Abstract:
mulches bring several benefits to lettuce cultivation. this work evaluated the effect of mulches on the cultivation of iceberg lettuce, cv. lucy brown. the treatment plots were: 1- no mulch and no weed control (control); 2- no mulch and weed control every 15 days; 3- sugarcane bagasse mulch of 2 cm thickness; 4- black plastic mulch; 5- double-faced plastic mulch (silver/black). data were collected in regard to plant cycle when in the field, amount of chlorophyll in the leaves, productivity (individual weight per head) and amount of nutrients absorbed by the leaves. double-faced plastic mulch provides the highest productivity and the highest values for the amount of chlorophyll, nitrogen, phosphorus, sulfur, boron and iron accumulation in the leaves.

Abstract:
Mulches bring several benefits to lettuce cultivation. This work evaluated the effect of mulches on the cultivation of iceberg lettuce, cv. Lucy Brown. The treatment plots were: 1- no mulch and no weed control (control); 2- no mulch and weed control every 15 days; 3- sugarcane bagasse mulch of 2 cm thickness; 4- black plastic mulch; 5- double-faced plastic mulch (silver/black). Data were collected in regard to plant cycle when in the field, amount of chlorophyll in the leaves, productivity (individual weight per head) and amount of nutrients absorbed by the leaves. Double-faced plastic mulch provides the highest productivity and the highest values for the amount of chlorophyll, nitrogen, phosphorus, sulfur, boron and iron accumulation in the leaves.

Abstract:
Iceberg Cube is meaningful for OLAP (on-line analysis processing) and compression techniques play more and more important role in reducing the storage of data warehouse and improving the efficiency of data operations. It is really a problem to compute Iceberg Cube efficiently in the compressed data warehouse. The compression techniques of data warehouse are introduced concisely in this paper, and an algorithm to compute Iceberg Cube in compressed data warehouse by mapping-complete methods is proposed. Experimental results show that this algorithm outperforms the direct method that selects Iceberg Cube tuples from the complete computed cube.

Abstract:
The symbolic complexity of an infinite word $W$ is the function $p_W(l)$ counting the number of different subwords in $W$ of length $l$. In this paper our main purpose is to study the complexity for a class of topological dynamical systems, called iceberg systems, given by the following symbolic procedure. Starting from a given finite word $w_1$ we construct a sequence of words $w_{n+1} = w_n \rho_{a_n(1)}(w_n)...\rho_{a_n(q_n-1)}(w_n)$, where $\rho_a(u)$ is the cyclic rotations of the word $u$ by $a$ positions, and consider an infinite word $W$ extending each $w_n$ to the right. It is shown that for iceberg systems given by the randomized parameters $a_n(j)$ the complexity function almost surely satisfies the estimate $p_W(l) > l^{3-\epsilon}$ for any $\epsilon > 0$ and $l \ge l_0(\epsilon)$, and at the same time it is observed that this estimate represents up to a small correction the optimal lower bound for the complexity function, namely, $p_{w_{n+1}}(l_n) \le l_n^3$ along the subsequence $l_n = |w_n|+1$.

Abstract:
We investigate a class of mixing dynamical systems around the concept of iceberg transformation. In brief, an iceberg transformation is defined using symbolic language as follows. We build a sequence of words such that the next word is a concatenation of rotated copies of the previous word. For example, a word CAT can turn into CAT.ATC.TCA.TCA.CAT.ATC, then we repeat the procedure applying it to this new word and so on. Geometrically, given an invertible measure preserving transformation $T$ an iceberg is a union of two icelets for the map $T$, one direct and one reverse with common base set, where icelet is defined in a similar way as Rokhlin tower $B \sqcup TB \sqcup \ldots \sqcup T^{h-1}B$, namely, an icelet is a sequence of disjoint measurable sets $\{B_0, B_1, \ldots, B_{h-1}\}$ such that the levels are nested: $B_{j+1} \subseteq TB_j$. Reverse icelet is defined as icelet for $T^{-1}$, and it grows towards the past. Iceberg transformation is approximated by a sequence of icebergs, resembling the behaviour of rank one ergodic maps. It is show that a class of random iceberg transformations almost surely has simple spectrum, $1/4$-local rank property and spectral type $\sigma$ such that $\sigma \conv \sigma \ll \la$ where $\la$ is the Lebesgue measure on the circle $S^1$.

Abstract:
Johne's disease (JD) is a chronic, enteric disease in ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). Disease progression follows four distinct stages: silent, subclinical, clinical and advanced. Available diagnostic tests have poor sensitivity and cannot detect early stages of the infection; as a result, only animals in the clinical and advanced stages, which represent the tip of the ‘iceberg’, are identified through testing. The Iceberg Phenomenon is then applied to provide estimates for JD prevalence. For one animal in the advanced stage, it is assumed that there are one to two in the clinical stage, four to eight in the subclinical stage, and ten to fourteen in the silent stage. These ratios, however, are based on little evidence. To evaluate the ratios, we developed a deterministic ordinary differential equation model of JD transmission and disease progression dynamics. When duration periods associated with the natural course of the disease progression are used, the above ratios do not hold. The ratios used to estimate JD prevalence need to be further investigated.