One of the most difficult problems in mining operation is how to determine optimum cut-off grades of ores at different periods over the lifespan of the mine that will maximize the net present value (NPV) of the mine. Maximizing the NPV of a mining operation, subject to different constraints is a nonlinear programming problem. Cut-off grade optimization is used to arrive at an operating strategy...

The purpose of this research are (1) Find out the control limits implementation quality on PT.Perkebunan Nusantara VIII Kebun Kertamanah. (2) to determine production low black tea products under controlled conditions in (3) factors that cause not meet standards (4) find percentage value off grade basic method is descriptive with case study. Data were analyzed using check sheet p chart fishbone ...

BACKGROUND The abbreviated Alcohol Use Disorder Identification Test for Consumption (AUDIT-C) is rapidly becoming the alcohol screening tool of choice for busy practitioners in clinical settings and by researchers keen to limit assessment burden and reactivity. Cut-off scores for detecting drinking above recommended limits vary by population, setting, country and potentially format. This valida...

The hydrologic cycle results from the combination of energy conversions and atmospheric transport, and the laws of thermodynamics set limits to both. Here, we apply thermodynamics to derive the limits of the strength of hydrologic cycling within the Earth system and about the properties and processes that shape these limits. We set up simple models to derive analytical expressions of the limits...

Governments are present-biased toward spending. Fiscal rules are deficit limits that trade off commitment to not overspend and flexibility to react to shocks. We compare centralized rules — chosen jointly by all countries — to decentralized rules. If governments’ present bias is small, centralized rules are tighter than decentralized rules: individual countries do not internalize the redistribu...

We review the construction of exactly solvable lattice models whose continuum limits are N = 2 supersymmetric models. Both critical and off-critical models are discussed. The approach we take is to first find lattice models with natural topological sectors, and then identify the continuum limits of these sectors with topologically twisted N = 2 supersymmetric field theories. From this, we then ...

Soil and plant hydraulics constrain ecosystem productivity by setting physical limits to water transport and hence carbon uptake by leaves. While more negative xylem water potentials provide a larger driving force for water transport, they also cause cavitation that limits hydraulic conductivity. An optimum balance between driving force and cavitation occurs at intermediate water potentials, th...

Evolutionary biologists increasingly recognize that evolution can be constrained by trade-offs, yet our understanding of how and when such constraints are manifested and whether they restrict adaptive divergence in populations remains limited. Here, we show that spatial heterogeneity in moisture maintains a polymorphism for pungency (heat) among natural populations of wild chilies (Capsicum cha...