This manuscript presents a 50 Ω microstrip-fed quad-element high isolated ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna with band-notched characteristics. The overall area of the proposed structure is 0.33λo × 0.33λo mm2 (where λo depicts the free space wavelength corresponding to the lower cutoff frequency, i.e. 2.54 GHz), etched on an FR-4 substrate of thickness 0.8 mm. The top layer has four semicircular disc-shaped radiating elements that are identical and orthogonal to obtain better inter-element isolation and compactness. A reverse two-shaped slot is etched onto the radiating patches to attain a band-rejection capability. Moreover, a decoupling structure is also placed at the top layer to suppress the unwanted surface waves. The bottom layer consists of a ground plane, which is further modified with quasi-self complementary and meandered line slots. A rectangular slot is also etched below the feed line to better match the impedance near the lower cutoff frequencies. The simulated reflection coefficients (S11) of the proposed antenna are less than −10 dB over 2.54 to 10.74 GHz frequencies except at 3.37 to 4.15 GHz (WiMAX/C band), and the simulated inter-port isolation (S21) is greater than −15 dB over the entire UWB range of frequencies (3.1 to 10.6 GHz). Also, the measured S-parameter results well agreed with the simulated ones. Furthermore, the simulation study of the 20-element UWB-MIMO antenna is also investigated using the proposed quad-element structure.

Numerous studies have characterised the establishments registered with meal delivery apps (MDA) in several countries. However, little evidence is available regarding these platforms in Latin America (LA). The purpose of this study is to characterise food establishments registered with an MDA in nine LA cities. The establishments (n 3339) were characterised by the following keyword groups: ‘Typical cuisine’, ‘Meat and fish’, ‘Snacks’, ‘Breakfast’, ‘Desserts’ and ‘Healthy’. In addition, we identified the marketing strategies present in the establishments’ advertisements: photos, discounts and free delivery. Mexico City had the highest number of establishments registered with MDA (773), followed by Bogotá (655), Buenos Aires (567) and São Paulo (454). There is a direct relationship between the number of inhabitants of the cities and the number of the registered establishments. ‘Snacks’ was the keyword group most used by establishments in five of the nine cities. Establishments in two cities were most often characterised by the terms ‘Typical cuisine’ (Mexico City and Santiago de Chile) and ‘Meats and fish’ (Quito and San Jose). Photos were present in the advertisements of at least 84·0 % of the establishments. In addition, at least 40 % of establishments in Montevideo, Bogotá, São Paulo, Lima and Santiago de Chile offered discounts. Free delivery was present in at least 50 % of establishments in Quito, San Jose, Mexico City, Santiago de Chile and Lima. Photos were also the most common marketing strategy used by the establishments classified in all groups of keywords, while free delivery and discounts differed among them.

How do White Americans evaluate the politics of belonging in the United States across different ethnoreligious identity categories? This paper examines this question through two competing frameworks. On the one hand, given the salience of anti-Muslim attitudes in the United States, we consider whether White Americans penalize Muslim immigrants to the United States regardless of their ethnoracial background. On the other hand, Muslim identity is often conflated by the general public with Middle Eastern and North African (MENA) ethnoracial identity. We argue MENA-Muslim identity should be understood through the lens of intersectionality. In this case, White Americans may penalize MENA-Muslims immigrants to the United States more than Muslims from other ethnoracial groups. We test these two frameworks through a conjoint experimental design wherein respondents are asked to evaluate immigrants and indicate to whom the United States should give a green card—signaling legal belonging—and how likely the immigrant is to assimilate into America—signaling cultural belonging. Although White Americans believe White Muslims may assimilate better to the United States relative to MENA-Muslims, race does not moderate how White Americans evaluate who should be allowed to belong in the United States.

This article argues that two words in line 8.612 of the Aeneid, promissa and perfecta, have been transposed since the poem's composition, and that the restoration of their correct order yields a preferable sense. This corruption would have happened at an early stage in the poem's transmission, but there is some reason to believe that Servius’ comment on the verse reflects its original state.

The Frobenius–Schur indicators of characters in a real $2$-block with dihedral defect groups have been determined by Murray [‘Real subpairs and Frobenius–Schur indicators of characters in 2-blocks’, J. Algebra 322 (2009), 489–513]. We show that two infinite families described in his work do not exist and we construct examples for the remaining families. We further present some partial results on Frobenius–Schur indicators of characters in other tame blocks.

We developed a do-it-yourself test protocol using commercial Bacillus atrophaeus spores to assess the efficacy of ultraviolet-C (UV-C) light room-decontamination devices. Overall, 4 UV-C devices reduced B. atrophaeus by ≥3 log10 colony-forming units in 10 minutes, whereas a smaller device required 60 minutes. Of 10 in-use devices, only 1 was ineffective.

In many countries, the structure of wages and the labor law legislation are completely different for public and private sector employees. In this paper, we develop a general equilibrium overlapping generations model to study the effect of such differences on household savings and labor supply. To conduct our analysis, first we use microdata from two Brazilian household surveys to document that civil servants save and work significantly less than their counterparts in the private sector. Second, we use matched employer–employee microdata from Brazil (RAIS) to document differences between the two sectors in terms of wage and unemployment risk. Then, we calibrate the model to be consistent with micro and macro evidence for Brazil. Our counterfactual exercises show that differences in wages characteristics and labor law legislation account for nearly 70% of the gap in savings between civil servants and private sector workers, and 57% of the gap in labor supply. In addition, we find that eliminating those differences can produce sizable increase on aggregate savings, employment, and welfare.

