Saving Grace on Feathered Wings: Homing Pigeons in the First World War

Soldiers of the First World War came in all shapes and sizes. The humble homing pigeon is one of the more unique and critical examples of such. They served in the armed forces of both the Allies and the Central Powers. Used as a last-ditch form of communication, the homing pigeons were exceptional in the work of sending messages back and forth between the battle lines. Little has been written about their vital role and even less in the rigorous training the birds and their handlers both endured. Understanding their training is critical to understanding how the homing pigeons performed so well under the extreme conditions of combat

Best of Intentions?: Rinderpest, Containment Practices, and Rebellion in Rhodesia in 1896

Rinderpest was a deadly bovine virus that plagued cattle herds accross Europe and Asia for centuries. In the late 1880s to early 1890s, the virus found its way to Africa, where it wiped out thousands of non-immune cattle herds belonging to African pastoralists and agriculturalists. By February 1896, the virus had crossed the Rhodesian border along the Zambezi River and began killing off cattle owned by ethnic groups that included the Matabele and the Shona, as well as cattle owned by white settlers. In an effort to contain the virus, the British South African Company consulted with colonial officials in the Cape Colony, who in turn advised the local police in Rhodesia to practice quarantines of cattle herds and authorized the shooting of sick and healthy cattle in order to create a buffer zone against the virus. The harsh practices of the legalized killing of cattle, coupled with a pre-existing tense political situation, convinced the Matabele people to take an armed stand against the colonial state

Saving Grace on Feathered Wings: Homing Pigeons in the First World War

Soldiers of the First World War came in all shapes and sizes. The humble homing pigeon is one of the more unique and critical examples of such. They served in the armed forces of both the Allies and the Central Powers. Used as a last-ditch form of communication, the homing pigeons were exceptional in the work of sending messages back and forth between the battle lines. Little has been written about their vital role and even less in the rigorous training the birds and their handlers both endured. Understanding their training is critical to understanding how the homing pigeons performed so well under the extreme conditions of combat

A Moment in History Relevant to the Modern Era

April 6, 1917 is a date that deserves great recognition and remembrance in the United States. On that day, the United States chose to enter a war that it had previously so ardently tried to avoid. Upon entrance, the United States forged a new national identity that looked past racial and religious barriers with a new mission to protect global democracy. On April 6, 2017, the 100th anniversary of America entering the First World War, news and other media throughout the United States seemed to care so little about the significance of the date and unfortunately passed over an excellent history lesson. Despite the current division in the United States, the country has dealt with it before. Reforging a new national identity was the solution in 1917. Perhaps it is the solution needed in 2017

Best of Intentions?: Rinderpest, Containment Practices, and Rebellion in Rhodesia in 1896

Rinderpest was a deadly bovine virus that plagued cattle herds across Europe and Asia for centuries. In the late 1880’s-early 1890’s, the virus found its way to the African continent where it wreaked immense havoc among the unimmune herds of African pastoralists and agriculturalists. By February 1896, the virus had crossed the Rhodesian border along the Zambezi River and began killing off cattle owned by ethnic groups like the Matabele and Shona, as well as those owned by white settlers. In an effort to contain the virus, the British South African Company consulted with colonial officials from the Cape Colony, who in turn advised the local police in Rhodesia to practice quarantines of cattle herds and to begin legal mass killings of sick and healthy cattle to create a buffer zone. The harsh practices of legalized killings of cattle, coupled with an already pre-existing tense political situation, convinced the Matabele to take a stand against the colonial state in an act of rebellion

Intrapulmonary shunting and pulmonary gas exchange during normoxic and hypoxic exercise in healthy humans

