Background: In December 2019, the coronavirus disease 2019 (COVID-19) outbreak occurred in Wuhan. Data on the clinical characteristics and outcomes of patients with severe COVID-19 are limited. Objective: We sought to evaluate the severity on admission, complications, treatment, and outcomes of patients with COVID-19. Methods: Patients with COVID-19 admitted to Tongji Hospital from January 26, 2020, to February 5, 2020, were retrospectively enrolled and followed-up until March 3, 2020. Potential risk factors for severe COVID-19 were analyzed by a multivariable binary logistic model. Cox proportional hazard regression model was used for survival analysis in severe patients. Results: We identified 269 (49.1%) of 548 patients as severe cases on admission. Older age, underlying hypertension, high cytokine levels (IL-2R, IL-6, IL-10, and TNF-a), and high lactate dehydrogenase level were significantly associated with severe COVID-19 on admission. The prevalence of asthma in patients with COVID-19 was 0.9%, markedly lower than that in the adult population of Wuhan. The estimated mortality was 1.1% in nonsevere patients and 32.5% in severe cases during the average 32 days of follow-up period. Survival analysis revealed that male sex, older age, leukocytosis, high lactate dehydrogenase level, cardiac injury, hyperglycemia, and highdose corticosteroid use were associated with death in patients with severe COVID-19.Conclusions: Patients with older age, hypertension, and high lactate dehydrogenase level need careful observation and early intervention to prevent the potential development of severe COVID-19. Severe male patients with heart injury, hyperglycemia, and high-dose corticosteroid use may have a high risk of death.

visible-to microwave-frequencies, [3][4][5][6] however, with rather small operation bandwidths. Likewise, 3D chiral dielectric photonic crystals [7][8][9][10][11] also show fairly small operation bandwidths.In sharp contrast, metallic helical metamaterials exhibit circular dichroism over an unmatched bandwidth of well above one octave. Starting with square arrays of single gold helices that function as broadband circular polarizers with high extinction ratio in the mid infrared, [ 12,13 ] recently research has led to more complex unit cells. For example, by tapering the helix radius along the helix axis, the extinction ratio and the bandwidth can be enhanced simultaneously. [ 14 ] Double-helical unit cells have also been proposed to lead to higher extinction ratios and enlarged bandwidths. [15][16][17][18] Circular polarization conversions are often unwanted for polarizer applications. They can be eliminated by recovering either threefold or fourfold rotational symmetry by intertwining three or four helices, respectively, within one unit cell of a lattice with the same rotational symmetry. [19][20][21][22][23] Applications beyond circular polarizers such as broadband absorbers [ 24 ] or chiral near-fi eld sources [ 25 ] have also been proposed.While for circular polarizers a large difference of the diagonal elements of the Jones transmission matrix is desired, chiral metamaterials can also be designed to exhibit strong circular polarization conversions corresponding to the off-diagonal elements. Even though converting one circular polarization to the other can be achieved by half-wave plates at visible frequencies, these wave plates are often limited in bandwidth and not readily available at many other frequency ranges.Furthermore, a large difference in these off-diagonal elements can be of interest, both in linear and circular polarization basis. This effect is often referred to as "asymmetric transmission" due to the symmetry of the Jones transmission matrix. Applications like diode-like devices exploiting asymmetric Jones matrices have been proposed. [ 26 ] Metamaterial designs with highly asymmetric polarization conversions have been realized for linearly polarized light, both at infrared-and terahertz-frequencies. [ 27,28 ] More recently, many more designs for linearly polarized light have been proposed with both high extinction ratios and large bandwidths. [29][30][31][32][33] Asymmetric polarization conversions for circular polarization, on the other hand, has only been reported recently, however, with generally much Metallic helical metamaterials give rise to broadband and scalable chirooptical effects orders of magnitude higher than found in nature. While arrays of gold helices have been suggested as compact circular polarizers, where a large difference of the diagonal elements of the Jones transmission matrix is desired, chiral metamaterials can also be designed to exhibit strong circularpolarization conversions. Here, a novel helical metamaterial design, exhibiting asymmetric, broadband circular-polari...

Appropriate infant and young child feeding could reduce morbidity and mortality and could improve cognitive development of children. However, nationwide data on exclusive breastfeeding and complementary feeding status in China are scarce. The aim of this study was to assess current exclusive breastfeeding and complementary feeding status in China. A national representative survey (Chinese National Nutrition and Health Survey) of children aged under 6 years was done in 2013. Stratified multistage cluster sampling was used to select study participants. World Health Organization (WHO) infant and young child feeding indicators were firstly used to assess exclusive breastfeeding and complementary feeding practice nationwide. In total, 14,458 children aged under two years (0 to <730 days) were studied from 55 counties in 30 provinces in China. The crude exclusive breastfeeding rate under 6 months was 20.7% (908/4381) and the weighted exclusive breastfeeding rate was 18.6%. The crude prevalence of minimum dietary diversity, minimum meal frequency and minimum acceptable diet were 52.5% (5286/10,071), 69.8% (7027/10,071), and 27.4% (2764/10,071) among children aged 6–23 months, respectively. The weighted rate was 53.7%, 69.1%, and 25.1%, respectively. Residential area, household income and maternal education were positively associated with the three complementary feeding indicators. The exclusive breastfeeding rate under 6 months was low and complementary feeding practice was not optimal in China. Residential area, household income and maternal education might be used to target infants and young children to improve complementary feeding practice.

