Foreign institutional investors and security returns: evidence from Indian stock exchanges

India liberalized its financial markets by opening its doors to foreign institutional investors in September, 1992. We study this landmark event, by examining the impact of trading of Foreign Institutional Investors on the major stock indices of India. First, we find that unexpected flows have a greater impact than expected flows on stock indices. Second, we find strong evidence consistent with the base-broadening hypothesis. Third, we do not find any evidence that foreign institutional investors employ either momentum or contrarian strategies. Fourth, our findings support the price pressure hypothesis. Finally, the claim that foreigners’ destabilize the market is not substantiated. Keywords

Precoding by Pairing Subchannels to Increase MIMO Capacity with Discrete Input Alphabets

We consider Gaussian multiple-input multiple-output (MIMO) channels with discrete input alphabets. We propose a non-diagonal precoder based on the X-Codes in \cite{Xcodes_paper} to increase the mutual information. The MIMO channel is transformed into a set of parallel subchannels using Singular Value Decomposition (SVD) and X-Codes are then used to pair the subchannels. X-Codes are fully characterized by the pairings and a $2\times 2$ real rotation matrix for each pair (parameterized with a single angle). This precoding structure enables us to express the total mutual information as a sum of the mutual information of all the pairs. The problem of finding the optimal precoder with the above structure, which maximizes the total mutual information, is solved by {\em i}) optimizing the rotation angle and the power allocation within each pair and {\em ii}) finding the optimal pairing and power allocation among the pairs. It is shown that the mutual information achieved with the proposed pairing scheme is very close to that achieved with the optimal precoder by Cruz {\em et al.}, and is significantly better than Mercury/waterfilling strategy by Lozano {\em et al.}. Our approach greatly simplifies both the precoder optimization and the detection complexity, making it suitable for practical applications.Comment: submitted to IEEE Transactions on Information Theor

Modulation Diversity in Fading Channels with Quantized Receiver

In this paper, we address the design of codes which achieve modulation diversity in block fading single-input single-output (SISO) channels with signal quantization at receiver and low-complexity decoding. With an unquantized receiver, coding based on algebraic rotations is known to achieve modulation coding diversity. On the other hand, with a quantized receiver, algebraic rotations may not guarantee diversity. Through analysis, we propose specific rotations which result in the codewords having equidistant component-wise projections. We show that the proposed coding scheme achieves maximum modulation diversity with a low-complexity minimum distance decoder and perfect channel knowledge. Relaxing the perfect channel knowledge assumption we propose a novel training/estimation and receiver control technique to estimate the channel. We show that our coding/training/estimation scheme and minimum distance decoding achieve an error probability performance similar to that achieved with perfect channel knowledge

Architecture of eukaryotic mRNA 3' end processing machinery and insights into the mechanism of polyadenylation

Almost all eukaryotic messenger RNAs (mRNAs) have a polyadenosine (polyA) tail at their 3′ end that is added by a multi-protein complex known as cleavage and polyadenylation factor (CPF). CPF, along with accessory cleavage factors (CF) IA and IB, cleaves the pre-mRNA within the 3' untranslated region (UTR) and adds a poly(A) tail. Previous work has shown that CPF is a fourteen-subunit complex that is organised into three enzymatic modules: phosphatase, nuclease and polymerase. The polymerase module consists of the poly(A) polymerase Pap1, three RNA binding proteins (Cft1, Pfs2 and Yth1) and an unstructured protein Fip1. To understand how polymerase module recognizes specific RNA elements and how polyA tail addition is coordinated with other factors, I recombinantly expressed and purified a five-subunit polymerase module. Electron cryomicroscopy analysis resulted in a 3.5 Å resolution structure of Cft1-Pfs2-Yth1, revealing four β propellers in an arrangement reminiscent of other nucleic acid binding complexes. Using biochemical assays, I show that CF IA stimulates polyadenylation activity of CPF by interacting with polymerase module and tethering it to substrate RNA. Thus polymerase module acts as a hub to bring together the RNA, Pap1 and cleavage factors for specific and efficient polyadenylation. The poly(A) tail length of newly made pre-mRNAs in S. cerevisiae is ~ 60 As. The nuclear poly(A) binding protein Nab2 is known to have a role in poly(A) tail length control. The molecular mechanism behind how CPF terminates polyadenylation to regulate uniform poly(A) tail length remains elusive. Using an in vitro polyadenylation assay with highly pure protein complexes, I have studied the mechanism of poly(A) tail length control by CPF. The assays highlight the contribution of the cleavage factors and the phosphatase module of CPF towards regulating the poly(A) tail length of a substrate RNA. Taken together, the findings discussed in this dissertation provide new insights into the architecture of eukaryotic mRNA 3' end processing machinery and into the mechanism of polyadenylation by CPF.GATES Cambridg