Exercise-induced intrapulmonary arteriovenous shunting, as detected by saline contrast echocardiography, has been demonstrated in healthy humans. We have previously suggested that increases in both pulmonary pressures and blood flow associated with exercise are responsible for opening these intrapulmonary arteriovenous pathways. In the present study, we hypothesized that, although cardiac output and pulmonary pressures would be higher in hypoxia, the potent pulmonary vasoconstrictor effect of hypoxia would actually attenuate exercise-induced intrapulmonary shunting. Using saline contrast echocardiography, we examined nine healthy men during incremental (65W + 30 W/2 min) cycle exercise to exhaustion in normoxia and hypoxia (fraction of inspired O-2 = 0.12). Contrast injections were made into a peripheral vein at rest and during exercise and recovery (3-5 min postexercise) with pulmonary gas exchange measured simultaneously. At rest, no subject demonstrated intrapulmonary shunting in normoxia [ arterial P-O2 (Pa-O2) = 98 +/- 10 Torr], whereas in hypoxia (Pa-O2 = 47 +/- 5 Torr), intrapulmonary shunting developed in 3/9 subjects. During exercise, similar to 90% (8/9) of the subjects shunted during normoxia, whereas all subjects shunted during hypoxia. Four of the nine subjects shunted at a lower workload in hypoxia. Furthermore, all subjects continued to shunt at 3 min, and five subjects shunted at 5 min postexercise in hypoxia. Hypoxia has acute effects by inducing intrapulmonary arteriovenous shunt pathways at rest and during exercise and has longterm effects by maintaining patency of these vessels during recovery. Whether oxygen tension specifically regulates these novel pathways or opens them indirectly via effects on the conventional pulmonary vasculature remains unclear

An alternative hypothesis testing strategy for secondary phenotype data in case-control genetic association studies

Motivated by the challenges associated with accounting for the ascertainment when analyzing secondary phenotypes that are correlated with case-control status, Lin and Zeng have proposed a method that properly reflects the case-control sampling (Lin and Zeng, 2009). The Lin and Zeng method has the advantage of accurately estimating effect sizes for secondary phenotypes that are normally distributed or dichotomous. This method can be computationally intensive in practice under the null hypothesis when the likelihood surface that needs to be maximized can be relatively flat. We propose an extension of the Lin and Zeng method for hypothesis testing that uses proportional odds logistic regression to circumvent these computational issues. Through simulation studies, we compare the power and type-1 error rate of our method to standard approaches and Lin and Zeng's approach

Geometric counting on wavefront real spherical spaces

We provide $L^p$-versus $L^\infty$-bounds for eigenfunctions on a real spherical space $Z$ of wavefront type. It is shown that these bounds imply a non-trivial error term estimate for lattice counting on $Z$. The paper also serves as an introduction to geometric counting on spaces of the mentioned type. Section 7 on higher rank is new and extends the result from v1 to higher rank. Final version. To appear in Acta Math. Sinica.Comment: 46 page

On the equivalence of Eulerian and Lagrangian variables for the two-component Camassa-Holm system

The Camassa-Holm equation and its two-component Camassa-Holm system generalization both experience wave breaking in finite time. To analyze this, and to obtain solutions past wave breaking, it is common to reformulate the original equation given in Eulerian coordinates, into a system of ordinary differential equations in Lagrangian coordinates. It is of considerable interest to study the stability of solutions and how this is manifested in Eulerian and Lagrangian variables. We identify criteria of convergence, such that convergence in Eulerian coordinates is equivalent to convergence in Lagrangian coordinates. In addition, we show how one can approximate global conservative solutions of the scalar Camassa-Holm equation by smooth solutions of the two-component Camassa-Holm system that do not experience wave breaking

Wireless Communication using Unmanned Aerial Vehicles (UAVs): Optimal Transport Theory for Hover Time Optimization

In this paper, the effective use of flight-time constrained unmanned aerial vehicles (UAVs) as flying base stations that can provide wireless service to ground users is investigated. In particular, a novel framework for optimizing the performance of such UAV-based wireless systems in terms of the average number of bits (data service) transmitted to users as well as UAVs' hover duration (i.e. flight time) is proposed. In the considered model, UAVs hover over a given geographical area to serve ground users that are distributed within the area based on an arbitrary spatial distribution function. In this case, two practical scenarios are considered. In the first scenario, based on the maximum possible hover times of UAVs, the average data service delivered to the users under a fair resource allocation scheme is maximized by finding the optimal cell partitions associated to the UAVs. Using the mathematical framework of optimal transport theory, a gradient-based algorithm is proposed for optimally partitioning the geographical area based on the users' distribution, hover times, and locations of the UAVs. In the second scenario, given the load requirements of ground users, the minimum average hover time that the UAVs need for completely servicing their ground users is derived. To this end, first, an optimal bandwidth allocation scheme for serving the users is proposed. Then, given this optimal bandwidth allocation, the optimal cell partitions associated with the UAVs are derived by exploiting the optimal transport theory. Results show that our proposed cell partitioning approach leads to a significantly higher fairness among the users compared to the classical weighted Voronoi diagram. In addition, our results reveal an inherent tradeoff between the hover time of UAVs and bandwidth efficiency while serving the ground users