Free Energy Evaluation Using Marginalized Annealed Importance Sampling

The evaluation of the free energy of a stochastic model is considered to be a significant issue in various fields of physics and machine learning. However, the exact free energy evaluation is computationally infeasible because it includes an intractable partition function. Annealed importance sampling (AIS) is a type of importance sampling based on the Markov chain Monte Carlo method, which is similar to a simulated annealing, and can effectively approximate the free energy. This study proposes a new AIS-based approach, referred to as marginalized AIS (mAIS). The statistical efficiency of mAIS is investigated in detail based on a theoretical and numerical perspectives. Based on the investigation, it has been proved that mAIS is more effective than AIS under a certain condition

Innate immune response to subacute ruminal acidosis in beef cattle

Background: Subacute ruminal acidosis (SARA) is a metabolic disease that affects both dairy and beef cattle. The effects of SARA have been extensively studied in dairy cattle, but information in beef cattle is limited. Grain-induced subacute ruminal acidosis is associated with systemic inflammation in both beef and dairy cattle. The insidious nature of SARA, coupled with lack of specific signs means that the condition is quite difficult to diagnose in beef cattle.Hypotheses: SARA occurs naturally in beef cattle that are undergoing preconditioning at a backgrounding facility. SARA causes ruminal bacteria population changes coupled with increase in levels of free endotoxin and biogenic amines in the rumen. The ruminal changes are associated with increased levels of endotoxin and increased expression of inflammatory cytokine in broncho-alveolar lavage (BALF) and blood.Materials and Methods: Rumenocentesis was performed to evaluate the occurrence of SARA in cattle being fed preconditioning diets. Ruminal fluid pH was also measured in animals that were identified as having bovine respiratory disease. Ruminal bacteria population changes were evaluated using qRT-PCR. Endotoxin concentration in ruminal fluid and plasma was quantified using a kinetic chromogenic Limulus Amoebocyte Lysate test. The expression inflammatory cytokines in BALF and blood was assessed with qRT-PCR. An HPLC method was developed to quantify biogenic amines in ruminal fluid.Results: Rumenocentesis was performed without complications. Thirteen out of sixty (22%) cattle had ruminal pH less than or equal to 5.6 on day 21 in one the studies. Lactate-utilizing Gram negative bacteria, Megasphaera elsdenii was significantly up-regulated in groups of animals being fed high amounts of fermentable carbohydrates. Ruminal fluid and plasma endotoxin concentration increased with time in animals being fed varying amounts of highly fermentable carbohydrates. The concentration of endotoxin was correlated with the quantity of highly fermentable carbohydrates in the diet. The concentration of biogenic amines was higher in animals receiving higher amounts of highly fermentable carbohydrates. Pro-inflammatory cytokine were upregulated in both ruminal fluid and blood for the first two weeks. On the third week, IL-1B; and TNF were down-regulated.Conclusion: The innate immune response to SARA resembles endotoxin tolerance. Endotoxin tolerance needs further investigation in cattle

Outcomes of reconstructive surgery of tuberculosis affecting the ureter and bladder

Background: Genito-urinary tuberculosis (GUTB) affects kidneys and bladder more frequently leading to scarring and eventually loss of function. Reconstructive surgical procedures are implemented to preserve the function by relieving obstruction of the urinary tract. The main objective of this study was to evaluate the outcome of urinary reconstructive surgical procedures in terms of improvement in renal function and quality of life.Methods: This was retrospective analysis of all patients treated for tuberculous stricture of the ureter and scarring of the bladder from January 2001 to December 2005. Outcome of interventions were assessed using IVU, TC-DTPA renogram and serum creatinine level.Results: Among the 160 genito-urinary tuberculosis cases diagnosed in the 5 year period, only 51 patients fulfilled the inclusion criteria and were managed with reconstructive surgery alone or in combination with temporary diversion. Sixteen (31.5%) patients had elevated serum creatinine level greater than 1.5mg% out of which Nadir serum creatinine level less than 1.5mg% was found in only 9 patients following various procedures. Pan urethral or multiple segment involvement occurred in 24 ureters of which 10 required eventual definitive reconstructive surgery. Twenty eight bladders were found scarred of which 17 needed augmentation procedures.Conclusions: Based on acceptable renal function using Tc-scan, renogram and other functional assessments an overall favourable outcome of 92% at median follow up of 18 (6-48) months was observed

