A generalized stoichiometric model of C3, C2, C2+C4, and C4 photosynthetic metabolism.

The goal of suppressing photorespiration in crops to maximize assimilation and yield is stimulating considerable interest among researchers looking to bioengineer carbon-concentrating mechanisms into C3 plants. However, detailed quantification of the biochemical activities in the bundle sheath is lacking. This work presents a general stoichiometric model for C3, C2, C2+C4, and C4 assimilation (SMA) in which energetics, metabolite traffic, and the different decarboxylating enzymes (NAD-dependent malic enzyme, NADP-dependent malic enzyme, or phosphoenolpyruvate carboxykinase) are explicitly included. The SMA can be used to refine experimental data analysis or formulate hypothetical scenarios, and is coded in a freely available Microsoft Excel workbook. The theoretical underpinnings and general model behaviour are analysed with a range of simulations, including (i) an analysis of C3, C2, C2+C4, and C4 in operational conditions; (ii) manipulating photorespiration in a C3 plant; (iii) progressively upregulating a C2 shuttle in C3 photosynthesis; (iv) progressively upregulating a C4 cycle in C2 photosynthesis; and (v) manipulating processes that are hypothesized to respond to transient environmental inputs. Results quantify the functional trade-offs, such as the electron transport needed to meet ATP/NADPH demand, as well as metabolite traffic, inherent to different subtypes. The SMA refines our understanding of the stoichiometry of photosynthesis, which is of paramount importance for basic and applied research

Aplikasi Perhitungan Pembiasan DC Pada Transistor Dwi Kutub NPN Dengan Visual Basic 6.0

Transistor dwi kutub (Bipolar Junction Transistor) adalah salah satu komponen semikonduktor yang sering digunakan dalam rangkaian penguat (amplifier). Untuk menjaga agar komponen ini dapat bekerja di dalam titik operasinya (operating point), maka diperlukan rangkaian pembiasan dengan pengaturan tertentu, yaitu Bias Basis, Bias Bagi Tegangan, Bias Kolektor dan Bias Emitter. Perancangan rangkaian tersebut lazimnya menggunakan perhitungan manual sesuai teori dengan bantuan alat hitung (kalkulator). Proses perancangan ini membutuhkan waktu yang relatif lama dan sangat rentan terjadi kesalahan prosedur perhitungan. Tujuan dari penelitian ini adalah merancang perangkat lunak perhitungan rangkaian pembiasan transistor dwi kutub dengan Visual Basic 6. Proses perancangan meliputi pembuatan form, pembuatan basis data (database), penulisan kode sumber (coding), desain laporan (report) dan kompilasi. Dari hasil uji coba diketahui bahwa tingkat kesalahan (error) untuk perhitungan seluruh parameter dari 4 jenis rangkaian pembiasan adalah 1,18%, sehingga disimpulkan layak digunakan. Hasil perhitungan juga dapat disajikan secara visual dalam rangkaian. Ditinjau dari sifat perangkat lunak ini sebagai aplikasi komputer, maka terdapat kelemahan dari sisi kepraktisan penggunaan, meski proses perhitungan dapat dilakukan relatif cepat. Selain itu, aplikasi ini masih memerlukan perbaikan dalam menu bantuan (help menu), penggunaan satuan dan faktor pengali.Transistor dwi kutub (Bipolar Junction Transistor) adalah salah satu komponen semikonduktor yang sering digunakan dalam rangkaian penguat (amplifier). Untuk menjaga agar komponen ini dapat bekerja di dalam titik operasinya (operating point), maka diperlukan rangkaian pembiasan dengan pengaturan tertentu, yaitu Bias Basis, Bias Bagi Tegangan, Bias Kolektor dan Bias Emitter. Perancangan rangkaian tersebut lazimnya menggunakan perhitungan manual sesuai teori dengan bantuan alat hitung (kalkulator). Proses perancangan ini membutuhkan waktu yang relatif lama dan sangat rentan terjadi kesalahan prosedur perhitungan. Tujuan dari penelitian ini adalah merancang perangkat lunak perhitungan rangkaian pembiasan transistor dwi kutub dengan Visual Basic 6. Proses perancangan meliputi pembuatan form, pembuatan basis data (database), penulisan kode sumber (coding), desain laporan (report) dan kompilasi. Dari hasil uji coba diketahui bahwa tingkat kesalahan (error) untuk perhitungan seluruh parameter dari 4 jenis rangkaian pembiasan adalah 1,18%, sehingga disimpulkan layak digunakan. Hasil perhitungan juga dapat disajikan secara visual dalam rangkaian. Ditinjau dari sifat perangkat lunak ini sebagai aplikasi komputer, maka terdapat kelemahan dari sisi kepraktisan penggunaan, meski proses perhitungan dapat dilakukan relatif cepat. Selain itu, aplikasi ini masih memerlukan perbaikan dalam menu bantuan (help menu), penggunaan satuan dan faktor pengali

Partial Covering Arrays: Algorithms and Asymptotics

A covering array $\mathsf{CA}(N;t,k,v)$ is an $N\times k$ array with entries in $\{1, 2, \ldots , v\}$, for which every $N\times t$ subarray contains each $t$-tuple of $\{1, 2, \ldots , v\}^t$ among its rows. Covering arrays find application in interaction testing, including software and hardware testing, advanced materials development, and biological systems. A central question is to determine or bound $\mathsf{CAN}(t,k,v)$, the minimum number $N$ of rows of a $\mathsf{CA}(N;t,k,v)$. The well known bound $\mathsf{CAN}(t,k,v)=O((t-1)v^t\log k)$ is not too far from being asymptotically optimal. Sensible relaxations of the covering requirement arise when (1) the set $\{1, 2, \ldots , v\}^t$ need only be contained among the rows of at least $(1-\epsilon)\binom{k}{t}$ of the $N\times t$ subarrays and (2) the rows of every $N\times t$ subarray need only contain a (large) subset of $\{1, 2, \ldots , v\}^t$. In this paper, using probabilistic methods, significant improvements on the covering array upper bound are established for both relaxations, and for the conjunction of the two. In each case, a randomized algorithm constructs such arrays in expected polynomial time

