The Role and Problems of Small Business

Jordens befolkning ökar i snabb takt och stadsodlingar kan vara ett sätt att förse den ökande populationen med mat. Hur byggnadsintegrerade stadsodlingar, med fokus på tak, kan kopplas till hållbarhet undersöks i denna rapport. Den nuvarande situationen i Afrika och Nordamerika undersöks och frågeställningen som besvaras är: Hur skiljer sig prioriteringen av olika dimensioner av hållbarhet vid olika förutsättningar för urbana byggnadsintegrerade odlingar i Afrika och Nordamerika? Vilka aspekter av hållbarhet som kopplas till byggnadsintegrerade stadsodlingar bestäms till ekologiska, sociala och ekonomiska. Stadsodlingar kan också delas in i fyra olika verksamhetsplaner, av vilka institutionella odlingar, kommersiella odlingar och community farms analyseras. Resultatet visar att Afrika och Nordamerika har olika förutsättningar för att stadsodling ska vara en hållbar lösning. Afrika består idag av 1.1 miljarder människor vilket beräknas stiga till 2.4 miljarder år 2050. Klimatet är torrt på de flesta platser och en stor del av befolkningen lever i fattigdom och svält. Nordamerika har ett tempererat klimat med fyra årstider, och befolkningen kommer att ligga på en stabil nivå fram till år 2050. Nordamerika räknas som ett mer utvecklat land, vilket innebär att de ekonomiska förutsättningarna här är större än de är i Afrika. Det finns en större andel stora odlingar i Nordamerika jämfört med Afrika, där odlingarna är mindre till ytan. Det finns också fler exempel på byggnadsintegrerad stadsodling i Nordamerika än i Afrika. Slutsatserna blir att byggnadsintegrerade stadsodlingar har bättre potential att utvecklas i Nordamerika då de kräver en stor investeringskostnad vid anläggning. För att byggnadsintegrerade stadsodlingar ska bli en mer hållbar och utbredd lösning både i Afrika och Nordamerika krävs att anläggningskostnaderna sänks med hjälp av nya tekniker. Community farms och institutionella odlingar prioriterar social hållbarhet medan kommersiella odlingar främst satsar på ekologisk och ekonomisk hållbarhet. Stadsodlingar är och har möjlighet att bli en allt viktigare del i matförsörjningen i städer. Då städerna förtätas minskar tillgänglig odlingsyta och andra lösningar måste användas. Byggnadsintegrerad stadsodling är en hållbar lösning både ekologiskt och socialt, och kan även kostnaderna för en byggnadsintegrerad odling minska kan dessa odlingar vara till stor hjälp för att minska svält och fattigdom. The world population is increasing at a rapid pace and city farms may be a way to provide food to the growing population. How building integrated urban farms, with a focus on roofs, can be linked to sustainability, is examined in this report. The current situation in Africa and North America are examined and the question to be answered is: How does the priority of the dimensions of sustainability vary at different conditions for urban building integrated farms in Africa and North America? The aspects of sustainability linked to building integrated urban farms are determined to be ecological, social and economic. Urban farms can also be divided into four different business types, of which institutional farms, commercial farms and community farms are analyzed. The results show that Africa and North America differ in possibilities for urban farming to be sustainable. Africa currently consists of 1.1 billion people, and this is expected to rise to 2.4 billion in 2050. Climate is dry in most places and a large part of the population lives in poverty and starvation. North America has a colder climate with four seasons, and the population will remain stable until 2050. North America is classified as a more developed area, which means that the economics in this area also are more developed than they are in Africa. There are more large-sized farms in North America than in Africa, and there are also more examples in North America. The conclusions are that building integrated urban cultures have a better potential to develop in North America since they require a large investment expense. For building integrated urban farms to be a more sustainable solution both in Africa and North America requirements are that construction costs need to be lowered. Community farms and institutional cultures prioritize social sustainability while commercial plantations mainly focus on ecological and economic sustainability. Urban farming is and may become an increasingly important part of the food supply in cities. When the cities densify it reduces available spaces for cultivation and other solutions must be used. These types of farms are sustainable solution both economic and social. If the cost of a building integrated farm can reduce these farms may help to reduce hunger and poverty.