Background: The rapid outbreak of coronavirus disease 2019 (COVID-19) has turned into a public health emergency of international concern. Epidemiological research has shown that sex is associated with the severity of COVID-19, but the underlying mechanism of sex predisposition remains poorly understood. We aim to study the gendered differences in inflammation reaction, and the association with severity and mortality of COVID-19. Methods: In this retrospective study, we enrolled 548 COVID-19 inpatients from Tongji Hospital from 26 January to 5 February 2020, and followed up to 3 March 2020. Epidemiological, demographic and clinical features, and inflammatory indexes were collected and compared between males and females. The Cox proportional hazard regression model was applied to identify the gendered effect on mortality of COVID-19 after adjusting for age, comorbidity, and smoking history. The multiple linear regression method was used to explore the influence of sex on inflammation reaction. Results: Males had higher mortality than females did (22.2% vs 10.4%), with an hazard ratio of 1.923 (95% confidence interval, 1.181-3.130); elder age and comorbidity were significantly associated with decease of COVID-19 patients. Excess inflammation reaction was related to severity of COVID-19. Male patients had greater inflammation reaction, with higher levels of interleukin 10, tumor necrosis factor-α, lactose dehydrogenase, ferritin, and hyper-sensitive C-reactive protein, but a lower lymphocyte count than females adjusted by age and comorbidity. Conclusions: Sex, age, and comorbidity are critical risk factors for mortality of COVID-19. Excess innate immunity and proinflammation activity, and deficiency in adaptive immunity response promote males, especially elder males, to develop a

To define and characterize optical systems, obtaining the amplitude, phase, and polarization profile of optical beams is of utmost importance. Traditional polarimetry is well established to characterize the polarization state. Recently, metasurfaces have successfully been introduced as compact optical components. Here, we take the metasurface concept to the system level by realizing arrays of metalenses, allowing the determination of the polarization profile of an optical beam. We use silicon-based metalenses with a numerical aperture of 0.32 and a mean measured focusing efficiency in transmission mode of 28% at a wavelength of 1550 nm. Our system is extremely compact and allows for real-time beam diagnostics by inspecting the foci amplitudes. By further analyzing the foci displacements in the spirit of a Hartmann-Shack wavefront sensor, we can simultaneously detect phase-gradient profiles. As application examples, we diagnose the profiles of a radially polarized beam, an azimuthally polarized beam, and of a vortex beam.

In this paper, we proposed new structured metamaterials with multi-helical nanowires to construct circular polarizers with higher S/N ratios. Compared with the single-helical ones reported by J. K. Gansel et al. [Science 325, 1513 (2009), Opt. Express 18, 1059 (2010)], which has a lower S/N ratio (~10 dB) due to the high intensity conversion, the circular polarizers with the multi-helical structures have average two orders higher S/N ratios (~35 dB). Simultaneously, other optical performances, such as operation bands, average extinction ratios, are also improved.

The state of polarization (SOP) is the key characteristic of light; its evaluation is typically based on measurements of the Stokes parameters. However, conventional approaches often have bulky and complex optical systems with long acquisition times. In this Letter, an ultracompact polarimeter based on dielectric metasurfaces is proposed. The pixel of the proposed metasuface has four areas; each area acts not only as a polarization separator, but also a flat focusing lens. It can acquire a certain polarization component of the incident light and focus the component on the receiver. Therefore, the Stokes parameters of the incident light can be immediately determined through the data from the receiver, fully describing its SOP. The incident waves with different SOPs are simulated to demonstrate that the reconstructed Stokes parameters are in good agreement with the original ones.

Articles you may be interested inTheoretical study of high-Q Fano resonance and extrinsic chirality in an ultrathin Babinet-inverted metasurface J. Appl. Phys. 116, 153506 (2014); 10.1063/1.4898314 Using dual-band asymmetric transmission effect of 2D metamaterial to manipulate linear polarization state of electromagnetic waves AIP Advances 4, 097129 (2014); 10.1063/1.4896285 Polarization conversion in U-shaped chiral metamaterial with four-fold symmetry breaking Effective-medium models and experiments for extraordinary transmission in metamaterial-loaded waveguides