Triple intussusception involving heterotopic pancreatic tissue: a case report

<p>Abstract</p> <p>Introduction</p> <p>Intussusception involving heterotopic pancreatic tissue is a rare condition where a portion of the bowel telescopes into an adjacent segment with intraluminal pancreatic tissue as the lead point. Cases of heterotopic pancreas are most often described in the upper intestinal tract, particularly the stomach.</p> <p>Case presentation</p> <p>We present the case of a five-month-old boy of Caucasian ethnicity suffering acute abdominal pain and vomiting with an abdominal mass in the upper right quadrant. Work-up including ultrasound scan confirmed the intussusception. Repeated attempts at radiological reduction and two laparoscopic procedures were performed within 24 hours, which eventually led to the diagnosis of a triple intussusception.</p> <p>Conclusion</p> <p>To our knowledge, such a case of triple intussusception involving isolated heterotopic pancreatic tissue is previously unreported.</p

Two-dimensional amine and hydroxy functionalized fused aromatic covalent organic framework

Ordered two-dimensional covalent organic frameworks (COFs) have generally been synthesized using reversible reactions. It has been difficult to synthesize a similar degree of ordered COFs using irreversible reactions. Developing COFs with a fused aromatic ring system via an irreversible reaction is highly desirable but has remained a significant challenge. Here we demonstrate a COF that can be synthesized from organic building blocks via irreversible condensation (aromatization). The as-synthesized robust fused aromatic COF (F-COF) exhibits high crystallinity. Its lattice structure is characterized by scanning tunneling microscopy and X-ray diffraction pattern. Because of its fused aromatic ring system, the F-COF structure possesses high physiochemical stability, due to the absence of hydrolysable weak covalent bonds

Hidden Orbital Order in URu2Si2URu_{2}Si_{2}

When matter is cooled from high temperatures, collective instabilities develop amongst its constituent particles that lead to new kinds of order. An anomaly in the specific heat is a classic signature of this phenomenon. Usually the associated order is easily identified, but sometimes its nature remains elusive. The heavy fermion metal $URu_2Si_2$ is one such example, where the order responsible for the sharp specific heat anomaly at $T_0=17 K$ has remained unidentified despite more than seventeen years of effort. In $URu_{2}Si_{2}$, the coexistence of large electron-electron repulsion and antiferromagnetic fluctuations in $URu_2Si_2$ leads to an almost incompressible heavy electron fluid, where anisotropically paired quasiparticle states are energetically favored. In this paper we use these insights to develop a detailed proposal for the hidden order in $URu_2Si_2$. We show that incommensurate orbital antiferromagnetism, associated with circulating currents between the uranium ions, can account for the local fields and entropy loss observed at the $17 K$ transition; furthermore we make detailed predictions for neutron scattering measurements

New evidence on Allyn Young's style and influence as a teacher

This paper publishes the hitherto unpublished correspondence between Allyn Abbott Young's biographer Charles Blitch and 17 of Young's former students or associates. Together with related biographical and archival material, the paper shows the way in which this adds to our knowledge of Young's considerable influence as a teacher upon some of the twentieth century's greatest economists. The correspondents are as follows: James W Angell, Colin Clark, Arthur H Cole, Lauchlin Currie, Melvin G de Chazeau, Eleanor Lansing Dulles, Howard S Ellis, Frank W Fetter, Earl J Hamilton, Seymour S Harris, Richard S Howey, Nicholas Kaldor, Melvin M Knight, Bertil Ohlin, Geoffrey Shepherd, Overton H Taylor, and Gilbert Walker

Noncommutative Vortices and Instantons from Generalized Bose Operators

Generalized Bose operators correspond to reducible representations of the harmonic oscillator algebra. We demonstrate their relevance in the construction of topologically non-trivial solutions in noncommutative gauge theories, focusing our attention to flux tubes, vortices, and instantons. Our method provides a simple new relation between the topological charge and the number of times the basic irreducible representation occurs in the reducible representation underlying the generalized Bose operator. When used in conjunction with the noncommutative ADHM construction, we find that these new instantons are in general not unitarily equivalent to the ones currently known in literature.Comment: 25 page

Spin-orbit density wave induced hidden topological order in URu2Si2

The conventional order parameters in quantum matters are often characterized by 'spontaneous' broken symmetries. However, sometimes the broken symmetries may blend with the invariant symmetries to lead to mysterious emergent phases. The heavy fermion metal URu2Si2 is one such example, where the order parameter responsible for a second-order phase transition at Th = 17.5 K has remained a long-standing mystery. Here we propose via ab-initio calculation and effective model that a novel spin-orbit density wave in the f-states is responsible for the hidden-order phase in URu2Si2. The staggered spin-orbit order 'spontaneous' breaks rotational, and translational symmetries while time-reversal symmetry remains intact. Thus it is immune to pressure, but can be destroyed by magnetic field even at T = 0 K, that means at a quantum critical point. We compute topological index of the order parameter to show that the hidden order is topologically invariant. Finally, some verifiable predictions are presented.Comment: (v2) Substantially modified from v1, more calculation and comparison with experiments are include