Synthesis of aminomethylphenol derivatives via magnetic nano Fe3O4 catalyzed one pot Petasis borono-Mannich reaction

A novel library of aminomethylphenol has been developed using magnetic Fe3O4 nanoparticles via Petasis borono-Mannich reaction of salicylaldehydes, secondary amines and phenyl boronic acids. This one-pot protocol features mild reaction conditions, excellent yields in short reaction times, readily available starting materials, good functional group tolerance and reusability of the catalyst for four consecutive cycles without significant loss in its activity

How Polygenetic are Monogenetic Volcanoes: Case Studies of Some Complex Maar‐Diatreme Volcanoes

The increasing number of field investigations and various controlled benchtop and large‐scale experiments have permitted the evaluation of a large number of processes involved in the formation of maar‐diatreme volcanoes, the second most common type of small‐volume subaerial volcanoes on Earth. A maar‐diatreme volcano is recognized by a volcanic crater that is cut into country rocks and surrounded by a low‐height ejecta rim composed of pyroclastic deposits of few meters to up to 200 m thick above the syn‐eruptive surface level. The craters vary from 0.1 km to up to 5 km wide and vary in depth from a few dozen meters to up to 300 m deep. Their irregular morphology reflects the simple or complex volcanic and cratering processes involved in their formation. The simplicity or complexity of the crater or the entire maar itself is usually observed in the stratigraphy of the surrounding ejecta rings. The latter are composed of sequences of successive alternating and contrastingly bedded phreatomagmatic‐derived dilute pyroclastic density currents (PDC) and fallout depositions, with occasional interbedded Strombolian‐derived spatter materials or scoria fall units, exemplifying the changes in the eruptive styles during the formation of the volcano. The entire stratigraphic sequence might be preserved as a single eruptive package (small or very thick) in which there is no stratigraphic gap or significant discordance indicative of a potential break during the eruption. A maar with a single eruptive deposit is quantified as monogenetic maar, meaning that it was formed by a single eruptive vent from which only a small and ephemeral magma erupted over a short period of time. The stratigraphy may also display several packages of deposits separated either by contrasting discordance surfaces or paleosoils, which reflect multiple phases or episodes of eruptions within the same maar. Such maars are characterized as complex polycyclic maars if the length of time between the eruptive events is relatively short (days to years). For greater length of time (thousands to millions of years), the complex maar will be quantified as polygenetic. These common depositional breaks interpreted as signs of temporal interruption of the eruptions for various timescales also indicate deep magma system processes; hence magmas of different types might erupt during the formation of both simple and complex maars. The feeding dikes can interact with groundwater and form closely distributed small craters. The latter can coalesce to form a final crater with various shapes depending on the distance between them. This observation indicates the significant role of the magmatic plumbing system on the formation and growth of complex and polygenetic maar‐diatreme volcanoes

An Investigation and Intervention on Challenges Faced by Natural Science Teachers When Conducting Practical Work in Three Selected School of Zambezi Region in Namibia

Practical work in science is acknowledged and widely accepted as an important component in teaching and learning. However, in the Zambezi region, it has been discovered that some primary schools find it difficult to engage their learners in practical work. As a result, only a little or no practical work is conducted in some primary schools. The aim of this study is to investigate the challenges faced by teachers in conducting practical work in selected primary schools in the Zambezi region. Interviews were conducted with Natural Science teachers in three selected primary schools in the rural areas to identify the challenges that they experienced in doing practical work in their lessons.  According to the data obtained from the participants, the results indicated that teachers faced challenges in conducting practical work in Natural science as there was: lack of apparatus and science laboratories, no time allocated for practical work on the school time-table and limited training on changes taking place in the education system. If the above challenges are to be taken care of, teachers will be able to do practical work effectively thus enhancing the performance of the learners and subsequently improving their results in Natural Science