. Int. J. Syst. Bacteriol. 39:387, 1989. (4) E. B. Shirling and D. Gottlieb. Int. J. Syst. Bacteriol. 16:313, 1966.

Differential features of patients with mutations in two COX assembly genes, SURF-1 and SCO2

We screened 41 patients with undiagnosed encephalomyopathies and cytochrome c oxidase (COX) deficiency for mutations in two COX assembly genes, SURF-1 and SCO2; 6 patients had mutations in SURF-1 and 3 had mutations in SCO2. All of the mutations in SURF-1 were small-scale rearrangements (deletions/insertions); 3 patients were homozygotes and the other 3 were compound heterozygotes. All patients with SCO2 mutations were compound heterozygotes for nonsense or missense mutations. All of the patients with mutations in SURF-1 had Leigh syndrome, whereas the 3 patients with SCO2 mutations had a combination of encephalopathy and hypertrophic cardiomyopathy, and the neuropathology did not show the typical features of Leigh syndrome. In patients with SCO2 mutations, onset was earlier and the clinical course and progression to death more rapid than in patients with SURF-1 mutations. In addition, biochemical and morphological studies showed that the COX deficiency was more severe in patients with SCO2 mutations. Immunohistochemical studies suggested that SURF-1 mutations result in similarly reduced levels of mitochondrial-encoded and nuclear-encoded COX subunits, whereas SCO2 mutations affected mitochondrial-encoded subunits to a greater degree. We conclude that patients with mutations in SURF-1 and SCO2 genes have distinct phenotypes despite the common biochemical defect of COX activity.

Remarkable enhancement of antioxidant activity of vitamin C in an artificial bilayer by making it lipo-soluble

The reaction kinetics between 4-palmitoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO-16) and vitamin C (VC) and its lipophilic derivative ascorbyl-6-palmitate (VC-16) was studied by stopped-flow ESR spectroscopy in a synthetic surfactant vesicle sodium 1-pentadecyl hexadecyl sulfate (SPHS). TEMPO-16 reacted with VC very slowly and showed a biphasic first-order kinetics with rate constants of 9.6 x 10(-4) and 2.5 x 10(-4) s-1, corresponding to diffusion of TEMPO-16 from the external monolayer of SPHS to the bulk water and flip-flop of TEMPO-16 from the internal to external monolayer of the vesicle, respectively. On the other hand, the reaction of TEMPO-16 with VC-16 was second-order and over three orders of magnitude faster than that with VC, presumably due to VC-16 induced fusion of the vesicle.