Dynein dynamics during meiotic nuclear oscillations of fission yeast

Cytoplasmic dynein is a ubiquitous minus-end directed motor protein that is essential for a variety of cellular processes ranging from cargo transport to spindle and chromosome positioning. Specifically, in fission yeast during meiotic prophase, the fused nucleus follows the spindle pole body in oscillatory movements from one cell pole to the other. The three molecular players that are essential to this process are: (i) the motor protein dynein, which powers the movement of the nucleus, (ii) microtubules, which provide the tracts for the movement and (iii) Num1, the anchor protein of dynein at the cortex. Dyneins that are localized to the anchor protein at the cortex and simultaneously bound to the microtubule emanating from the spindle pole body, pull on that microtubule leading to the movement of the nucleus. The spindle pole body, by virtue of its movement establishes a leading and a trailing side. Previous work by Vogel et al. has elucidated the mechanism of these oscillations as that of asymmetric distribution of dynein between the leading and trailing sides. This differential distribution is a result of the load-dependent detachment of dynein preferentially from the trailing microtubules. This self-organization model for dynein, however, requires a continuous redistribution of dynein from the trailing to the leading side. In addition, dyneins need to be bound to the anchor protein to be able to produce force on the microtubules. Anchored dyneins are responsible for many other important processes in the cell such as spindle alignment and orientation, spindle separation and rotation. So we set out to elucidate the mechanism of redistribution of dynein as well as the targeting mechanism of dynein from the cytoplasm to cortical anchoring sites where they can produce pulling force on microtubules. By employing single-molecule observation using highly inclined laminated optical sheet (HILO) microscopy and tracking of fluorescently-tagged dyneins using a custom software, we were able to show that dyneins redistributed in the cytoplasm of fission yeast by simple diffusion. We also observed that dynein bound first to the microtubule and not directly to the anchor protein Num1. In addition, we were able to capture unbinding events of single dyneins from the microtubule to the cytoplasm. Surprisingly, dynein bound to the microtubule exhibited diffusive behaviour. The switch from diffusive to directed movement required to power nuclear oscillations occurred when dynein bound to its cortical anchor Num1. In summary, dynein employs a two-step targeting mechanism from the cytoplasm to the cortical anchoring sites, with the attachment to the microtubule acting as the intermediate step

A Cartesian Space Approach to Teleoperate a Slave Robot with a Kinematically Dissimilar Redundant Manipulator

Due to the inability of humans to interact with certain unstructured environments,telemanipulation of robots have gained immense importance. One of the primary tasks in telemanipulating robots remotely, is the effective manipulation of the slave robot using the master manipulator. Ideally a kinematic replica of the slave manipulator is used as the master to provide a joint-to-joint control to the slave. This research uses the 7-DOF Whole Arm Manipulator© (WAM) as the master manipulator and a 6-DOF Titan as the slave manipulator. Due to the kinematic dissimilarity between the two, a Cartesian space position mapping technique is adapted in which the slave is made to follow the same trajectory as the end effector of the master with respect to its reference frame. The main criterion in undertaking this mapping approach is to provide a convenient region of operation to the human operator. Various methods like pseudo inverse, Jacobian transpose and Damped least squares have been used to perform the inverse kinematics for the Titan. Joint limit avoidance and obstacle avoidance constraints were used to perform the inverse kinematics for the WAM and thereby remove the redundancy. Finally a joint volume limitation constraint (JVLC) was adopted which aims at providing the operator, a comfortable operational space in union with the master manipulator. Each inverse methodfor the Titan was experimentally tested and the best method identified from thesimulation results and the error analysis. Various experiments were also performed for the constrained inverse kinematics for the WAM and results were simulated. RoboWorks© was used for simulation purposes