In this paper, we consider the dynamical behaviour of a reaction–diffusion model for a population residing in a one-dimensional habit, with emphasis on the effects of boundary conditions and protection zone. We assume that the population is subjected to a strong Allee effect in its natural domain but obeys a monostable nonlinear growth in the protection zone $[L_1,\, L_2]$ with two constants satisfying $0\leq L_1< L_2$, and the general Robin condition is imposed on $x=0$ (i.e. $u(t,\,0)=bu_x(t,\,0)$ with $b\geq 0$). We show the existence of two critical values $0< L_*\leq L^*$, and prove that a vanishing–transition–spreading trichotomy result holds when the length of protection zone is smaller than $L_*$; a transition–spreading dichotomy result holds when the length of protection zone is between $L_*$ and $L^*$; only spreading happens when the length of protection zone is larger than $L^*$. Based on the properties of $L_*$, we obtain the precise strategies for an optimal protection zone: if $b$ is large (i.e. $b\geq 1/\sqrt {-g'(0)}$), the protection zone should start from somewhere near $0$; while if $b$ is small (i.e. $b< 1/\sqrt {-g'(0)}$), then the protection zone should start from somewhere away from $0$, and as far away from $0$ as possible.

Let $\mathcal {F}$ be a hereditary collection of finite subsets of $\mathbb {N}$. In this paper, we introduce and characterize $\mathcal {F}$-(almost) greedy bases. Given such a family $\mathcal {F}$, a basis $(e_n)_n$ for a Banach space X is called $\mathcal {F}$-greedy if there is a constant $C\geqslant 1$ such that for each $x\in X$, $m \in \mathbb {N}$, and $G_m(x)$, we have

$$ \begin{align*} \|x - G_m(x)\|\ \leqslant\ C \inf\left\{\left\|x-\sum_{n\in A}a_ne_n\right\|\,:\, |A|\leqslant m, A\in \mathcal{F}, (a_n)\subset \mathbb{K}\right\}. \end{align*} $$

$G_m(x)$

$\mathbb {K}$

$\mathcal {F}$

$\mathcal {F}$

$\mathcal {F}$

$\mathcal {F}$

$\mathcal {F}$

$\mathcal {F}$

Furthermore, we provide several examples of bases that are nontrivially $\mathcal {F}$-greedy. For a countable ordinal $\alpha $, we consider the case $\mathcal {F}=\mathcal {S}_{\alpha }$, where $\mathcal {S}_{\alpha }$ is the Schreier family of order $\alpha $. We show that for each $\alpha $, there is a basis that is $\mathcal {S}_{\alpha }$-greedy but is not $\mathcal {S}_{\alpha +1}$-greedy. In other words, we prove that none of the following implications can be reversed: for two countable ordinals $\alpha < \beta $,

$$ \begin{align*} \mbox{quasi-greedy}\ \Longleftarrow\ \mathcal{S}_{\alpha}\mbox{-greedy}\ \Longleftarrow\ \mathcal{S}_{\beta}\mbox{-greedy}\ \Longleftarrow\ \mbox{greedy}. \end{align*} $$

In an influential recent study, Broockman and Skovron (2018) found that American politicians consistently overestimate the conservativeness of their constituents on a host of issues. Whether this conservative bias in politicians’ perceptions of public opinion is a uniquely American phenomenon is an open question with broad implications for the quality and nature of democratic representation. We investigate it in four democracies: Belgium, Canada, Germany, and Switzerland. Despite these countries having political systems that differ greatly, we document a strong and persistent conservative bias held by a majority of the 866 representatives interviewed. Our findings highlight the conservative bias in elites’ perception of public opinion as a widespread regularity and point toward a pressing need for further research on its sources and impacts.

While scholars have focused extensively on the consequences of partnerships between interest groups, less attention has been paid to the historical dynamics shaping when, how, and why such groups unite. This is especially true of “unexpected” partnerships, which unite groups with seemingly little in common. Such partnerships are important, as they can reshape to an unusual degree which actors, issues, and ideas “fit together” politically. We address the puzzle of how unexpected group partnerships form through case studies of previously non-existent alliances between labor unions and the gay/lesbian rights movement in the United States and United Kingdom in the 1970s and 1980s. Using these cases, we produce a theory arguing that unexpected partnerships are a product of a favorable political opportunity structure—present when each group experiences shared threats and mutual vulnerabilities—and the actions of entrepreneurial group leaders, who forge cross-group identities, accentuate shared ideological convictions, and build institutional ties.

To preserve the functioning of WTO dispute settlement following the blockage of the Appellate Body, a sub-set of WTO Members created the Multi-Party Interim Appeal Arbitration Arrangement (MPIA). In the wake of the first appeal award rendered under the MPIA, this contribution describes how the MPIA process works and lists some of the innovations that can be found in the first MPIA procedure. More innovations can be expected as arbitration under Article 25 of the Dispute Settlement Understanding (DSU) (be it ad hoc or under the MPIA) can be adjusted and molded case-by-case by the disputing parties in their appeal arbitration agreements. In this sense, the MPIA can serve not only as an interim stop-gap to preserve WTO dispute settlement. It can also function as a laboratory to explore and test new ways of making WTO dispute settlement more efficient and in line with WTO Members' goals and interests: experimental reform by doing, rather than one-off, formal DSU review.