Exercise and its effects on depression in young adults

Includes bibliographical references

Conformal Mapping and Bound States in Bent Waveguides

Is it possible to trap a quantum particle in an open geometry? In this work we deal with the boundary value problem of the stationary Schroedinger (or Helmholtz) equation within a waveguide with straight segments and a rectangular bending. The problem can be reduced to a one dimensional matrix Schroedinger equation using two descriptions: oblique modes and conformal coordinates. We use a corner-corrected WKB formalism to find the energies of the one dimensional problem. It is shown that the presence of bound states is an effect due to the boundary alone, with no classical counterpart for this geometry. The conformal description proves to be simpler, as the coupling of transversal modes is not essential in this case.Comment: 16 pages, 10 figures. To appear in the Proceedings of the Symposium "Symmetries in Nature, in memoriam Marcos Moshinsky

Fearless: Casey Butrico and Melanie Emerson

Casey Butrico (‘16) and Melanie Emerson (‘16) recently started a discussion group called Students for Reproductive Justice. This group is dedicated to the belief that women should control all aspects of their reproduction, including education about and access to safe birth control. They also aim to focus on gynecological care, pre-natal care, and abortion as human rights. These two fearless first-years have made a mission to educate and raise awareness about local and national issues that relate to women’s reproductive autonomy and the legal restrictions threatening it. [excerpt

Constitutive acoustic-emission elastic-stress behavior of magnesium alloy

Repeated laoding and unloading of a magnesium alloy below the macroscopic yield stress result in continuous acoustic emissions which are generally repeatable for a given specimen and which are reproducible between different specimens having the same load history. An acoustic emission Bauschinger strain model is proposed to describe the unloading emission behavior. For the limited range of stress examined, loading and unloading stress delays of the order of 50 MN/sq m are observed, and they appear to be dependent upon the direction of loading, the stress rate, and the stress history. The stress delay is hypothesized to be the manifestation of an effective friction stress. The existence of acoustic emission elastic stress constitutive relations is concluded, which provides support for a previously proposed concept for the monitoring of elastic stresses by acoustic emission

Convergence Conditions for Random Quantum Circuits

Efficient methods for generating pseudo-randomly distributed unitary operators are needed for the practical application of Haar distributed random operators in quantum communication and noise estimation protocols. We develop a theoretical framework for analyzing pseudo-random ensembles generated through a random circuit composition. We prove that the measure over random circuits converges exponentially (with increasing circuit length) to the uniform (Haar) measure on the unitary group and describe how the rate of convergence may be calculated for specific applications.Comment: 4 pages (revtex), comments welcome. v2: reference added, title changed; v3: published version, minor changes, references update

Parameterized Model-Checking for Timed-Systems with Conjunctive Guards (Extended Version)

In this work we extend the Emerson and Kahlon's cutoff theorems for process skeletons with conjunctive guards to Parameterized Networks of Timed Automata, i.e. systems obtained by an \emph{apriori} unknown number of Timed Automata instantiated from a finite set $U_1, \dots, U_n$ of Timed Automata templates. In this way we aim at giving a tool to universally verify software systems where an unknown number of software components (i.e. processes) interact with continuous time temporal constraints. It is often the case, indeed, that distributed algorithms show an heterogeneous nature, combining dynamic aspects with real-time aspects. In the paper we will also show how to model check a protocol that uses special variables storing identifiers of the participating processes (i.e. PIDs) in Timed Automata with conjunctive guards. This is non-trivial, since solutions to the parameterized verification problem often relies on the processes to be symmetric, i.e. indistinguishable. On the other side, many popular distributed algorithms make use of PIDs and thus cannot directly apply those solutions

NGC1333/IRAS4: A multiple star formation laboratory

We present SCUBA observations of the protomultiple system NGC1333/IRAS4 at 450um and 850um. The 850um map shows significant extended emission which is most probably a remnant of the initial cloud core. At 450um, the component 4A is seen to have an elongated shape suggestive of a disk. Also we confirm that in addition to the 4A and 4B system, there exists another component 4C, which appears to lie out of the plane of the system and of the extended emission. Deconvolution of the beam reveals a binary companion to IRAS4B. Simple considerations of binary dynamics suggest that this triple 4A-4BI-4BII system is unstable and will probably not survive in its current form. Thus IRAS4 provides evidence that systems can evolve from higher to lower multiplicity as they move towards the main sequence. We construct a map of spectral index from the two wavelengths, and comment on the implications of this for dust evolution and temperature differences across the map. There is evidence that in the region of component 4A the dust has evolved, probably by coagulating into larger or more complex grains. Furthermore, there is evidence from the spectral index maps that dust from this object is being entrained in its associated outflow.Comment: 10 pages, 10 figures. To appear in MNRAS. Uses mn.sty. Also available at http://www.astro.phys.ethz.ch/papers/smith/smith_p_m.htm