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China bears a heavy burden of AD costs, which greatly change the estimates of AD cost worldwide.

Introduction Neuronal‐derived exosomal Aβ42, T‐tau, and P‐T181‐tau have been demonstrated to be biomarkers of Alzheimer's disease (AD). However, no study has assessed the association of Aβ42, T‐tau, and P‐T181‐tau between exosomes and CSF. Methods This was a multicenter study with two‐stage design. The subjects included 28 AD patients, 25 aMCI patients, and 29 controls in the discovery stage; the results of which were confirmed in the validation stage (73 AD, 71 aMCI, and 72 controls). Results The exosomal concentrations of Aβ42, T‐tau, and P‐T181‐tau in AD group were higher than those in aMCI and control groups (all P < .001). The level of each exosomal biomarker was highly correlated with that in CSF. Discussion This study verified the agreement between CSF and blood exosomal biomarkers and confirmed that exosomal Aβ42, T‐tau, and P‐T181‐tau have the same capacity as those in CSF for the diagnosis of AD and aMCI.

Maximal signal and peak of high-frequency relic gravitational waves (GW's), recently expected by quintessential inflationary models, may be firmly localized in the GHz region, the energy density of the relic gravitons in critical units (i.e., h 2 0 Ω GW ) is of the order 10 −6 , roughly eight orders of magnitude larger than in ordinary inflationary models. This is just right best frequency band of the electromagnetic (EM) response to the high-frequency GW's in smaller EM detecting systems. We consider the EM response of a Gaussian beam passing through a static magnetic field to a high-frequency relic GW. It is found that under the synchroresonance condition, the first-order perturbative EM power fluxes will contain "left circular wave" and "right circular wave" around the symmetrical axis of the Gaussian beam, but the perturbative effects produced by the states of + polarization and × polarization of the relic GW have different properties, and the perturbations on behavior are obviously different from that of the background EM fields in the local regions. For the high-frequency relic GW with the typical parameters ν g = 10 10 Hz, h = 10 −30 in the quintessential inflationary models, the corresponding perturbative photon flux passing through the region 10 −2 m 2 would be expected to be 10 3 s −1 . This is largest perturbative photon flux we recently analyzed and estimated using the typical laboratory parameters. In addition, we also discuss geometrical phase shift generated by the high-frequency relic GW in the Gaussian beam and estimate possible physical effects.

Introduction: Exosomes are an emerging candidate for biomarkers of Alzheimer's disease (AD). This study investigated whether exosomal synaptic proteins can predict AD at the asymptomatic stage.

We consider the electromagnetic (EM) perturbative effects produced by the high-frequency gravitational waves (HFGWs) in the GHz band in a special EM resonance system, which consists of fractal membranes, a Gaussian beam (GB) passing through a static magnetic field.It is predicted, under the synchroresonance condition, coherence modulation of the HFGWs to the preexisting transverse components of the GB produces the transverse perturbative photon flux (PPF),which has three novel and important properties: (1)The PPF has maximum at a longitudinal symmetrical surface of the GB where the transverse background photon flux (BPF) vanishes; (2) the resonant effect will be high sensitive to the propagating directions of the HFGWs; (3) the PPF reflected or transmitted by the fractal membrane exhibits a very small decay compared with very large decay of the much stronger BPF. Such properties might provide a new way to distinguish and display the perturbative effects produced by the HFGWs. We also discuss the high-frequency asymptotic behavior of the relic GWs in the microwave band and the positive definite issues of their energy-momentum pseudo-tensor .

A coupling system between Gaussian type-microwave photon flux, static magnetic field and fractal membranes (or other equivalent microwave lenses) can be used to detect high-frequency gravitational waves (HFGWs) in the microwave band. We study the signal photon flux, background photon flux and the requisite minimal accumulation time of the signal in the coupling system. Unlike pure inverse Gertsenshtein effect (G-effect) caused by the HFGWs in the GHz band, the the electromagnetic (EM) detecting scheme (EDS) proposed by China and the US HFGW groups is based on the composite effect of the synchro-resonance effect and the inverse G-effect. Key parameters in the scheme include first-order perturbative photon flux (PPF) and not the second-order PPF; the distinguishable signal is the transverse first-order PPF and not the longitudinal PPF; the photon flux focused by the fractal membranes or other equivalent microwave lenses is not only the transverse first-order PPF but the total transverse photon flux, and these photon fluxes have different signal-to-noise ratios at the different receiving surfaces. Theoretical analysis and numerical estimation show that the requisite minimal accumulation time of the signal at the special receiving surfaces and in the background noise fluctuation would be ∼ 10 3 − 10 5 seconds for the typical laboratory condition and parameters of h r.m.s. ∼ 10 −26 − 10 −30 at 5GHz with bandwidth ∼1Hz. In addition, we review the inverse G-effect in the EM detection of the HFGWs, and it is shown that the EM detecting scheme based only on the pure inverse G-effect in the laboratory condition would not be useful to detect HFGWs in the microwave band. PACS numbers: 04.30Nk, 04.25Nx, 04.30Db, 04.80Nn a

IMPORTANCE Much remains unknown about the transmission dynamics of COVID-19. How the severity of the index case and timing of exposure is associated with disease in close contacts of index patients with COVID-19 and clinical presentation in those developing disease is not well elucidated.OBJECTIVES To investigate the association between the timing of exposure and development of disease among close contacts of index patients with COVID-19 and to evaluate whether the severity of the index case is associated with clinical presentation in close contacts who develop COVID-19. DESIGN, SETTING, AND PARTICIPANTSThis study used a large, population-based cohort of 730 individuals (index patients) who received a diagnosis of COVID-19 in Zhejiang Province, China, from January 8 to July 30, 2020, along with a contact tracing surveillance program. Field workers visited 8852 close contacts of the index patients and evaluated them for COVID-19 through August 2020. A timeline was constructed to characterize different exposure periods between index patients and their contacts. MAIN OUTCOMES AND MEASURESThe primary outcome was the attack rate of COVID-19, defined as the total number of new COVID-19 cases diagnosed among contacts of index patients divided by the total number of exposed contacts. A secondary outcome was asymptomatic clinical presentation among infected contacts. Relative risks were calculated to investigate risk factors for COVID-19 among contacts and asymptomatic clinical presentation among infected contacts. RESULTS Among 8852 close contacts (4679 male contacts [52.9%]; median age, 41 years [interquartile range, 28-54 years]) of 730 index patients (374 male patients [51.2%]; median age, 46 years [interquartile range, 36-56 years]), contacts were at highest risk of COVID-19 if they were exposed between 2 days before and 3 days after the index patient's symptom onset, peaking at day 0 (adjusted relative risk [ARR], 1.3; 95% CI, 1.2-1.5). Compared with being exposed to an asymptomatic index patient, the risk of COVID-19 among contacts was higher when they were exposed to index patients with mild (ARR, 4.0; 95% CI, 1.8-9.1) and moderate (ARR, 4.3; 95% CI, 1.9-9.7) cases of COVID-19. As index case severity increased, infected contacts were less likely to be asymptomatic (exposed to patient with mild COVID-19: ARR, 0.3; 95% CI, 0.1-0.9; exposed to patient with moderate COVID-19: ARR, 0.3; 95% CI, 0.1-0.8).CONCLUSIONS AND RELEVANCE This cohort study found that individuals with COVID-19 were most infectious a few days before and after symptom onset. Infected contacts of asymptomatic index patients were less likely to present with COVID-19 symptoms, suggesting that quantity of exposure may be associated with clinical presentation in close contacts.