97,781 research outputs found

    The comfort zone: Reflection on a taken-for-granted model

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    Reference to the comfort zone model is widespread within outdoor adventure education. It is based on the belief that when placed in a stressful situation people will respond by overcoming their hesitancy and grow. This model is often presented to students prior to activities with a perceived sense of risk and challenge which arouses strong emotional and physical responses to novel tasks (e.g., a ropes course). Students are encouraged to ‘stretch themselves’, to move outside their comfort zone and expand their preconceived limits and by inference learn. This article briefly explores the theories that underpin the comfort zone model and suggests that it is time to rethink how it is used

    Convex Integer Optimization by Constantly Many Linear Counterparts

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    In this article we study convex integer maximization problems with composite objective functions of the form f(Wx)f(Wx), where ff is a convex function on Rd\R^d and WW is a d×nd\times n matrix with small or binary entries, over finite sets SZnS\subset \Z^n of integer points presented by an oracle or by linear inequalities. Continuing the line of research advanced by Uri Rothblum and his colleagues on edge-directions, we introduce here the notion of {\em edge complexity} of SS, and use it to establish polynomial and constant upper bounds on the number of vertices of the projection \conv(WS) and on the number of linear optimization counterparts needed to solve the above convex problem. Two typical consequences are the following. First, for any dd, there is a constant m(d)m(d) such that the maximum number of vertices of the projection of any matroid S{0,1}nS\subset\{0,1\}^n by any binary d×nd\times n matrix WW is m(d)m(d) regardless of nn and SS; and the convex matroid problem reduces to m(d)m(d) greedily solvable linear counterparts. In particular, m(2)=8m(2)=8. Second, for any d,l,md,l,m, there is a constant t(d;l,m)t(d;l,m) such that the maximum number of vertices of the projection of any three-index l×m×nl\times m\times n transportation polytope for any nn by any binary d×(l×m×n)d\times(l\times m\times n) matrix WW is t(d;l,m)t(d;l,m); and the convex three-index transportation problem reduces to t(d;l,m)t(d;l,m) linear counterparts solvable in polynomial time

    Habsburške deželnoknežje posesti v notranjosti Istre v luči obračunov iz leta 1439

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    Leta 1435 je potekla zastava zemljiških gospostev, ki sta jih avstrijska vojvoda Leopold in Ernest februarja in marca 1407 prepustila Reinprechtu II. Walseejskemu kot odškodnino za dolg v višini 32.000 dukatov, med njimi tudi precejšen del centralne Istre obsegajoča Pazinska grofija, ki so jo Habsburžani prejeli leta 1374 z dedovanjem po istrski veji goriških grofov. Prav iz začetka tega obdobja, iz leta 1439 se je ohranila knjiga letnih obračunov habsburških zemljiških gospostev, katere obračuni za gospostva Pazin, Vranja in Završje predstavljajo najstarejši administrativni vir za to ozemlje in nudijo vpogled v upravo in poslovanje z zemljiško posestjo. Gospodarski potencial habsburške komorne posesti v Pazinski grofiji, kot jo dokumentirajo obračuni s konca tridesetih let 15. stoletja, je temeljil predvsem na kmetijski proizvodnji. Med prihodki gospostva so imeli največji pomen vino, žito (predvsem pšenica, rž in oves), drobnica in sir. Celotni letni prihodki habsburške komorne posesti v Istri v letih 1437-1438, so znašali 620 mark 38 soldov, od tega je odpadlo na pazinsko gospostvo 451 m 154 ß, na završko 123 m 96 ß in na vranjsko 46 m 108 ß. Temu nasproti obračuni postavljajo letne izdatke – ki se nanašajo predvsem na plače uradnikov in gradbeno-vzdrževalna dela – v skupni višini 215 m 6 ß; od tega v pazinskem gospostvu 130 m 111 ß, v Vranji 32 m 153 ß in v Završju 51 m 62 ß. Bilanca obravnavanih obračunov kaže okvirni letni dohodek okoli 400 mark beneških soldov, ki so ga Habsburžanom prinašala istrska komorna gospostva, kar – za primerjavo – ustreza približno 10% deležu celotnega habsburškega komornega dohodka na Kranjskem in v Istri
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