No Double Discount: Condition-based Simultaneity Yields Limited Gain

Assuming each process proposes a value, the consensus problem requires the non-faulty processes to agree on the same value that has to be a proposed value. Solutions to the consensus problem in synchronous systems are based on the round-based model, namely, the progress of the processes is according to synchronous rounds. Simultaneous consensus requires that the non-faulty processes decide not only on the same value, but decide during the very same round. It has been shown by Dwork and Moses that, in a synchronous system prone to t process crashes, the earliest round at which a common decision can be simultaneously obtained is (t+1)-D where D is a non-negative integer determined by the actual failure pattern F. The condition-based approach to solve consensus assumes that the input vector belongs to set C (a set of input vectors satisfying a property called legality). Interestingly, the conditions for synchronou s consensus define a hierarchy of sets of conditions. It has been shown that d+1 is a tight lower bound on the minimal number of rounds for synchronous condition-based consensus (where d characterizes the class of constions the algorithm is instantiated with). This paper considers the synchronous condition-based consensus problem with simultaneous decision. It first presents a simple algorithm that directs the processes to decide simultaneously at the end of the round RS(t,d,F)=min((t+1)-D, d+1) (i.e., RS(t,d,F)=(t+1)-max(D,delta) with delta=t-d). The paper then shows that RS(t,d,F)is a lower bound for the condition-based simultaneous consensus problem. It thus follows that the algorithm designed is optimal in each and every run, and not just in the worst case: For every choice of failure pattern by the adversary (and every input configuration), the algorithm reaches simultaneous as fast as any correct algorithm could do under the same conditions. This shows that, contrary to what could be hoped, when considering condition-based consensus with simultaneous decision, we can benefit from the best of both actual worlds (either the failure world when RS(t,d,F)=(t+1)-D, or the condition world when RS(t,d,F)=d+1), but we cannot benefit from the sum of savings offered by both. Only one discount applies

An Optimal Self-Stabilizing Firing Squad

Consider a fully connected network where up to $t$ processes may crash, and all processes start in an arbitrary memory state. The self-stabilizing firing squad problem consists of eventually guaranteeing simultaneous response to an external input. This is modeled by requiring that the non-crashed processes "fire" simultaneously if some correct process received an external "GO" input, and that they only fire as a response to some process receiving such an input. This paper presents FireAlg, the first self-stabilizing firing squad algorithm. The FireAlg algorithm is optimal in two respects: (a) Once the algorithm is in a safe state, it fires in response to a GO input as fast as any other algorithm does, and (b) Starting from an arbitrary state, it converges to a safe state as fast as any other algorithm does.Comment: Shorter version to appear in SSS0

Emerging Physico-Chemical Methods for Biomass Pretreatment

A major challenge to commercial production of cellulosic ethanol pertains to the cost-effective breakdown of the complex and recalcitrant structure of lignocellulose into its components by pretreatment methods—physical, chemical, physico-chemical, biological and various combinations thereof. The type and conditions of a pretreatment impacts both upstream processes such as size reduction as well as downstream processes such as enzymatic hydrolysis and enzyme loadings, and as such the choice of a pretreatment method for a specific biomass (or mix of materials) is influenced by several factors such as carbohydrate preservation and digestibility, sugar and ethanol yields, energy consumption, equipment and solvent costs, lignin removal and quality, formation of sugar/lignin degradation products, waste production, and water usage, among others. This chapter reviews both well-known and emerging physico-chemical methods of biomass fractionation with regards to process description and applications, advantages and disadvantages, as well as recent innovations employed to improve sugar yields, environmental sustainability and process economics

Evaluation of the Phytoplanktons Species Diversity, Distribution and Physicochemical Characteristics of Pindiga Pond in Gombe State of Nigeria

Studies were conducted on the diversity, distribution and physicochemical characteristics of phytoplanktons of Pindiga Pond. Water and phytoplankton samples were collected for three months at ten (10) days interval. The objective of the present research is to determine the phytoplanktons distribution and physicochemical characteristics of the Pond. Standard procedures were adopted for determination of physicochemical parameters viz; Temperature, pH, Transparency, Conductivity, Nitrate, Phosphate, Dissolved oxygen (DO), Biological Oxygen Demand (BOD).These physicochemical characteristics were observed to have varied within the period of the study. Seventeen (17) genus, Thirteen (13) orders, four (4) classes, and four (4) division of phytoplankton were identified, and the class Bacillariophyceae (46 %) was the highest percentage recorded during the study, Chlorophyceae (32 %), Euglenophyceae (19 %) and Cyanophyceae (3%) the least in occurrence and distribution. The study also revealed that pindiga pond had luxuriant phytoplanktons flora, diverse and seasonal with fluctuating pattern of physicochemical characteristics recorded. The physicochemical characteristics were also within productive limit in Pindiga pond.Key words: Phytoplanktons, Diversity, Distribution, Pon

Analisis Akses Keuangan dan Pengembangan Usaha Mikro di Wilayah Perbatasan RI-PNG

Tujuan dari kajian ini adalah mengetahui kontribusi LKM dan UMKM terhadap tingkat kesejahtaraan masyarakat maupun perkembangan LKM dan UMKM di Wilayah Perbatasan RI- PNG, secara umum maupun secara khusus bagi masyarakat asli Papua. Dari kajian ini dirumuskan model pengembangan UMKM di wialayah perbatasan antar negara, sebagai pusat pertumbuhan ekonomi yang berkelanjutan, sehingga dapat meningkatkan kesejahteraan masyarakat lokal dan semua pelaku USAha di wialayah perbatasan. Adapun masalah umum yang dihadapi di kawasan perbatasan, antara lain adalah: (1) Belum adanya lembaga keuangan yang berada di wilayah perbatasan antara RI P-PNG hal ini mempegaruhi tingkat akses permodalan dan perkembangan UMKM; (2) Sebagian besar UMKM Asli Papua tidak memanfaatkan peluang Pasar Perbatasan secara baik. Dari hasil kajian potensi USAha di wialyah perbatasan sagat menjanjikan, baik potensi perdangan,potensi pariwisatan dan adanya peluang pengembangan USAha-USAha baru. Hasil kajian ini diharapkan dapat berkontribusi untuk peningkatan kesejahteraan rakyat Papua melalui Perumusan, implementasi, dan pengembangan konsep keuangan mikro yang bernuansa (spesifik) Papua, efisien dan efektif diwilayah ini. Berdasarkan hasil kaji, maka perlu adanya LKM yang dapat beropersi di Wilayah Perbatasan, perlu adanya regulasi khusus bagi wilayah perbatasan dan UMKM asli Papua perlu pendampingan dalam hal pengembangan USAha agar mampu bersaing diwilayah Perbatasan

Absence of supersolidity in solid helium in porous Vycor glass

In 2004, Kim and Chan (KC) carried out torsional oscillator (TO) measurements of solid helium confined in porous Vycor glass and found an abrupt drop in the resonant period below 200 mK. The period drop was interpreted as probable experimental evidence of nonclassical rotational inertia (NCRI). This experiment sparked considerable activities in the studies of superfluidity in solid helium. More recent ultrasound and TO studies, however, found evidence that shear modulus stiffening is responsible for at least a fraction of the period drop found in bulk solid helium samples. The experimental configuration of KC makes it unavoidable to have a small amount of bulk solid inside the torsion cell containing the Vycor disc. We report here the results of a new helium in Vycor experiment with a design that is completely free from any bulk solid shear modulus stiffening effect. We found no measureable period drop that can be attributed to NCRI